GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools

Problem, Formatting or Query -  Send Feedback

Was this page helpful?-10+1


rfc:rfc7970

Internet Engineering Task Force (IETF) R. Danyliw Request for Comments: 7970 CERT Obsoletes: 5070, 6685 November 2016 Category: Standards Track ISSN: 2070-1721

     The Incident Object Description Exchange Format Version 2

Abstract

 The Incident Object Description Exchange Format (IODEF) defines a
 data representation for security incident reports and indicators
 commonly exchanged by operational security teams for mitigation and
 watch and warning.  This document describes an updated information
 model for the IODEF and provides an associated data model specified
 with the XML schema.  This new information and data model obsoletes
 RFCs 5070 and 6685.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7970.

Danyliw Standards Track [Page 1] RFC 7970 IODEF Version 2 November 2016

Copyright Notice

 Copyright (c) 2016 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Danyliw Standards Track [Page 2] RFC 7970 IODEF Version 2 November 2016

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   5
   1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   6
   1.2.  Notations . . . . . . . . . . . . . . . . . . . . . . . .   6
   1.3.  About the IODEF Data Model  . . . . . . . . . . . . . . .   7
   1.4.  Changes from RFC 5070 . . . . . . . . . . . . . . . . . .   7
 2.  IODEF Data Types  . . . . . . . . . . . . . . . . . . . . . .   9
   2.1.  Integers  . . . . . . . . . . . . . . . . . . . . . . . .   9
   2.2.  Real Numbers  . . . . . . . . . . . . . . . . . . . . . .   9
   2.3.  Characters and Strings  . . . . . . . . . . . . . . . . .   9
   2.4.  Multilingual Strings  . . . . . . . . . . . . . . . . . .   9
   2.5.  Binary Strings  . . . . . . . . . . . . . . . . . . . . .  10
     2.5.1.  Base64 Bytes  . . . . . . . . . . . . . . . . . . . .  10
     2.5.2.  Hexadecimal Bytes . . . . . . . . . . . . . . . . . .  11
   2.6.  Enumerated Types  . . . . . . . . . . . . . . . . . . . .  11
   2.7.  Date-Time String  . . . . . . . . . . . . . . . . . . . .  11
   2.8.  Timezone String . . . . . . . . . . . . . . . . . . . . .  11
   2.9.  Port Lists  . . . . . . . . . . . . . . . . . . . . . . .  11
   2.10. Postal Address  . . . . . . . . . . . . . . . . . . . . .  12
   2.11. Telephone Number  . . . . . . . . . . . . . . . . . . . .  12
   2.12. Email String  . . . . . . . . . . . . . . . . . . . . . .  12
   2.13. Uniform Resource Locator Strings  . . . . . . . . . . . .  12
   2.14. Identifiers and Identifier References . . . . . . . . . .  12
   2.15. Software  . . . . . . . . . . . . . . . . . . . . . . . .  13
     2.15.1.  SoftwareReference Class  . . . . . . . . . . . . . .  14
   2.16. Extension . . . . . . . . . . . . . . . . . . . . . . . .  15
 3.  The IODEF Information Model . . . . . . . . . . . . . . . . .  18
   3.1.  IODEF-Document Class  . . . . . . . . . . . . . . . . . .  18
   3.2.  Incident Class  . . . . . . . . . . . . . . . . . . . . .  20
   3.3.  Common Attributes . . . . . . . . . . . . . . . . . . . .  23
     3.3.1.  restriction Attribute . . . . . . . . . . . . . . . .  23
     3.3.2.  observable-id Attribute . . . . . . . . . . . . . . .  25
   3.4.  IncidentID Class  . . . . . . . . . . . . . . . . . . . .  25
   3.5.  AlternativeID Class . . . . . . . . . . . . . . . . . . .  26
   3.6.  RelatedActivity Class . . . . . . . . . . . . . . . . . .  27
   3.7.  ThreatActor Class . . . . . . . . . . . . . . . . . . . .  28
   3.8.  Campaign Class  . . . . . . . . . . . . . . . . . . . . .  29
   3.9.  Contact Class . . . . . . . . . . . . . . . . . . . . . .  30
     3.9.1.  RegistryHandle Class  . . . . . . . . . . . . . . . .  34
     3.9.2.  PostalAddress Class . . . . . . . . . . . . . . . . .  35
     3.9.3.  Email Class . . . . . . . . . . . . . . . . . . . . .  36
     3.9.4.  Telephone Class . . . . . . . . . . . . . . . . . . .  37
   3.10. Discovery Class . . . . . . . . . . . . . . . . . . . . .  38
     3.10.1.  DetectionPattern Class . . . . . . . . . . . . . . .  40
   3.11. Method Class  . . . . . . . . . . . . . . . . . . . . . .  41
     3.11.1.  Reference Class  . . . . . . . . . . . . . . . . . .  42

Danyliw Standards Track [Page 3] RFC 7970 IODEF Version 2 November 2016

   3.12. Assessment Class  . . . . . . . . . . . . . . . . . . . .  43
     3.12.1.  SystemImpact Class . . . . . . . . . . . . . . . . .  45
     3.12.2.  BusinessImpact Class . . . . . . . . . . . . . . . .  48
     3.12.3.  TimeImpact Class . . . . . . . . . . . . . . . . . .  50
     3.12.4.  MonetaryImpact Class . . . . . . . . . . . . . . . .  52
     3.12.5.  Confidence Class . . . . . . . . . . . . . . . . . .  53
   3.13. History Class . . . . . . . . . . . . . . . . . . . . . .  54
     3.13.1.  HistoryItem Class  . . . . . . . . . . . . . . . . .  54
   3.14. EventData Class . . . . . . . . . . . . . . . . . . . . .  57
     3.14.1.  Relating the Incident and EventData Classes  . . . .  59
     3.14.2.  Recursive Definition of EventData  . . . . . . . . .  59
   3.15. Expectation Class . . . . . . . . . . . . . . . . . . . .  60
   3.16. Flow Class  . . . . . . . . . . . . . . . . . . . . . . .  63
   3.17. System Class  . . . . . . . . . . . . . . . . . . . . . .  64
   3.18. Node Class  . . . . . . . . . . . . . . . . . . . . . . .  67
     3.18.1.  Address Class  . . . . . . . . . . . . . . . . . . .  68
     3.18.2.  NodeRole Class . . . . . . . . . . . . . . . . . . .  69
     3.18.3.  Counter Class  . . . . . . . . . . . . . . . . . . .  73
   3.19. DomainData Class  . . . . . . . . . . . . . . . . . . . .  75
     3.19.1.  Nameservers Class  . . . . . . . . . . . . . . . . .  77
     3.19.2.  DomainContacts Class . . . . . . . . . . . . . . . .  78
   3.20. Service Class . . . . . . . . . . . . . . . . . . . . . .  79
     3.20.1.  ServiceName Class  . . . . . . . . . . . . . . . . .  80
     3.20.2.  ApplicationHeader Class  . . . . . . . . . . . . . .  81
   3.21. EmailData Class . . . . . . . . . . . . . . . . . . . . .  82
   3.22. Record Class  . . . . . . . . . . . . . . . . . . . . . .  83
     3.22.1.  RecordData Class . . . . . . . . . . . . . . . . . .  84
     3.22.2.  RecordPattern Class  . . . . . . . . . . . . . . . .  85
   3.23. WindowsRegistryKeysModified Class . . . . . . . . . . . .  87
     3.23.1.  Key Class  . . . . . . . . . . . . . . . . . . . . .  88
   3.24. CertificateData Class . . . . . . . . . . . . . . . . . .  89
     3.24.1.  Certificate Class  . . . . . . . . . . . . . . . . .  90
   3.25. FileData Class  . . . . . . . . . . . . . . . . . . . . .  90
     3.25.1.  File Class . . . . . . . . . . . . . . . . . . . . .  91
   3.26. HashData Class  . . . . . . . . . . . . . . . . . . . . .  92
     3.26.1.  Hash Class . . . . . . . . . . . . . . . . . . . . .  94
     3.26.2.  FuzzyHash Class  . . . . . . . . . . . . . . . . . .  95
   3.27. SignatureData Class . . . . . . . . . . . . . . . . . . .  95
   3.28. IndicatorData Class . . . . . . . . . . . . . . . . . . .  96
   3.29. Indicator Class . . . . . . . . . . . . . . . . . . . . .  96
     3.29.1.  IndicatorID Class  . . . . . . . . . . . . . . . . .  99
     3.29.2.  AlternativeIndicatorID Class . . . . . . . . . . . . 100
     3.29.3.  Observable Class . . . . . . . . . . . . . . . . . . 101
     3.29.4.  IndicatorExpression Class  . . . . . . . . . . . . . 106
     3.29.5.  Expressions with IndicatorExpression . . . . . . . . 108
     3.29.6.  ObservableReference Class  . . . . . . . . . . . . . 110
     3.29.7.  IndicatorReference Class . . . . . . . . . . . . . . 110
     3.29.8.  AttackPhase Class  . . . . . . . . . . . . . . . . . 111

Danyliw Standards Track [Page 4] RFC 7970 IODEF Version 2 November 2016

 4.  Processing Considerations . . . . . . . . . . . . . . . . . . 112
   4.1.  Encoding  . . . . . . . . . . . . . . . . . . . . . . . . 112
   4.2.  IODEF Namespace . . . . . . . . . . . . . . . . . . . . . 112
   4.3.  Validation  . . . . . . . . . . . . . . . . . . . . . . . 112
   4.4.  Incompatibilities with v1 . . . . . . . . . . . . . . . . 113
 5.  Extending the IODEF . . . . . . . . . . . . . . . . . . . . . 114
   5.1.  Extending the Enumerated Values of Attributes . . . . . . 114
     5.1.1.  Private Extension of Enumerated Values  . . . . . . . 114
     5.1.2.  Public Extension of Enumerated Values . . . . . . . . 115
   5.2.  Extending Classes . . . . . . . . . . . . . . . . . . . . 115
   5.3.  Deconflicting Private Extensions  . . . . . . . . . . . . 117
 6.  Internationalization Issues . . . . . . . . . . . . . . . . . 118
 7.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . . 119
   7.1.  Minimal Example . . . . . . . . . . . . . . . . . . . . . 119
   7.2.  Indicators from a Campaign  . . . . . . . . . . . . . . . 120
 8.  The IODEF Data Model (XML Schema) . . . . . . . . . . . . . . 121
 9.  Security Considerations . . . . . . . . . . . . . . . . . . . 161
   9.1.  Security  . . . . . . . . . . . . . . . . . . . . . . . . 161
   9.2.  Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 162
 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 163
   10.1.  Namespace and Schema . . . . . . . . . . . . . . . . . . 163
   10.2.  Enumerated Value Registries  . . . . . . . . . . . . . . 163
   10.3.  Expert Review of IODEF-Related XML Registry Entries  . . 166
 11. References  . . . . . . . . . . . . . . . . . . . . . . . . . 167
   11.1.  Normative References . . . . . . . . . . . . . . . . . . 167
   11.2.  Informative References . . . . . . . . . . . . . . . . . 170
 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 171
 Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . 172

1. Introduction

 Organizations require help from other parties to mitigate malicious
 activity targeting their network and to gain insight into potential
 threats.  This coordination might entail working with an ISP to
 filter attack traffic, contacting a remote site to take down a
 botnet, or sharing watch lists of known malicious indicators in a
 consortium.
 The Incident Object Description Exchange Format (IODEF) is a format
 for representing computer security information commonly exchanged
 between Computer Security Incident Response Teams (CSIRTs) or other
 operational security teams.  It provides an XML representation for
 conveying:
 o  indicators to characterize a threat;
 o  security incident reports to document attacks against an
    organization;

Danyliw Standards Track [Page 5] RFC 7970 IODEF Version 2 November 2016

 o  response activity taken or that could be taken in response to an
    incident; and
 o  metadata so that these various classes of information can be
    exchanged among parties.
 The purpose of the IODEF is to enhance the operational capabilities
 of CSIRTs.  Adoption of the IODEF will improve the ability of a CSIRT
 to resolve security incidents; understand threats; and coordinate
 response activities and proactive mitigations by simplifying
 collaboration and data sharing with its partners.  This structured
 format provided by the IODEF allows for:
 o  machine-to-machine exchange of incident and indicator data;
 o  automated processing of this data whereby allowing more rapid
    execution of appropriate courses of action; and
 o  the development of an ecosystem of interoperable tools enabling
    security operations.
 Sharing and coordinating with other organizations is not strictly a
 technical problem.  There are numerous procedural, cultural, legal,
 and trust-related barriers to overcome.  The IODEF does not attempt
 to address them directly.  However, operational implementations of
 the IODEF will need to consider these challenges.
 Section 1 provides the background for the IODEF.  Sections 3 and 8
 specify the IODEF information and data model, respectively.  The data
 types used in this document are described in Section 2.  Processing
 considerations, extending the specification, internationalization,
 and security issues are covered in Sections 4, 5, 6, and 9,
 respectively.  Examples are listed in Section 7.

1.1. Terminology

 The key words "MUST," "MUST NOT," "REQUIRED," "SHALL," "SHALL NOT,"
 "SHOULD," "SHOULD NOT," "RECOMMENDED," "MAY," and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].

1.2. Notations

 The IODEF is specified as an Extensible Markup Language (XML)
 [W3C.XML] schema [W3C.SCHEMA].  The normative IODEF data model is
 found in the XML schema in Section 8.  To aid in the understanding of
 the data elements, Section 3 also depicts the underlying information
 model using Unified Modeling Language (UML).  This abstract
 presentation of the IODEF is not normative.

Danyliw Standards Track [Page 6] RFC 7970 IODEF Version 2 November 2016

 For clarity in this document, the term "XML document" will be used
 when referring generically to any instance of an XML document.  The
 term "IODEF document" will be used to refer to an XML document
 conforming to the IODEF specification.  The terms "schema" will be
 used to refer to Section 8 of this document.  The terms "data model"
 and "schema" will be used interchangeably.  The terms "class" and
 "element" will be used to reference either the corresponding data
 element in the UML-based information or XML schema-based data models,
 respectively.

1.3. About the IODEF Data Model

 A number of considerations were made in the design of the IODEF data
 model.
 o  The data model found in this document is an evolution of the one
    previously specified in [RFC5070].  New fields were added to
    represent additional information.  [RFC5070] was developed
    primarily to represent incident reports.  This document builds
    upon it by adding support for indicators and revising it to
    reflect the current challenges faced by CSIRTs.  An attempt was
    made to preserve backward compatibility, but this was not possible
    in all cases.  See Section 4.4.  This document obsoletes
    [RFC5070].
 o  The IODEF is a transport format.  Therefore, the data model may
    not be the optimal archival or in-memory processing format.
 o  The IODEF is intended to be a framework to convey only commonly
    exchanged information.  It ensures that there are mechanisms for
    extensibility to support organization-specific information and
    techniques to reference information kept outside of the data
    model.
 o  Not all commonly exchanged information has a well-defined format
    or taxonomy.  The IODEF attempts to strike a balance between
    enforcing sufficient structure to allow automated processing and
    supporting free-form content that enables maximum flexibility.
 o  The IODEF fits into a broader ecosystem of standards and
    conventions.  An attempt was made to harmonize the data model with
    this context.

1.4. Changes from RFC 5070

 A detailed list of additions made to the data model in [RFC5070] are
 enumerated in this section.  See Section 4.4 for a list of
 incompatible changes.

Danyliw Standards Track [Page 7] RFC 7970 IODEF Version 2 November 2016

 o  Updated the data types (Section 2) to improve
    internationalization, clarify ambiguity, and ensure consistency in
    extensions.
 o  Added the observable-id attribute (Section 3.3.2) and
    IndicatorData class (Section 3.28) to represent indicators.
 o  Added the private-enum-name and private-enum-id attributes to the
    IODEF-Document class (Section 3.1) to disambiguate private
    extensions.
 o  Updated the Incident class (Section 3.2) to represent additional
    timing and workflow information.
 o  Added the ThreatActor (Section 3.7) and Campaign (Section 3.8)
    classes to represent attack attribution information.
 o  Updated the Contact class (Section 3.9) and its children to
    improve internationalization and represent additional information
    about an entity.
 o  Updated the Method class (Section 3.11) to improve extensibility
    through externally referenced resources.
 o  Added the Discovery class (Section 3.10) to describe how an
    incident was discovered.
 o  Updated the Assessment class (Section 3.12) to enable more
    descriptive characterizations of the impact of an incident.
 o  Updated the HistoryItem (Section 3.13.1) and Expectation
    (Section 3.15) classes to support a reference to a course of
    action.
 o  Updated the EventData class (Section 3.14) with additional
    metadata added to the Incident class.
 o  Updated the System class (Section 3.17) with additional metadata.
 o  Updated the Counter class (Section 3.18.3) to support additional
    rate metrics.
 o  Added DomainData (Section 3.19), EmailData (Section 3.21),
    WindowsRegistryKeysModified (Section 3.23), CertificateData
    (Section 3.24), and FileData (Section 3.25) classes to improve the
    description of an incident and support this data as indicators.

Danyliw Standards Track [Page 8] RFC 7970 IODEF Version 2 November 2016

 o  Added the SignatureData (Section 3.27) and HashData (Section 3.26)
    classes to represent digital signatures and hashes.
 o  Added support for public enumerated attribute extensions using
    IANA registries (Section 5.1.2).
 o  Updated numerous enumerated attributes for completeness.

2. IODEF Data Types

 The IODEF uses a number of simple and complex types.  This section
 describes these data types.

2.1. Integers

 An integer is represented in the information model by the INTEGER
 data type.  Integer data MUST be encoded in Base 10.
 The INTEGER data type is implemented in the data model as an
 "xs:integer" type per Section 3.3.13 of [W3C.SCHEMA.DTYPES].

2.2. Real Numbers

 A real (floating-point) number is represented in the information
 model by the REAL data type.  Real data MUST be encoded in Base 10.
 The REAL data type is implemented in the data model as an "xs:float"
 type per Section 3.2.4 of [W3C.SCHEMA.DTYPES].

2.3. Characters and Strings

 A single character is represented in the information model by the
 CHARACTER data type.  A string is represented by the STRING data
 type.  Special characters MUST be encoded using entity references.
 See Section 4.1.
 The CHARACTER and STRING data types are implemented in the data model
 as an "xs:string" type per Section 3.2.1 of [W3C.SCHEMA.DTYPES].

2.4. Multilingual Strings

 A string that needs to be represented in a human-readable language
 different than the default encoding of the document is represented in
 the information model by the ML_STRING data type.
 The ML_STRING data type is implemented in the data model as the
 "iodef:MLStringType" type.  This type extends the "xs:string" to
 include two attributes.

Danyliw Standards Track [Page 9] RFC 7970 IODEF Version 2 November 2016

 +------------------------+
 | iodef:MLStringType     |
 +------------------------+
 | xs:string              |
 |                        |
 | ENUM xml:lang          |
 | STRING translation-id  |
 +------------------------+
                 Figure 1: The iodef:MLStringType Type
 The content of the class is a character string of type "xs:string"
 whose language MAY be specified by the xml:lang attribute.
 The attributes of the iodef:MLStringType type are:
 xml:lang
    Optional.  ENUM.  A language identifier per Section 2.12 of
    [W3C.XML] whose values and format are described in [RFC5646].  The
    interpretation of this code is described in Section 6.
 translation-id
    Optional.  STRING.  An identifier to relate other instances of
    this class with the same parent as translations of this text.  The
    scope of this identifier is limited to all of the direct, peer
    child classes of a given parent class.
 Using this class enables representing translations of the same text
 in multiple languages.  Each translation is a distinct instance of
 this class with a common parent.  A group of classes each with a
 translated instance of text is related by setting a common identifier
 in the translation-id attribute.  The language of a given class is
 set by the xml:lang attribute.  See Section 6 for more details on
 representing translations of free-form text.

2.5. Binary Strings

 Binary octets can be represented with two encodings.

2.5.1. Base64 Bytes

 A binary octet encoded with base64 is represented in the information
 model by the BYTE data type.  A sequence of these octets is of the
 BYTE[] data type.
 The BYTE and BYTE[] data types are implemented in the data model as
 an "xs:base64Binary" type per Section 3.2.16 of [W3C.SCHEMA.DTYPES].

Danyliw Standards Track [Page 10] RFC 7970 IODEF Version 2 November 2016

2.5.2. Hexadecimal Bytes

 A binary octet encoded as a character tuple consistent of two
 hexadecimal digits is represented in the information model by the
 HEXBIN data type.  A sequence of these octets is of the HEXBIN[] data
 type.
 The HEXBIN and HEXBIN[] data types are implemented in the data model
 as an "xs:hexBinary" type per Section 3.2.15 of [W3C.SCHEMA.DTYPES].

2.6. Enumerated Types

 An enumerated type is represented in the information model by the
 ENUM data type.  It is an ordered list of acceptable string values.
 Each value has a representative keyword.  Within the data model, the
 enumerated type keywords are used as attribute values.
 The ENUM data type is implemented in the data model as values of an
 "xs:NMTOKEN" type per Section 3.3.4 of [W3C.SCHEMA.DTYPES].

2.7. Date-Time String

 A date-time string that describes a particular instant in time is
 represented in the information model by the DATETIME data type.
 Ranges are not supported.
 The DATETIME data type is implemented in the data model as an
 "xs:dateTime" type per Section 3.2.7 of [W3C.SCHEMA.DTYPES].

2.8. Timezone String

 A timezone offset from UTC is represented in the information model by
 the TIMEZONE data type.  It is formatted according to the following
 regular expression: "Z|[\+\-](0[0-9]|1[0-4]):[0-5][0-9]".
 The TIMEZONE data type is implemented in the data model as an
 "iodef:TimezoneType" type.

2.9. Port Lists

 A list of network ports is represented in the information model by
 the PORTLIST data type.  A PORTLIST consists of a comma-separated
 list of numbers and ranges (N-M means ports N through M, inclusive).
 It is formatted according to the following regular expression:
 "\d+(\-\d+)?(,\d+(\-\d+)?)*".  For example,
 "2,5-15,30,32,40-50,55-60".

Danyliw Standards Track [Page 11] RFC 7970 IODEF Version 2 November 2016

 The PORTLIST data type is implemented in the data model as an
 "iodef:PortlistType" type.

2.10. Postal Address

 A postal address is represented in the information model by the
 POSTAL data type.  The format of the POSTAL data type is documented
 in Section 2.23 of [RFC4519] as a free-form multi-line string
 separated by the "$" character.
 The POSTAL data type is implemented in the data model as an
 "iodef:MLStringType" type.

2.11. Telephone Number

 A telephone number is represented in the information model by the
 PHONE data type.  The format of the PHONE data type is documented in
 [E.164].
 The PHONE data type is implemented in the data model as an
 "xs:string" type per Section 3.2.1 of [W3C.SCHEMA.DTYPES].

2.12. Email String

 An email address is represented in the information model by the EMAIL
 data type.  The format of the EMAIL data type is documented in
 Section 3.4.1 of [RFC5322] and Section 3.3 of [RFC6531].
 The EMAIL data type is implemented in the data model as an
 "xs:string" type per Section 3.2.1 of [W3C.SCHEMA.DTYPES].

2.13. Uniform Resource Locator Strings

 A uniform resource locator (URL) is represented in the information
 model by the URL data type.  The format of the URL data type is
 documented in [RFC3986].
 The URL data type is implemented as an "xs:anyURI" type per
 Section 3.2.17 of [W3C.SCHEMA.DTYPES].

2.14. Identifiers and Identifier References

 An identifier unique to the IODEF document is represented in the
 information model by the ID data type.  A reference to this
 identifier is represented by the IDREF data type.

Danyliw Standards Track [Page 12] RFC 7970 IODEF Version 2 November 2016

 The ID and IDREF data types are implemented in the model as "xs:ID"
 and "xs:IDREF" types per Sections 3.3.8 and 3.3.9 of
 [W3C.SCHEMA.DTYPES].

2.15. Software

 A particular version of software is represented in the information
 model by the SOFTWARE data type.  This software can be described by
 using a reference, a URL, or with free-form text.
 The SOFTWARE data type is implemented in the data model as the
 "iodef:SoftwareType" type.
 +--------------------+
 | iodef:SoftwareType |
 +--------------------+
 |                    |<>--{0..1}--[ SoftwareReference ]
 |                    |<>--{0..*}--[ URL               ]
 |                    |<>--{0..*}--[ Description       ]
 +--------------------+
                    Figure 2: The SoftwareType Type
 The aggregate classes of the SoftwareType type are:
 SoftwareReference
    Zero or one.  Reference to a software application.  See
    Section 2.15.1.
 URL
    Zero or more.  URL.  A URL to a resource describing the software.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    software.
 At least one of these classes MUST be present.
 The iodef:SoftwareType type has no attributes.

Danyliw Standards Track [Page 13] RFC 7970 IODEF Version 2 November 2016

2.15.1. SoftwareReference Class

 The SoftwareReference class is a reference to a particular version of
 software.
 +----------------------+
 | SoftwareReference    |
 +----------------------+
 | xs:any               |
 |                      |
 | ENUM spec-name       |
 | STRING ext-spec-name |
 | ENUM dtype           |
 | STRING ext-dtype     |
 +----------------------+
                 Figure 3: The SoftwareReference Class
 The element content varies according to the value of the spec-name
 attribute.  It is defined in the data model as "xs:any" per
 [W3C.SCHEMA].
 The attributes of the SoftwareReference class are:
 spec-name
    Required.  ENUM.  Identifies the format and semantics of the
    element body of this class.  Formal standards and specifications
    can be referenced as well as a free-form text description with a
    user-provided data type.  These values are maintained in the
    "SoftwareReference-spec-id" IANA registry per Section 10.2
    1.  custom.  The element content is free-form and of the data type
        specified by the dtype attribute.  If this value is selected,
        then the dtype attribute MUST be set.
    2.  cpe.  The element content describes a Common Platform
        Enumeration (CPE) entry per [NIST.CPE].
    3.  swid.  The element content describes a software identification
        (SWID) tag per [ISO19770].
    4.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 14] RFC 7970 IODEF Version 2 November 2016

 ext-spec-name
    Optional.  STRING.  A means by which to extend the spec-name
    attribute.  See Section 5.1.1.
 dtype
    Optional.  ENUM.  The data type of the element content.  The
    permitted values for this attribute are shown below.  The default
    value is "string".  These values are maintained in the
    "SoftwareReference-dtype" IANA registry per Section 10.2.
    1.  bytes.  The element content is of type HEXBIN.
    2.  integer.  The element content is of type INTEGER.
    3.  real.  The element content is of type REAL.
    4.  string.  The element content is of type STRING.
    5.  xml.  The element content is XML.  See Section 5.2.
    6.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-dtype
    Optional.  STRING.  A means by which to extend the dtype
    attribute.  See Section 5.1.1.

2.16. Extension

 Information not otherwise represented in the IODEF can be added using
 the EXTENSION data type.  This data type is a generic extension
 mechanism.
 The EXTENSION data type is implemented in the data model as the
 "iodef:ExtensionType" type.
 The data type of an EXTENSION is described by the dtype attribute.
 For simple information, atomic data types (e.g., integers, strings)
 are supported.  Their semantics are further described by the meaning
 and formatid attributes.  Encapsulating XML documents conforming to
 another schema is also supported.  A detailed discussion of extending
 the schema can be found in Section 5.  Additional coordination may be
 required to ensure that a recipient of a document using this type can
 parse and process it.

Danyliw Standards Track [Page 15] RFC 7970 IODEF Version 2 November 2016

 +------------------------+
 | iodef:ExtensionType    |
 +------------------------+
 | xs:any                 |
 |                        |
 | STRING name            |
 | ENUM dtype             |
 | STRING ext-dtype       |
 | STRING meaning         |
 | STRING formatid        |
 | ENUM restriction       |
 | STRING ext-restriction |
 | ID observable-id       |
 +------------------------+
                Figure 4: The iodef:ExtensionType Type
 The element content of this type is the extension being added to the
 data model.  This content is defined in the data model as "xs:any"
 per [W3C.SCHEMA].
 The attributes of the iodef:ExtensionType type are:
 name
    Optional.  STRING.  A free-form name of the field or data element.
 dtype
    Required.  ENUM.  The data type of the element content.  The
    default value is "string".  These values are maintained in the
    "ExtensionType-dtype" IANA registry per Section 10.2.
    1.   boolean.  The element content is of type BOOLEAN.
    2.   byte.  The element content is of type BYTE.
    3.   bytes.  The element content is of type HEXBIN.
    4.   character.  The element content is of type CHARACTER.
    5.   date-time.  The element content is of type DATETIME.
    6.   ntpstamp.  Same as date-time.
    7.   integer.  The element content is of type INTEGER.
    8.   portlist.  The element content is of type PORTLIST.
    9.   real.  The element content is of type REAL.

Danyliw Standards Track [Page 16] RFC 7970 IODEF Version 2 November 2016

    10.  string.  The element content is of type STRING.
    11.  file.  The element content is a base64-encoded binary file
         encoded as a BYTE[] type.
    12.  path.  The element content is a file-system path encoded as a
         STRING type.
    13.  frame.  The element content is a Layer 2 frame encoded as a
         HEXBIN type.
    14.  packet.  The element content is a Layer 3 packet encoded as a
         HEXBIN type.
    15.  ipv4-packet.  The element content is an IPv4 packet encoded
         as a HEXBIN type.
    16.  ipv6-packet.  The element content is an IPv6 packet encoded
         as a HEXBIN type.
    17.  url.  The element content is of type URL.
    18.  csv.  The element content is a comma-separated value (CSV)
         list per Section 2 of [RFC4180] encoded as a STRING type.
    19.  winreg.  The element content is a Microsoft Windows registry
         key encoded as a STRING type.
    20.  xml.  The element content is XML.  See Section 5.2.
    21.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-dtype
    Optional.  STRING.  A means by which to extend the dtype
    attribute.  See Section 5.1.1.
 meaning
    Optional.  STRING.  A free-form text description of the element
    content.
 formatid
    Optional.  STRING.  An identifier referencing the format or
    semantics of the element content.

Danyliw Standards Track [Page 17] RFC 7970 IODEF Version 2 November 2016

 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3. The IODEF Information Model

 The specifics of the IODEF information model are discussed in this
 section.  Each class and its relationships with the other classes is
 described.  When necessary, clarifications are made about translating
 this information model to the schema in Section 8.

3.1. IODEF-Document Class

 The IODEF-Document class is the top level class in the IODEF data
 model.  All IODEF documents are an instance of this class.
 +--------------------------+
 | IODEF-Document           |
 +--------------------------+
 | STRING version           |<>--{1..*}--[ Incident       ]
 | ENUM xml:lang            |<>--{0..*}--[ AdditionalData ]
 | STRING format-id         |
 | STRING private-enum-name |
 | STRING private-enum-id   |
 +--------------------------+
                  Figure 5: The IODEF-Document Class
 The aggregate classes of the IODEF-Document class are:
 Incident
    One or more.  The information related to a single incident.  See
    Section 3.2.
 AdditionalData
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model.

Danyliw Standards Track [Page 18] RFC 7970 IODEF Version 2 November 2016

 The attributes of the IODEF-Document class are:
 version
    Required.  STRING.  The IODEF specification version number to
    which this IODEF document conforms.  The value of this attribute
    MUST be "2.00".
 xml:lang
    Optional.  ENUM.  A language identifier per Section 2.12 of
    [W3C.XML] whose values and form are described in [RFC5646].  The
    interpretation of this code is described in Section 6.
 format-id
    Optional.  STRING.  A free-form string to convey processing
    instructions to the recipient of the document.  Its semantics must
    be negotiated out of band.
 private-enum-name
    Optional.  STRING.  A globally unique identifier for the CSIRT
    generating the document to deconflict private extensions used in
    the document.  The fully qualified domain name (FQDN) associated
    with the CSIRT MUST be used as the identifier.  See Section 5.3.
 private-enum-id
    Optional.  STRING.  An organizationally unique identifier for an
    extension used in the document.  If this attribute is set, the
    private-enum-name MUST also be set.  See Section 5.3.

Danyliw Standards Track [Page 19] RFC 7970 IODEF Version 2 November 2016

3.2. Incident Class

 The Incident class describes commonly exchanged information when
 reporting or sharing derived analysis from security incidents.
 +-------------------------+
 | Incident                |
 +-------------------------+
 | ENUM purpose            |<>----------[ IncidentID      ]
 | STRING ext-purpose      |<>--{0..1}--[ AlternativeID   ]
 | ENUM status             |<>--{0..*}--[ RelatedActivity ]
 | STRING ext-status       |<>--{0..1}--[ DetectTime      ]
 | ENUM xml:lang           |<>--{0..1}--[ StartTime       ]
 | ENUM restriction        |<>--{0..1}--[ EndTime         ]
 | STRING ext-restriction  |<>--{0..1}--{ RecoveryTime    ]
 | ID observable-id        |<>--{0..1}--[ ReportTime      ]
 |                         |<>----------[ GenerationTime  ]
 |                         |<>--{0..*}--[ Description     ]
 |                         |<>--{0..*}  [ Discovery       ]
 |                         |<>--{0..*}--[ Assessment      ]
 |                         |<>--{0..*}--[ Method          ]
 |                         |<>--{1..*}--[ Contact         ]
 |                         |<>--{0..*}--[ EventData       ]
 |                         |<>--{0..1}--[ IndicatorData   ]
 |                         |<>--{0..1}--[ History         ]
 |                         |<>--{0..*}--[ AdditionalData  ]
 +-------------------------+
                     Figure 6: The Incident Class
 The aggregate classes of the Incident class are:
 IncidentID
    One.  An incident tracking number assigned to this incident by the
    CSIRT that generated the IODEF document.  See Section 3.4.
 AlternativeID
    Zero or one.  The incident tracking numbers used by other CSIRTs
    to refer to the incident described in the document.  See
    Section 3.5.
 RelatedActivity
    Zero or more.  Related activity and attribution of this activity.
    See Section 3.6.
 DetectTime
    Zero or one.  DATETIME.  The time the incident was first detected.

Danyliw Standards Track [Page 20] RFC 7970 IODEF Version 2 November 2016

 StartTime
    Zero or one.  DATETIME.  The time the incident started.
 EndTime
    Zero or one.  DATETIME.  The time the incident ended.
 RecoveryTime
    Zero or one.  DATETIME.  The time the site recovered from the
    incident.
 ReportTime
    Zero or one.  DATETIME.  The time the incident was reported.
 GenerationTime
    One.  DATETIME.  The time the content in this Incident class was
    generated.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    incident.
 Discovery
    Zero or more.  The means by which this incident was detected.  See
    Section 3.10.
 Assessment
    Zero or more.  A characterization of the impact of the incident.
    See Section 3.12.
 Method
    Zero or more.  The techniques used by the threat actor in the
    incident.  See Section 3.11.
 Contact
    One or more.  Contact information for the parties involved in the
    incident.  See Section 3.9.
 EventData
    Zero or more.  Description of the events comprising the incident.
    See Section 3.14.
 IndicatorData
    Zero or one.  Indicators from the analysis of an incident.  See
    Section 3.28.
 History
    Zero or one.  A log of significant events or actions that occurred
    during the course of handling the incident.  See Section 3.13.

Danyliw Standards Track [Page 21] RFC 7970 IODEF Version 2 November 2016

 AdditionalData
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model.
 The attributes of the Incident class are:
 purpose
    Required.  ENUM.  The purpose attribute describes the rationale
    for documenting the information in this class.  It is closely
    related to the Expectation class (Section 3.15).  These values are
    maintained in the "Incident-purpose" IANA registry per
    Section 10.2.  This attribute is defined as an enumerated list:
    1.  traceback.  The incident was sent for trace-back purposes.
    2.  mitigation.  The incident was sent to request aid in
        mitigating the described activity.
    3.  reporting.  The incident was sent to comply with reporting
        requirements.
    4.  watch.  The incident was sent to convey indicators that should
        be monitored.
    5.  other.  The incident was sent for purposes specified in the
        Expectation class.
    6.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-purpose
    Optional.  STRING.  A means by which to extend the purpose
    attribute.  See Section 5.1.1.
 status
    Optional.  ENUM.  The status attribute conveys the state in a
    workflow where the incident is currently found.  These values are
    maintained in the "Incident-status" IANA registry per
    Section 10.2.  This attribute is defined as an enumerated list:
    1.  new.  The incident is newly reported, and no action has been
        taken.
    2.  in-progress.  The incident is under investigation.
    3.  forwarded.  The incident has been forwarded to another party
        for handling.

Danyliw Standards Track [Page 22] RFC 7970 IODEF Version 2 November 2016

    4.  resolved.  The investigation into the activity in this
        incident has concluded.
    5.  future.  The described activity has not yet been detected.
    6.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-status
    Optional.  STRING.  A means by which to extend the status
    attribute.  See Section 5.1.1.
 xml:lang
    Optional.  ENUM.  A language identifier per Section 2.12 of
    [W3C.XML] whose values and form are described in [RFC5646].  The
    interpretation of this code is described in Section 6.
 restriction
    Optional.  ENUM.  See Section 3.3.1.  The default value is
    "private".
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.3. Common Attributes

 There are a number of recurring attributes used in the information
 model.  They are documented in this section.

3.3.1. restriction Attribute

 The restriction attribute indicates the disclosure guidelines to
 which the sender expects the recipient to adhere for the information
 represented in this class and its children.  This guideline provides
 no security since there are no technical means to ensure that the
 recipient of the document handles the information as the sender
 requested.
 The value of this attribute is logically inherited by the children of
 this class.  That is to say, the disclosure rules applied to this
 class also apply to its children.

Danyliw Standards Track [Page 23] RFC 7970 IODEF Version 2 November 2016

 It is possible to set a granular disclosure policy, since all of the
 high-level classes (i.e., children of the Incident class) have a
 restriction attribute.  Therefore, a child can override the
 guidelines of a parent class, be it to restrict or relax the
 disclosure rules (e.g., a child has a weaker policy than an ancestor;
 or an ancestor has a weak policy, and the children selectively apply
 more rigid controls).  The implicit value of the restriction
 attribute for a class that did not specify one can be found in the
 closest ancestor that did specify a value.
 This attribute is defined as an enumerated value with a default value
 of "private".  Note that the default value of the restriction
 attribute is only defined in the context of the Incident class.  In
 other classes where this attribute is used, no default is specified.
 These values are maintained in the "Restriction" IANA registry per
 Section 10.2.
 1.   public.  The information can be freely distributed without
      restriction.
 2.   partner.  The information may be shared within a closed
      community of peers, partners, or affected parties, but cannot be
      openly published.
 3.   need-to-know.  The information may be shared only within the
      organization with individuals that have a need to know.
 4.   private.  The information may not be shared.
 5.   default.  The information can be shared according to an
      information disclosure policy pre-arranged by the communicating
      parties.
 6.   white.  Same as 'public'.
 7.   green.  Same as 'partner'.
 8.   amber.  Same as 'need-to-know'.
 9.   red.  Same as 'private'.
 10.  ext-value.  A value used to indicate that this attribute is
      extended and the actual value is provided using the
      corresponding ext-* attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 24] RFC 7970 IODEF Version 2 November 2016

3.3.2. observable-id Attribute

 The observable-id attribute tags information in the document as an
 observable so that it can be referenced later in the description of
 an indicator.  The value of this attribute is a unique identifier in
 the scope of the document.  It is used by the ObservableReference
 class to enumerate observables when defining an indicator with the
 IndicatorData class.

3.4. IncidentID Class

 The IncidentID class represents a tracking number that is unique in
 the context of the CSIRT.  It serves as an identifier for an incident
 or a document identifier when sharing indicators.  This identifier
 would serve as an index into a CSIRT's incident handling or knowledge
 management system.
 The combination of the name attribute and the string in the element
 content MUST be a globally unique identifier describing the activity.
 Documents generated by a given CSIRT MUST NOT reuse the same value
 unless they are referencing the same incident.
 +------------------------+
 | IncidentID             |
 +------------------------+
 | STRING                 |
 |                        |
 | STRING name            |
 | STRING instance        |
 | ENUM restriction       |
 | STRING ext-restriction |
 +------------------------+
                    Figure 7: The IncidentID Class
 The content of the class is an incident identifier of type STRING.
 The attributes of the IncidentID class are:
 name
    Required.  STRING.  An identifier describing the CSIRT that
    created the document.  In order to have a globally unique CSIRT
    name, the fully qualified domain name associated with the CSIRT
    MUST be used.

Danyliw Standards Track [Page 25] RFC 7970 IODEF Version 2 November 2016

 instance
    Optional.  STRING.  An identifier referencing a subset of the
    named incident.
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.5. AlternativeID Class

 The AlternativeID class lists the tracking numbers used by CSIRTs,
 other than the one generating the document, to refer to the identical
 activity described in the IODEF document.  A tracking number listed
 as an AlternativeID references the same incident detected by another
 CSIRT.  The tracking numbers of the CSIRT that generated the IODEF
 document must never be considered an AlternativeID.
 +------------------------+
 | AlternativeID          |
 +------------------------+
 | ENUM restriction       |<>--{1..*}--[ IncidentID ]
 | STRING ext-restriction |
 +------------------------+
                   Figure 8: The AlternativeID Class
 The aggregate class of the AlternativeID class is:
 IncidentID
    One or more.  The tracking number of another CSIRT.  See
    Section 3.4.
 The attributes of the AlternativeID class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 26] RFC 7970 IODEF Version 2 November 2016

3.6. RelatedActivity Class

 The RelatedActivity class relates the information described in the
 rest of the document to previously observed incidents or activity and
 allows attribution to a specific actor or campaign.
 +------------------------+
 | RelatedActivity        |
 +------------------------+
 | ENUM restriction       |<>--{0..*}--[ IncidentID     ]
 | STRING ext-restriction |<>--{0..*}--[ URL            ]
 |                        |<>--{0..*}--[ ThreatActor    ]
 |                        |<>--{0..*}--[ Campaign       ]
 |                        |<>--{0..*}--[ IndicatorID    ]
 |                        |<>--{0..1}--[ Confidence     ]
 |                        |<>--{0..*}--[ Description    ]
 |                        |<>--{0..*}--[ AdditionalData ]
 +------------------------+
                  Figure 9: The RelatedActivity Class
 The aggregate classes of the RelatedActivity class are:
 IncidentID
    Zero or more.  The tracking number of a related incident.  See
    Section 3.4.
 URL
    Zero or more.  URL.  A URL to activity related to this incident.
 ThreatActor
    Zero or more.  The threat actor to whom the incident activity is
    attributed.  See Section 3.7.
 Campaign
    Zero or more.  The campaign of a given threat actor to whom the
    described activity is attributed.  See Section 3.8.
 IndicatorID
    Zero or more.  A reference to a related indicator.  See
    Section 3.4.
 Confidence
    Zero or one.  An estimate of the confidence in attributing this
    RelatedActivity to the events described in the document.  See
    Section 3.12.5.

Danyliw Standards Track [Page 27] RFC 7970 IODEF Version 2 November 2016

 Description
    Zero or more.  ML_STRING.  A description of how these
    relationships were derived.
 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.
 The RelatedActivity class MUST have at least one instance of any of
 the following child classes: IncidentID, URL, ThreatActor, Campaign,
 Description, or AdditionalData.
 The attributes of the RelatedActivity class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.7. ThreatActor Class

 The ThreatActor class describes a threat actor.
 +------------------------+
 | ThreatActor            |
 +------------------------+
 | ENUM restriction       |<>--{0..*}--[ ThreatActorID  ]
 | STRING ext-restriction |<>--{0..*}--[ URL            ]
 |                        |<>--{0..*}--[ Description    ]
 |                        |<>--{0..*}--[ AdditionalData ]
 +------------------------+
                   Figure 10: The ThreatActor Class
 The aggregate classes of the ThreatActor class are:
 ThreatActorID
    Zero or more.  STRING.  An identifier for the threat actor.
 URL
    Zero or more.  URL.  A URL to a reference describing the threat
    actor.
 Description
    Zero or more.  ML_STRING.  A description of the threat actor.

Danyliw Standards Track [Page 28] RFC 7970 IODEF Version 2 November 2016

 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.
 The ThreatActor class MUST have at least one instance of a child
 class.
 The attributes of the ThreatActor class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.8. Campaign Class

 The Campaign class describes a campaign of attacks by a threat actor.
 +------------------------+
 | Campaign               |
 +------------------------+
 | ENUM restriction       |<>--{0..*}--[ CampaignID     ]
 | STRING ext-restriction |<>--{0..*}--[ URL            ]
 |                        |<>--{0..*}--[ Description    ]
 |                        |<>--{0..*}--[ AdditionalData ]
 +------------------------+
                     Figure 11: The Campaign Class
 The aggregate classes of the Campaign class are:
 CampaignID
    Zero or more.  STRING.  An identifier for the campaign.
 URL
    Zero or more.  URL.  A URL to a reference describing the campaign.
 Description
    Zero or more.  ML_STRING.  A description of the campaign.
 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.
 The Campaign class MUST have at least one instance of a child class.

Danyliw Standards Track [Page 29] RFC 7970 IODEF Version 2 November 2016

 The attributes of the Campaign class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.9. Contact Class

 The Contact class describes contact information for organizations and
 personnel involved in the incident.  This class allows for the naming
 of the involved party, specifying contact information for them, and
 identifying their role in the incident.
 People and organizations are treated interchangeably as contacts; one
 can be associated with the other using the recursive definition of
 the class (the Contact class is aggregated into the Contact class).
 The type attribute disambiguates the type of contact information
 being provided.
 The recursive definition of Contact provides a way to relate
 information without requiring the explicit use of identifiers or
 duplication of data.  A complete point of contact is derived by a
 particular traversal from the root Contact class to the leaf Contact
 class.  Each child Contact class logically inherits contact
 information from its ancestors.
 +------------------------+
 | Contact                |
 +------------------------+
 | ENUM role              |<>--{0..*}--[ ContactName    ]
 | STRING ext-role        |<>--{0..*}--[ ContactTitle   ]
 | ENUM type              |<>--{0..*}--[ Description    ]
 | STRING ext-type        |<>--{0..*}--[ RegistryHandle ]
 | ENUM restriction       |<>--{0..*}--[ PostalAddress  ]
 | STRING ext-restriction |<>--{0..*}--[ Email          ]
 |                        |<>--{0..*}--[ Telephone      ]
 |                        |<>--{0..1}--[ Timezone       ]
 |                        |<>--{0..*}--[ Contact        ]
 |                        |<>--{0..*}--[ AdditionalData ]
 +------------------------+
                     Figure 12: The Contact Class

Danyliw Standards Track [Page 30] RFC 7970 IODEF Version 2 November 2016

 The aggregate classes of the Contact class are:
 ContactName
    Zero or more.  ML_STRING.  The name of the contact.  The contact
    may either be an organization or a person.  The type attribute
    disambiguates the semantics.
 ContactTitle
    Zero or more.  ML_STRING.  The title for the individual named in
    the ContactName.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    contact.
 RegistryHandle
    Zero or more.  A handle name into the registry of the contact.
    See Section 3.9.1.
 PostalAddress
    Zero or more.  The postal address of the contact.  See
    Section 3.9.2.
 Email
    Zero or more.  The email address of the contact.  See
    Section 3.9.3.
 Telephone
    Zero or more.  The telephone number of the contact.  See
    Section 3.9.4.
 Timezone
    Zero or one.  TIMEZONE.  The timezone in which the contact
    resides.
 Contact
    Zero or more.  A recursive definition of the Contact class.  This
    definition can be used to group common data pertaining to multiple
    points of contact and is especially useful when listing multiple
    contacts at the same organization.
 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.
 At least one of the aggregate classes MUST be present in an instance
 of the Contact class.

Danyliw Standards Track [Page 31] RFC 7970 IODEF Version 2 November 2016

 The attributes of the Contact class are:
 role
    Required.  ENUM.  Indicates the role the contact fulfills.  These
    values are maintained in the "Contact-role" IANA registry per
    Section 10.2.
    1.   creator.  The entity that generates the document.
    2.   reporter.  The entity that reported the information.
    3.   admin.  An administrative contact or business owner for an
         asset or organization.
    4.   tech.  An entity responsible for the day-to-day management of
         technical issues for an asset or organization.
    5.   provider.  An external hosting provider for an asset.
    6.   user.  An end-user of an asset or part of an organization.
    7.   billing.  An entity responsible for billing issues for an
         asset or organization.
    8.   legal.  An entity responsible for legal issues related to an
         asset or organization.
    9.   irt.  An entity responsible for handling security issues for
         an asset or organization.
    10.  abuse.  An entity responsible for handling abuse originating
         from an asset or organization.
    11.  cc.  An entity that is to be kept informed about the events
         related to an asset or organization.
    12.  cc-irt.  A CSIRT or information-sharing organization
         coordinating activity related to an asset or organization.
    13.  leo.  A law enforcement organization supporting the
         investigation of activity affecting an asset or organization.
    14.  vendor.  The vendor that produces an asset.
    15.  vendor-support.  A vendor that provides services.
    16.  victim.  A victim in the incident.

Danyliw Standards Track [Page 32] RFC 7970 IODEF Version 2 November 2016

    17.  victim-notified.  A victim in the incident who has been
         notified.
    18.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-role
    Optional.  STRING.  A means by which to extend the role attribute.
    See Section 5.1.1.
 type
    Required.  ENUM.  Indicates the type of contact being described.
    This attribute is defined as an enumerated list.  These values are
    maintained in the "Contact-type" IANA registry per Section 10.2.
    1.  person.  The information for this contact references an
        individual.
    2.  organization.  The information for this contact references an
        organization.
    3.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 33] RFC 7970 IODEF Version 2 November 2016

3.9.1. RegistryHandle Class

 The RegistryHandle class represents a handle into an Internet
 registry or community-specific database.
 +---------------------+
 | RegistryHandle      |
 +---------------------+
 | STRING              |
 |                     |
 | ENUM registry       |
 | STRING ext-registry |
 +---------------------+
                  Figure 13: The RegistryHandle Class
 The content of the class is a handle into a registry of type STRING.
 The attributes of the RegistryHandle class are:
 registry
    Required.  ENUM.  The database to which the handle belongs.  These
    values are maintained in the "RegistryHandle-registry" IANA
    registry per Section 10.2.  The possible values are:
    1.  internic.  Internet Network Information Center
    2.  apnic.  Asia Pacific Network Information Center
    3.  arin.  American Registry for Internet Numbers
    4.  lacnic.  Latin American and Caribbean Internet Addresses
        Registry
    5.  ripe.  Reseaux IP Europeens
    6.  afrinic.  African Network Information Center
    7.  local.  A database local to the CSIRT
    8.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-registry
    Optional.  STRING.  A means by which to extend the registry
    attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 34] RFC 7970 IODEF Version 2 November 2016

3.9.2. PostalAddress Class

 The PostalAddress class specifies a postal address and associated
 annotation.
 +--------------------+
 | PostalAddress      |
 +--------------------+
 | ENUM type          |<>----------[ PAddress         ]
 | STRING ext-type    |<>--{0..*}--[ Description      ]
 +--------------------+
                  Figure 14: The PostalAddress Class
 The aggregate classes of the PostalAddress class are:
 PAddress
    One.  POSTAL.  A postal address.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    address.
 The attributes of the PostalAddress class are:
 type
    Optional.  ENUM.  Categorizes the type of address described in the
    PAddress class.  These values are maintained in the
    "PostalAddress-type" IANA registry per Section 10.2.
    1.  street.  An address describing a physical location.
    2.  mailing.  An address to which correspondence should be sent.
    3.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.

Danyliw Standards Track [Page 35] RFC 7970 IODEF Version 2 November 2016

3.9.3. Email Class

 The Email class specifies an email address and associated annotation.
 +--------------------+
 | Email              |
 +--------------------+
 | ENUM type          |<>----------[ EmailTo          ]
 | STRING ext-type    |<>--{0..*}--[ Description      ]
 +--------------------+
                      Figure 15: The Email Class
 The aggregate classes of the Email class are:
 EmailTo
    One.  EMAIL.  An email address.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    email address.
 The attributes of the Email class are:
 type
    Optional.  ENUM.  Categorizes the type of email address described
    in the EmailTo class.  These values are maintained in the "Email-
    type" IANA registry per Section 10.2.
    1.  direct.  An email address of an individual.
    2.  hotline.  An email address regularly monitored for operational
        purposes.
    3.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.

Danyliw Standards Track [Page 36] RFC 7970 IODEF Version 2 November 2016

3.9.4. Telephone Class

 The Telephone class describes a telephone number and associated
 annotation.
 +--------------------+
 | Telephone          |
 +--------------------+
 | ENUM type          |<>----------[ TelephoneNumber  ]
 | STRING ext-type    |<>--{0..*}--[ Description      ]
 +--------------------+
                    Figure 16: The Telephone Class
 The aggregate classes of the Telephone class are:
 TelephoneNumber
    One.  PHONE.  A telephone number.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    phone number.
 The attributes of the Telephone class are:
 type
    Optional.  ENUM.  Categorizes the type of telephone number
    described in the TelephoneNumber class.  These values are
    maintained in the "Telephone-type" IANA registry per Section 10.2.
    1.  wired.  A number of a wire-line (land-line) phone.
    2.  mobile.  A number of a mobile phone.
    3.  fax.  A number to a fax machine.
    4.  hotline.  A number to a regularly monitored operational
        hotline.
    5.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.

Danyliw Standards Track [Page 37] RFC 7970 IODEF Version 2 November 2016

3.10. Discovery Class

 The Discovery class describes how an incident was detected.
 +------------------------+
 | Discovery              |
 +------------------------+
 | ENUM source            |<>--{0..*}--[ Description      ]
 | STRING ext-source      |<>--{0..*}--[ Contact          ]
 | ENUM restriction       |<>--{0..*}--[ DetectionPattern ]
 | STRING ext-restriction |
 +------------------------+
                    Figure 17: The Discovery Class
 The aggregate classes of the Discovery class are:
 Description
    Zero or more.  ML_STRING.  A free-form text description of how
    this incident was detected.
 Contact
    Zero or more.  Contact information for the party that discovered
    the incident.  See Section 3.9.
 DetectionPattern
    Zero or more.  Describes an application-specific configuration
    that detected the incident.  See Section 3.10.1.
 The attributes of the Discovery class are:
 source
    Optional.  ENUM.  Categorizes the techniques used to discover the
    incident.  These values are partially derived from Table 3-1 of
    [NIST800.61rev2].  These values are maintained in the "Discovery-
    source" IANA registry per Section 10.2.
    1.   nidps.  Network Intrusion Detection or Prevention System.
    2.   hips.  Host-based Intrusion Prevention System.
    3.   siem.  Security Information and Event Management System.
    4.   av.  Antivirus or antispam software.
    5.   third-party-monitoring.  Contracted third-party monitoring
         service.

Danyliw Standards Track [Page 38] RFC 7970 IODEF Version 2 November 2016

    6.   incident.  The activity was discovered while investigating an
         unrelated incident.
    7.   os-log.  Operating system logs.
    8.   application-log.  Application logs.
    9.   device-log.  Network device logs.
    10.  network-flow.  Network flow analysis.
    11.  passive-dns.  Passive DNS analysis.
    12.  investigation.  Manual investigation initiated based on
         notification of a new vulnerability or exploit.
    13.  audit.  Security audit.
    14.  internal-notification.  A party within the organization
         reported the activity.
    15.  external-notification.  A party outside of the organization
         reported the activity.
    16.  leo.  A law enforcement organization notified the victim
         organization.
    17.  partner.  A customer or business partner reported the
         activity to the victim organization.
    18.  actor.  The threat actor directly or indirectly reported this
         activity to the victim organization.
    19.  unknown.  Unknown detection approach.
    20.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-source
    Optional.  STRING.  A means by which to extend the source
    attribute.  See Section 5.1.1.
 restriction
    Optional.  ENUM.  See Section 3.3.1.

Danyliw Standards Track [Page 39] RFC 7970 IODEF Version 2 November 2016

 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.10.1. DetectionPattern Class

 The DetectionPattern class describes a configuration or signature
 that can be used by an Intrusion Detection System (IDS) / Intrusion
 Prevention System (IPS), SIEM, antivirus, endpoint protection,
 network analysis, malware analysis, or host forensics tool to
 identify a particular phenomenon.  This class requires the
 identification of the target application and allows the configuration
 to be described in either free form or machine-readable form.
 +------------------------+
 | DetectionPattern       |
 +------------------------+
 | ENUM restriction       |<>----------[ Application            ]
 | STRING ext-restriction |<>--{0..*}--[ Description            ]
 | ID observable-id       |<>--{0..*}--[ DetectionConfiguration ]
 +------------------------+
                 Figure 18: The DetectionPattern Class
 The aggregate classes of the DetectionPattern class are:
 Application
    One.  SOFTWARE.  The application for which the
    DetectionConfiguration or Description is being provided.
 Description
    Zero or more.  ML_STRING.  A free-form text description of how to
    use the information provided in the Application or
    DetectionConfiguration classes.
 DetectionConfiguration
    Zero or more.  STRING.  A machine-consumable configuration to find
    a pattern of activity.
 An instance of either the Description or DetectionConfiguration class
 MUST be present.
 The attributes of the DetectionPattern class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.

Danyliw Standards Track [Page 40] RFC 7970 IODEF Version 2 November 2016

 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.11. Method Class

 The Method class describes the tactics, techniques, procedures, or
 weakness used by the threat actor in an incident.  This class
 consists of both a list of references describing the attack methods
 and weaknesses and a free-form text description.
 +------------------------+
 | Method                 |
 +------------------------+
 | ENUM restriction       |<>--{0..*}--[ Reference         ]
 | STRING ext-restriction |<>--{0..*}--[ Description       ]
 |                        |<>--{0..*}--[ sci:AttackPattern ]
 |                        |<>--{0..*}--[ sci:Vulnerability ]
 |                        |<>--{0..*}--[ sci:Weakness      ]
 |                        |<>--{0..*}--[ AdditionalData    ]
 +------------------------+
                      Figure 19: The Method Class
 The aggregate classes of the Method class are:
 Reference
    Zero or more.  A reference to a vulnerability, malware sample,
    advisory, or analysis of an attack technique.  See Section 3.11.1.
 Description
    Zero or more.  ML_STRING.  A free-form text description of
    techniques, tactics, or procedures used by the threat actor.
 sci:AttackPattern
    Zero or more.  A reference to a pattern of attack or exploitation
    per [RFC7203].
 sci:Vulnerability
    Zero or more.  A reference to a vulnerability per [RFC7203].
 sci:Weakness
    Zero or more.  A reference to the exploited weakness per
    [RFC7203].

Danyliw Standards Track [Page 41] RFC 7970 IODEF Version 2 November 2016

 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.
 An instance of one of these children MUST be present.
 The attributes of the Method class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.11.1. Reference Class

 The Reference class is an external reference to relevant information
 such as a vulnerability, IDS alert, malware sample, advisory, or
 attack technique.
 +-------------------------+
 | Reference               |
 +-------------------------+
 | ID observable-id        |<>--{0..1}--[ enum:ReferenceName ]
 |                         |<>--{0..*}--[ URL                ]
 |                         |<>--{0..*}--[ Description        ]
 +-------------------------+
                    Figure 20: The Reference Class
 The aggregate classes of the Reference class are:
 enum:ReferenceName
    Zero or one.  Reference identifier per [RFC7495].
 URL
    Zero or more.  URL.  A URL to a reference.
 Description
    Zero or more.  ML_STRING.  A free-form text description of this
    reference.
 At least one of these classes MUST be present.

Danyliw Standards Track [Page 42] RFC 7970 IODEF Version 2 November 2016

 The attribute of the Reference class is:
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.12. Assessment Class

 The Assessment class describes the repercussions of the incident to
 the victim.
 +-------------------------+
 | Assessment              |
 +-------------------------+
 | ENUM occurrence         |<>--{0..*}--[ IncidentCategory ]
 | ENUM restriction        |<>--{0..*}--[ SystemImpact     ]
 | STRING ext-restriction  |<>--{0..*}--[ BusinessImpact   ]
 | ID observable-id        |<>--{0..*}--[ TimeImpact       ]
 |                         |<>--{0..*}--[ MonetaryImpact   ]
 |                         |<>--{0..*}--[ IntendedImpact   ]
 |                         |<>--{0..*}--[ Counter          ]
 |                         |<>--{0..*}--[ MitigatingFactor ]
 |                         |<>--{0..*}--[ Cause            ]
 |                         |<>--{0..1}--[ Confidence       ]
 |                         |<>--{0..*}--[ AdditionalData   ]
 +-------------------------+
                    Figure 21: The Assessment Class
 The aggregate classes of the Assessment class are:
 IncidentCategory
    Zero or more.  ML_STRING.  A free-form text description
    categorizing the type of incident.
 SystemImpact
    Zero or more.  A technical characterization of the impact of the
    incident activity on the victim's enterprise.  See Section 3.12.1.
 BusinessImpact
    Zero or more.  Impact of the incident activity on the business
    functions of the victim organization.  See Section 3.12.2.
 TimeImpact
    Zero or more.  A characterization of the victim organization due
    to the incident activity as a function of time.  See
    Section 3.12.3.

Danyliw Standards Track [Page 43] RFC 7970 IODEF Version 2 November 2016

 MonetaryImpact
    Zero or more.  The financial loss due to the incident activity.
    See Section 3.12.4.
 IntendedImpact
    Zero or more.  The intended outcome to the victim sought by the
    threat actor.  Defined identically to the BusinessImpact defined
    in Section 3.12.2 but describes intent rather than the realized
    impact.
 Counter
    Zero or more.  A counter with which to summarize the magnitude of
    the activity.  See Section 3.18.3.
 MitigatingFactor
    Zero or more.  ML_STRING.  A description of a mitigating factor
    relative to the impact on the victim organization.
 Cause
    Zero or more.  ML_STRING.  A description of an underlying cause of
    the impact.
 Confidence
    Zero or one.  An estimate of confidence in the impact assessment.
    See Section 3.12.5.
 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.
 At least one instance of the possible five impact classes (i.e.,
 SystemImpact, BusinessImpact, TimeImpact, MonetaryImpact, or
 IntendedImpact) MUST be present.
 The attributes of the Assessment class are:
 occurrence
    Optional.  ENUM.  Specifies whether the assessment is describing
    actual or potential outcomes.
    1.  actual.  This assessment describes activity that has occurred.
    2.  potential.  This assessment describes potential activity that
        might occur.
 restriction
    Optional.  ENUM.  See Section 3.3.1.

Danyliw Standards Track [Page 44] RFC 7970 IODEF Version 2 November 2016

 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.12.1. SystemImpact Class

 The SystemImpact class describes the technical impact of the incident
 to the systems on the network.
 +-----------------------+
 | SystemImpact          |
 +-----------------------+
 | ENUM severity         |<>--{0..*}--[ Description ]
 | ENUM completion       |
 | ENUM type             |
 | STRING ext-type       |
 +-----------------------+
                   Figure 22: The SystemImpact Class
 The aggregate class of the SystemImpact class is:
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    impact to the system.
 The attributes of the SystemImpact class are:
 severity
    Optional.  ENUM.  An estimate of the relative severity of the
    activity.  The permitted values are shown below.  There is no
    default value.
    1.  low.  Low severity
    2.  medium.  Medium severity
    3.  high.  High severity

Danyliw Standards Track [Page 45] RFC 7970 IODEF Version 2 November 2016

 completion
    Optional.  ENUM.  An indication whether the described activity was
    successful.  The permitted values are shown below.  There is no
    default value.
    1.  failed.  The attempted activity was not successful.
    2.  succeeded.  The attempted activity succeeded.
 type
    Required.  ENUM.  Classifies the impact.  The permitted values are
    shown below.  The default value is "unknown".  These values are
    maintained in the "SystemImpact-type" IANA registry per
    Section 10.2.
    1.   takeover-account.  Control was taken of a given account.
    2.   takeover-service.  Control was taken of a given service.
    3.   takeover-system.  Control was taken of a given system.
    4.   cps-manipulation.  A cyber-physical system was manipulated.
    5.   cps-damage.  A cyber-physical system was damaged.
    6.   availability-data.  Access to particular data was degraded or
         denied.
    7.   availability-account.  Access to an account was degraded or
         denied.
    8.   availability-service.  Access to a service was degraded or
         denied.
    9.   availability-system.  Access to a system was degraded or
         denied.
    10.  damaged-system.  Hardware on a system was irreparably
         damaged.
    11.  damaged-data.  Data on a system was deleted.
    12.  breach-proprietary.  Sensitive or proprietary information was
         accessed or exfiltrated.
    13.  breach-privacy.  Personally identifiable information was
         accessed or exfiltrated.

Danyliw Standards Track [Page 46] RFC 7970 IODEF Version 2 November 2016

    14.  breach-credential.  Credential information was accessed or
         exfiltrated.
    15.  breach-configuration.  System configuration or data inventory
         was access or exfiltrated.
    16.  integrity-data.  Data on the system was modified.
    17.  integrity-configuration.  Application or system configuration
         was modified.
    18.  integrity-hardware.  Firmware of a hardware component was
         modified.
    19.  traffic-redirection.  Network traffic on the system was
         redirected
    20.  monitoring-traffic.  Network traffic emerging from a host or
         enclave was monitored.
    21.  monitoring-host.  System activity (e.g., running processes,
         keystrokes) were monitored.
    22.  policy.  Activity violated the system owner's acceptable use
         policy.
    23.  unknown.  The impact is unknown.
    24.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.

Danyliw Standards Track [Page 47] RFC 7970 IODEF Version 2 November 2016

3.12.2. BusinessImpact Class

 The BusinessImpact class describes and characterizes the degree to
 which the function of the organization was impacted by the incident.
 +-------------------------+
 | BusinessImpact          |
 +-------------------------+
 | ENUM severity           |<>--{0..*}--[ Description ]
 | STRING ext-severity     |
 | ENUM type               |
 | STRING ext-type         |
 +-------------------------+
                  Figure 23: The BusinessImpact Class
 The aggregate class of the BusinessImpact class is:
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    impact to the organization.
 The attributes of the BusinessImpact class are:
 severity
    Optional.  ENUM.  Characterizes the severity of the incident on
    business functions.  The permitted values are shown below.  They
    were derived from Table 3-2 of [NIST800.61rev2].  The default
    value is "unknown".  These values are maintained in the
    "BusinessImpact-severity" IANA registry per Section 10.2.
    1.  none.  No effect to the organization's ability to provide all
        services to all users.
    2.  low.  Minimal effect as the organization can still provide all
        critical services to all users but has lost efficiency.
    3.  medium.  The organization has lost the ability to provide a
        critical service to a subset of system users.
    4.  high.  The organization is no longer able to provide some
        critical services to any users.
    5.  unknown.  The impact is not known.
    6.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 48] RFC 7970 IODEF Version 2 November 2016

 ext-severity
    Optional.  STRING.  A means by which to extend the severity
    attribute.  See Section 5.1.1.
 type
    Required.  ENUM.  Characterizes the effect this incident had on
    the business.  The permitted values are shown below.  The default
    value is "unknown".  These values are maintained in the
    "BusinessImpact-type" IANA registry per Section 10.2.
    1.   breach-proprietary.  Sensitive or proprietary information was
         accessed or exfiltrated.
    2.   breach-privacy.  Personally identifiable information was
         accessed or exfiltrated.
    3.   breach-credential.  Credential information was accessed or
         exfiltrated.
    4.   loss-of-integrity.  Sensitive or proprietary information was
         changed or deleted.
    5.   loss-of-service.  Service delivery was disrupted.
    6.   theft-financial.  Money was stolen.
    7.   theft-service.  Services were misappropriated.
    8.   degraded-reputation.  The reputation of the organization's
         brand was diminished.
    9.   asset-damage.  A cyber-physical system was damaged.
    10.  asset-manipulation.  A cyber-physical system was manipulated.
    11.  legal.  The incident resulted in legal or regulatory action.
    12.  extortion.  The incident resulted in actors extorting the
         victim organization.
    13.  unknown.  The impact is unknown.
    14.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 49] RFC 7970 IODEF Version 2 November 2016

 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.

3.12.3. TimeImpact Class

 The TimeImpact class describes the impact of the incident on an
 organization as a function of time.  It provides a way to convey down
 time and recovery time.
 +---------------------+
 | TimeImpact          |
 +---------------------+
 | REAL                |
 |                     |
 | ENUM severity       |
 | ENUM metric         |
 | STRING ext-metric   |
 | ENUM duration       |
 | STRING ext-duration |
 +---------------------+
                    Figure 24: The TimeImpact Class
 The content of the class is of type REAL and specifies an amount of
 time.  The duration attribute provides units for this content, and
 the metric attribute explains what this content is measuring.
 The attributes of the TimeImpact class are:
 severity
    Optional.  ENUM.  An estimate of the relative severity of the
    activity.  The permitted values are shown below.  There is no
    default value.
    1.  low.  Low severity
    2.  medium.  Medium severity
    3.  high.  High severity
 metric
    Required.  ENUM.  Defines the meaning of the value in the element
    content.  These values are maintained in the "TimeImpact-metric"
    IANA registry per Section 10.2.
    1.  labor.  Total staff time to recovery from the activity (e.g.,
        2 employees working 4 hours each would be 8 hours).

Danyliw Standards Track [Page 50] RFC 7970 IODEF Version 2 November 2016

    2.  elapsed.  Elapsed time from the beginning of the recovery to
        its completion (i.e., wall-clock time).
    3.  downtime.  Duration of time for which some provided service(s)
        was not available.
    4.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-metric
    Optional.  STRING.  A means by which to extend the metric
    attribute.  See Section 5.1.1.
 duration
    Optional.  ENUM.  Defines the unit of time for the value in the
    element content.  The default value is "hour".  These values are
    maintained in the "TimeImpact-duration" IANA registry per
    Section 10.2.
    1.  second.  The unit of the element content is seconds.
    2.  minute.  The unit of the element content is minutes.
    3.  hour.  The unit of the element content is hours.
    4.  day.  The unit of the element content is days.
    5.  month.  The unit of the element content is months.
    6.  quarter.  The unit of the element content is quarters.
    7.  year.  The unit of the element content is years.
    8.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-duration
    Optional.  STRING.  A means by which to extend the duration
    attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 51] RFC 7970 IODEF Version 2 November 2016

3.12.4. MonetaryImpact Class

 The MonetaryImpact class describes the financial impact of the
 activity on an organization.  For example, this impact may consider
 losses due to the cost of the investigation or recovery, diminished
 productivity of the staff, or a tarnished reputation that will affect
 future opportunities.
 +------------------+
 | MonetaryImpact   |
 +------------------+
 | REAL             |
 |                  |
 | ENUM severity    |
 | STRING currency  |
 +------------------+
                  Figure 25: The MonetaryImpact Class
 The content of the class is of type REAL and specifies a quantity of
 money.  The currency attribute defines the currency of this value.
 The attributes of the MonetaryImpact class are:
 severity
    Optional.  ENUM.  An estimate of the relative severity of the
    activity.  The permitted values are shown below.  There is no
    default value.
    1.  low.  Low severity
    2.  medium.  Medium severity
    3.  high.  High severity
 currency
    Optional.  STRING.  Defines the currency in which the value in the
    element content is expressed.  The permitted values are defined in
    "Codes for the representation of currencies" [ISO4217].  There is
    no default value.

Danyliw Standards Track [Page 52] RFC 7970 IODEF Version 2 November 2016

3.12.5. Confidence Class

 The Confidence class represents an estimate of the validity and
 accuracy of data expressed in the document.  This estimate can be
 expressed as a category or a numeric calculation.
 +-------------------+
 | Confidence        |
 +-------------------+
 | REAL              |
 |                   |
 | ENUM rating       |
 | STRING ext-rating |
 +-------------------+
                    Figure 26: The Confidence Class
 The content of the class is of type REAL and specifies a numerical
 assessment in the confidence of the data when the value of the rating
 attribute is "numeric".  Otherwise, this element MUST be empty.
 The attributes of the Confidence class are:
 rating
    Required.  ENUM.  A qualitative assessment of confidence.  These
    values are maintained in the "Confidence-rating" IANA registry per
    Section 10.2
    1.  low.  Low confidence.
    2.  medium.  Medium confidence.
    3.  high.  High confidence.
    4.  numeric.  The element content contains a number that conveys
        the confidence of the data.  The semantics of this number is
        outside the scope of this specification.
    5.  unknown.  The confidence rating value is not known.
    6.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-rating
    Optional.  STRING.  A means by which to extend the rating
    attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 53] RFC 7970 IODEF Version 2 November 2016

3.13. History Class

 The History class is a log of the significant events or actions
 performed by the involved parties during the course of handling the
 incident.
 The level of detail maintained in this log is left up to the
 discretion of those handling the incident.
 +------------------------+
 | History                |
 +------------------------+
 | ENUM restriction       |<>--{1..*}--[ HistoryItem ]
 | STRING ext-restriction |
 +------------------------+
                     Figure 27: The History Class
 The aggregate classes of the History class are:
 HistoryItem
    One or more.  An entry in the history log of significant events or
    actions performed by the involved parties.  See Section 3.13.1.
 The attributes of the History class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.13.1. HistoryItem Class

 The HistoryItem class is an entry in the History (Section 3.13) log
 that documents a particular action or event that occurred in the
 course of handling the incident.  The details of the entry are a
 free-form text description, but each can be categorized with the type
 attribute.

Danyliw Standards Track [Page 54] RFC 7970 IODEF Version 2 November 2016

 +-------------------------+
 | HistoryItem             |
 +-------------------------+
 | ENUM action             |<>----------[ DateTime       ]
 | STRING ext-action       |<>--{0..1}--[ IncidentID     ]
 | ENUM restriction        |<>--{0..1}--[ Contact        ]
 | STRING ext-restriction  |<>--{0..*}--[ Description    ]
 | ID observable-id        |<>--{0..*}--[ DefinedCOA     ]
 |                         |<>--{0..*}--[ AdditionalData ]
 +-------------------------+
                   Figure 28: The HistoryItem Class
 The aggregate classes of the HistoryItem class are:
 DateTime
    One.  DATETIME.  A timestamp of this entry in the history log.
 IncidentID
    Zero or one.  In a history log created by multiple parties, the
    IncidentID provides a mechanism to specify which CSIRT created a
    particular entry and references this organization's tracking
    number.  When a single organization is maintaining the log, this
    class can be ignored.  See Section 3.4.
 Contact
    Zero or one.  Provides contact information for the entity that
    performed the action documented in this class.  See Section 3.9.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    action or event.
 DefinedCOA
    Zero or more.  STRING.  An identifier meaningful to the sender and
    recipient of this document that references a course of action
    (COA).  This class MUST be present if the action attribute is set
    to "defined-coa".
 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.

Danyliw Standards Track [Page 55] RFC 7970 IODEF Version 2 November 2016

 The attributes of the HistoryItem class are:
 action
    Required.  ENUM.  Classifies a performed action or occurrence
    documented in this history log entry.  As activity will likely
    have been instigated either through a previously conveyed
    expectation or through an internal investigation, this attribute
    is identical to the action attribute of the Expectation class.
    The difference is only one of tense.  When an action is in this
    class, it has been completed.  See Section 3.15.
 ext-action
    Optional.  STRING.  A means by which to extend the action
    attribute.  See Section 5.1.1.
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

Danyliw Standards Track [Page 56] RFC 7970 IODEF Version 2 November 2016

3.14. EventData Class

 The EventData class is a container class to organize data about
 events that occurred during an incident.
 +-------------------------+
 | EventData               |
 +-------------------------+
 | ENUM restriction        |<>--{0..*}--[ Description    ]
 | STRING ext-restriction  |<>--{0..1}--[ DetectTime     ]
 | ID observable-id        |<>--{0..1}--[ StartTime      ]
 |                         |<>--{0..1}--[ EndTime        ]
 |                         |<>--{0..1}--[ RecoveryTime   ]
 |                         |<>--{0..1}--[ ReportTime     ]
 |                         |<>--{0..*}--[ Contact        ]
 |                         |<>--{0..*}--[ Discovery      ]
 |                         |<>--{0..1}--[ Assessment     ]
 |                         |<>--{0..*}--[ Method         ]
 |                         |<>--{0..*}--[ Flow           ]
 |                         |<>--{0..*}--[ Expectation    ]
 |                         |<>--{0..1}--[ Record         ]
 |                         |<>--{0..*}--[ EventData      ]
 |                         |<>--{0..*}--[ AdditionalData ]
 +-------------------------+
                    Figure 29: The EventData Class
 The aggregate classes of the EventData class are:
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    event.
 DetectTime
    Zero or one.  DATETIME.  The time the event was detected.
 StartTime
    Zero or one.  DATETIME.  The time the event started.
 EndTime
    Zero or one.  DATETIME.  The time the event ended.
 RecoveryTime
    Zero or one.  DATETIME.  The time the site recovered from the
    event.
 ReportTime
    Zero or one.  DATETIME.  The time the event was reported.

Danyliw Standards Track [Page 57] RFC 7970 IODEF Version 2 November 2016

 Contact
    Zero or more.  Contact information for the parties involved in the
    event.  See Section 3.9.
 Discovery
    Zero or more.  The means by which the event was detected.  See
    Section 3.10.
 Assessment
    Zero or one.  The impact of the event on the victim and the
    actions taken.  See Section 3.12.
 Method
    Zero or more.  The technique used by the threat actor in the
    event.  See Section 3.11.
 Flow
    Zero or more.  A description of the systems or networks involved.
    See Section 3.16.
 Expectation
    Zero or more.  The expected action to be performed by the
    recipient for the described event.  See Section 3.15.
 Record
    Zero or one.  Supportive data (e.g., log files) that provides
    additional information about the event.  See Section 3.22.
 EventData
    Zero or more.  A recursive definition of the EventData class.  See
    Section 3.14.2 for an explanation on using this class.
 AdditionalData
    Zero or more.  EXTENSION.  An extension mechanism for data not
    explicitly represented in the data model.
 At least one of the aggregate classes MUST be present in an instance
 of the EventData class.
 The attributes of the EventData class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.  The default value is
    "default".
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 58] RFC 7970 IODEF Version 2 November 2016

 observable-id
    Optional.  ID.  See Section 3.3.2.

3.14.1. Relating the Incident and EventData Classes

 There is substantial overlap in the child classes aggregated in the
 Incident and EventData classes.  Nevertheless, the semantics of these
 classes are quite different.  The Incident class provides summary
 information about the entire incident, while the EventData class
 provides information about the individual events comprising the
 incident.  In the common case, the EventData class will provide more
 specific information for the general description provided in the
 Incident class.  However, in the case where the summarized
 information in the Incident class conflicts with the detailed
 information in an EventData class, the more specific EventData class
 MUST supersede the more generic information provided in the Incident
 class.

3.14.2. Recursive Definition of EventData

 The EventData class is a container for the properties of an event in
 an incident.  These properties include: the hosts involved, impact of
 the incident activity on the hosts, forensic logs, etc.  The
 recursive definition of EventData allows for the grouping of related
 information with common properties.  This approach eliminates the
 need for explicit identifiers to relate information or duplicate it.
 Instead, the relative depth (nesting) of a class is used to group
 (relate) information.
 For example, consider a case where two hosts experience different
 impacts during an incident.  However, these two hosts have common
 contact information.  A depiction of how this situation would be
 represented can be found in Figure 30.  EventData (2) and (3) group
 each of the two hosts with their unique impact.  EventData (1)
 describes the common Contact class these two hosts share.

Danyliw Standards Track [Page 59] RFC 7970 IODEF Version 2 November 2016

 +------------------+
 | EventData (1)    |
 +------------------+
 |                  |<>----[ Contact    ]
 |                  |
 |                  |<>----[ EventData (2) ]<>----[ Flow       ]
 |                  |      [               ]<>----[ Assessment ]
 |                  |
 |                  |<>----[ EventData (3) ]<>----[ Flow       ]
 |                  |      [               ]<>----[ Assessment ]
 +------------------+
              Figure 30: Recursion in the EventData Class

3.15. Expectation Class

 The Expectation class conveys to the recipient of the IODEF document
 the actions the sender is requesting.
 +-------------------------+
 | Expectation             |
 +-------------------------+
 | ENUM action             |<>--{0..*}--[ Description ]
 | STRING ext-action       |<>--{0..*}--[ DefinedCOA  ]
 | ENUM severity           |<>--{0..1}--[ StartTime   ]
 | ENUM restriction        |<>--{0..1}--[ EndTime     ]
 | STRING ext-restriction  |<>--{0..1}--[ Contact     ]
 | ID observable-id        |
 +-------------------------+
                   Figure 31: The Expectation Class
 The aggregate classes of the Expectation class are:
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    desired action(s).
 DefinedCOA
    Zero or more.  STRING.  A unique identifier meaningful to the
    sender and recipient of this document that references a course of
    action.  This class MUST be present if the action attribute is set
    to "defined-coa".

Danyliw Standards Track [Page 60] RFC 7970 IODEF Version 2 November 2016

 StartTime
    Zero or one.  DATETIME.  The time at which the sender would like
    the action performed.  A timestamp that is earlier than the
    ReportTime specified in the Incident class denotes that the sender
    would like the action performed as soon as possible.  The absence
    of this element indicates no expectations of when the recipient
    would like the action performed.
 EndTime
    Zero or one.  DATETIME.  The time by which the sender expects the
    recipient to complete the action.  If the recipient cannot
    complete the action before EndTime, the recipient MUST NOT carry
    out the action.  Because of transit delays and clock drift, the
    sender MUST be prepared for the recipient to have carried out the
    action, even if it completes past EndTime.
 Contact
    Zero or one.  The entity expected to perform the action.  See
    Section 3.9.
 The attributes of the Expectation class are:
 action
    Optional.  ENUM.  Classifies the type of action requested.  The
    default value of "other".  These values are maintained in the
    "Expectation-action" IANA registry per Section 10.2.
    1.   nothing.  No action is requested.  Do nothing with the
         information.
    2.   contact-source-site.  Contact the site(s) identified as the
         source of the activity.
    3.   contact-target-site.  Contact the site(s) identified as the
         target of the activity.
    4.   contact-sender.  Contact the originator of the document.
    5.   investigate.  Investigate the system(s) listed in the event.
    6.   block-host.  Block traffic from the machine(s) listed as
         sources in the event.
    7.   block-network.  Block traffic from the network(s) lists as
         sources in the event.
    8.   block-port.  Block the port listed as sources in the event.

Danyliw Standards Track [Page 61] RFC 7970 IODEF Version 2 November 2016

    9.   rate-limit-host.  Rate-limit the traffic from the machine(s)
         listed as sources in the event.
    10.  rate-limit-network.  Rate-limit the traffic from the
         network(s) lists as sources in the event.
    11.  rate-limit-port.  Rate-limit the port(s) listed as sources in
         the event.
    12.  redirect-traffic.  Redirect traffic from the intended
         recipient for further analysis.
    13.  honeypot.  Redirect traffic from systems listed in the event
         to a honeypot for further analysis.
    14.  upgrade-software.  Upgrade or patch the software or firmware
         on an asset listed in the event.
    15.  rebuild-asset.  Reinstall the operating system or
         applications on an asset listed in the event.
    16.  harden-asset.  Change the configuration of an asset listed in
         the event to reduce the attack surface.
    17.  remediate-other.  Remediate the activity in a way other than
         by rate-limiting or blocking.
    18.  status-triage.  Confirm receipt and begin triaging the
         incident.
    19.  status-new-info.  Notify the sender when new information is
         received for this incident.
    20.  watch-and-report.  Watch for the described activity or
         indicators, and notify the sender when seen.
    21.  training.  Train user to identify or mitigate the described
         threat.
    22.  defined-coa.  Perform a predefined course of action (COA).
         The COA is named in the DefinedCOA class.
    23.  other.  Perform a custom action described in the Description
         class.
    24.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 62] RFC 7970 IODEF Version 2 November 2016

 ext-action
    Optional.  STRING.  A means by which to extend the action
    attribute.  See Section 5.1.1.
 severity
    Optional.  ENUM.  Indicates the desired priority of the action.
    This attribute is an enumerated list with no default value, and
    the semantics of these relative measures are context dependent.
    1.  low.  Low priority
    2.  medium.  Medium priority
    3.  high.  High priority
 restriction
    Optional.  ENUM.  See Section 3.3.1.  The default value is
    "default".
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.16. Flow Class

 The Flow class describes the systems and networks involved in the
 incident and the relationships between them.
 +------------------+
 | Flow             |
 +------------------+
 |                  |<>--{1..*}--[ System   ]
 +------------------+
                       Figure 32: The Flow Class
 The aggregate class of the Flow class is:
 System
    One or More.  A host or network involved in an event.  See
    Section 3.17.
 The Flow class has no attributes.

Danyliw Standards Track [Page 63] RFC 7970 IODEF Version 2 November 2016

3.17. System Class

 The System class describes a system or network involved in an event.
 +------------------------+
 | System                 |
 +------------------------+
 | ENUM category          |<>----------[ Node            ]
 | STRING ext-category    |<>--{0..*}--[ NodeRole        ]
 | STRING interface       |<>--{0..*}--[ Service         ]
 | ENUM spoofed           |<>--{0..*}--[ OperatingSystem ]
 | ENUM virtual           |<>--{0..*}--[ Counter         ]
 | ENUM ownership         |<>--{0..*}--[ AssetID         ]
 | STRING ext-ownership   |<>--{0..*}--[ Description     ]
 | ENUM restriction       |<>--{0..*}--[ AdditionalData  ]
 | STRING ext-restriction |
 | ID observable-id       |
 +------------------------+
                      Figure 33: The System Class
 The aggregate classes of the System class are:
 Node
    One.  A host or network involved in the incident.  See
    Section 3.18.
 NodeRole
    Zero or more.  The intended purpose of the system.  See
    Section 3.18.2.
 Service
    Zero or more.  A network service running on the system.  See
    Section 3.20.
 OperatingSystem
    Zero or more.  SOFTWARE.  The operating system running on the
    system.
 Counter
    Zero or more.  A counter with which to summarize properties of
    this host or network.  See Section 3.18.3.
 AssetID
    Zero or more.  STRING.  An asset identifier for the System.

Danyliw Standards Track [Page 64] RFC 7970 IODEF Version 2 November 2016

 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    System.
 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.
 The attributes of the System class are:
 category
    Optional.  ENUM.  Classifies the role the host or network played
    in the incident.  These values are maintained in the "System-
    category" IANA registry per Section 10.2.
    1.  source.  The System was the source of the event.
    2.  target.  The System was the target of the event.
    3.  intermediate.  The System was an intermediary in the event.
    4.  sensor.  The System was a sensor monitoring the event.
    5.  infrastructure.  The System was an infrastructure node of the
        IODEF document exchange.
    6.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-category
    Optional.  STRING.  A means by which to extend the category
    attribute.  See Section 5.1.1.
 interface
    Optional.  STRING.  Specifies the interface on which the event(s)
    on this System originated.  If the Node class specifies a network
    rather than a host, this attribute has no meaning.
 spoofed
    Optional.  ENUM.  An indication of confidence in whether this
    System was the true target or attacking host.  The permitted
    values for this attribute are shown below.  The default value is
    "unknown".
    1.  unknown.  The accuracy of the category attribute value is
        unknown.

Danyliw Standards Track [Page 65] RFC 7970 IODEF Version 2 November 2016

    2.  yes.  The category attribute value is likely incorrect.  In
        the case of a source, the System is likely a decoy; with a
        target, the System was likely not the intended victim.
    3.  no.  The category attribute value is believed to be correct.
 virtual
    Optional.  ENUM.  Indicates whether this System is a virtual or
    physical device.  The default value is "unknown".
    1.  yes.  The System is a virtual device.
    2.  no.  The System is a physical device.
    3.  unknown.  It is not known if the System is virtual.
 ownership
    Optional.  ENUM.  Describes the ownership of this System relative
    to the victim in the incident.  These values are maintained in the
    "System-ownership" IANA registry per Section 10.2.
    1.  organization.  Corporate or enterprise owned.
    2.  personal.  Personally owned by an employee or affiliate of the
        corporation or enterprise.
    3.  partner.  Owned by a partner of the corporation or enterprise.
    4.  customer.  Owned by a customer of the corporation or
        enterprise.
    5.  no-relationship.  Owned by an entity that has no known
        relationship with the victim organization.
    6.  unknown.  Ownership is unknown.
    7.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-ownership
    Optional.  STRING.  A means by which to extend the ownership
    attribute.  See Section 5.1.1.
 restriction
    Optional.  ENUM.  See Section 3.3.1.

Danyliw Standards Track [Page 66] RFC 7970 IODEF Version 2 November 2016

 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.18. Node Class

 The Node class identifies a system, asset, or network and its
 location.
 +---------------+
 | Node          |
 +---------------+
 |               |<>--{0..*}--[ DomainData    ]
 |               |<>--{0..*}--[ Address       ]
 |               |<>--{0..1}--[ PostalAddress ]
 |               |<>--{0..*}--[ Location      ]
 |               |<>--{0..*}--[ Counter       ]
 +---------------+
                       Figure 34: The Node Class
 The aggregate classes of the Node class are:
 DomainData
    Zero or more.  The domain (DNS) information associated with this
    node.  If an Address is not provided, at least one DomainData MUST
    be specified.  See Section 3.19.
 Address
    Zero or more.  The hardware, network, or application address of
    the node.  If a DomainData is not provided, at least one Address
    MUST be specified.  See Section 3.18.1.
 PostalAddress
    Zero or one.  POSTAL.  The postal address of the node.
 Location
    Zero or more.  ML_STRING.  A free-form text description of the
    physical location of the node.  This description may provide a
    more detailed description of where at the address specified by the
    PostalAddress class this node is found (e.g., room number, rack
    number, or slot number in a chassis).

Danyliw Standards Track [Page 67] RFC 7970 IODEF Version 2 November 2016

 Counter
    Zero or more.  A counter with which to summarize properties of
    this host or network.  See Section 3.18.3.
 The Node class has no attributes.

3.18.1. Address Class

 The Address class represents a hardware (Layer 2), network (Layer 3),
 or application (Layer 7) address.
 +-------------------------+
 | Address                 |
 +-------------------------+
 | STRING                  |
 |                         |
 | ENUM category           |
 | STRING ext-category     |
 | STRING vlan-name        |
 | INTEGER vlan-num        |
 | ID observable-id        |
 +-------------------------+
                     Figure 35: The Address Class
 The content of the class is an address of type STRING whose semantics
 are determined by the category attribute.
 The attributes of the Address class are:
 category
    Required.  ENUM.  The type of address represented.  The default
    value is "ipv6-addr".  These values are maintained in the
    "Address-category" IANA registry per Section 10.2.
    1.   asn.  Autonomous System Number.
    2.   atm.  Asynchronous Transfer Mode (ATM) address.
    3.   e-mail.  Email address, per the EMAIL data type.
    4.   ipv4-addr.  IPv4 host address in dotted-decimal notation
         (i.e., a.b.c.d).
    5.   ipv4-net.  IPv4 network address in dotted-decimal notation,
         slash, significant bits (i.e., a.b.c.d/nn).

Danyliw Standards Track [Page 68] RFC 7970 IODEF Version 2 November 2016

    6.   ipv4-net-masked.  A sanitized IPv4 address with significant
         bits per "ipv4-net" but with the character 'x' replacing any
         digit(s) in the address or prefix.
    7.   ipv4-net-mask.  IPv4 network address in dotted-decimal
         notation, slash, network mask in dotted-decimal notation
         (i.e., a.b.c.d/w.x.y.z).
    8.   ipv6-addr.  IPv6 host address per Section 4 of [RFC5952].
    9.   ipv6-net.  IPv6 network address, slash, prefix per
         Section 2.3 of [RFC4291].
    10.  ipv6-net-masked.  A sanitized IPv6 address and prefix per
         "ipv6-net" but with the character 'x' replacing any
         hexadecimal digit(s) in the address or digit(s) in the
         prefix.
    11.  mac.  Media Access Control (MAC) address (i.e.,
         aa:bb:cc:dd:ee:ff).
    12.  site-uri.  A URL or URI for a resource, per the URL data
         type.
    13.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-category
    Optional.  STRING.  A means by which to extend the category
    attribute.  See Section 5.1.1.
 vlan-name
    Optional.  STRING.  The name of the Virtual LAN to which the
    address belongs.
 vlan-num
    Optional.  INTEGER.  The number of the Virtual LAN to which the
    address belongs.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.18.2. NodeRole Class

 The NodeRole class describes the function performed by or role of a
 particular system, asset, or network.

Danyliw Standards Track [Page 69] RFC 7970 IODEF Version 2 November 2016

 +-----------------------+
 | NodeRole              |
 +-----------------------+
 | ENUM category         |<>--{0..*}--[ Description ]
 | STRING ext-category   |
 +-----------------------+
                     Figure 36: The NodeRole Class
 The aggregate class of the NodeRole class is:
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    role of the system.
 The attributes of the NodeRole class are:
 category
    Required.  ENUM.  Function or role of a node.  These values are
    maintained in the "NodeRole-category" IANA registry per
    Section 10.2.
    1.   client.  Client computer.
    2.   client-enterprise.  Client computer on the enterprise
         network.
    3.   client-partner.  Client computer on network of a partner.
    4.   client-remote.  Client computer remotely connected to the
         enterprise network.
    5.   client-kiosk.  Client computer serving as a kiosk.
    6.   client-mobile.  Mobile device.
    7.   server-internal.  Server with internal services.
    8.   server-public.  Server with public services.
    9.   www.  WWW server.
    10.  mail.  Mail server.
    11.  webmail.  Web mail server.
    12.  messaging.  Messaging server (e.g., NNTP, IRC, IM).

Danyliw Standards Track [Page 70] RFC 7970 IODEF Version 2 November 2016

    13.  streaming.  Streaming-media server.
    14.  voice.  Voice server (e.g., SIP, H.323).
    15.  file.  File server.
    16.  ftp.  FTP server.
    17.  p2p.  Peer-to-peer node.
    18.  name.  Name server (e.g., DNS, WINS).
    19.  directory.  Directory server (e.g., LDAP, finger, whois).
    20.  credential.  Credential server (e.g., domain controller,
         Kerberos).
    21.  print.  Print server.
    22.  application.  Application server.
    23.  database.  Database server.
    24.  backup.  Backup server.
    25.  dhcp.  DHCP server.
    26.  assessment.  Assessment server (e.g., vulnerability scanner,
         endpoint assessment).
    27.  source-control.  Source code control server.
    28.  config-management.  Configuration management server.
    29.  monitoring.  Security monitoring server (e.g., IDS).
    30.  infra.  Infrastructure server (e.g., router, firewall, DHCP).
    31.  infra-firewall.  Firewall.
    32.  infra-router.  Router.
    33.  infra-switch.  Switch.
    34.  camera.  Camera and video system.
    35.  proxy.  Proxy server.

Danyliw Standards Track [Page 71] RFC 7970 IODEF Version 2 November 2016

    36.  remote-access.  Remote access server.
    37.  log.  Log server (e.g., syslog).
    38.  virtualization.  Server running virtual machines.
    39.  pos.  Point-of-sale device.
    40.  scada.  Supervisory control and data acquisition (SCADA)
         system.
    41.  scada-supervisory.  Supervisory system for a SCADA.
    42.  sinkhole.  Traffic sinkhole destination.
    43.  honeypot.  Honeypot server.
    44.  anonymization.  Anonymization server (e.g., Tor node).
    45.  c2-server.  Malicious command and control server.
    46.  malware-distribution.  Server that distributes malware
    47.  drop-server.  Server to which exfiltrated content is
         uploaded.
    48.  hop-point.  Intermediary server used to get to a victim.
    49.  reflector.  A system used in a reflector attack.
    50.  phishing-site.  Site hosting phishing content.
    51.  spear-phishing-site.  Site hosting spear-phishing content.
    52.  recruiting-site.  Site to recruit.
    53.  fraudulent-site.  Fraudulent site.
    54.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-category
    Optional.  STRING.  A means by which to extend the category
    attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 72] RFC 7970 IODEF Version 2 November 2016

3.18.3. Counter Class

 The Counter class summarizes multiple occurrences of an event or
 conveys counts or rates of various features.
 The complete semantics of this class are context dependent based on
 the class in which it is aggregated.
 +---------------------+
 | Counter             |
 +---------------------+
 | REAL                |
 |                     |
 | ENUM type           |
 | STRING ext-type     |
 | ENUM unit           |
 | STRING ext-unit     |
 | STRING meaning      |
 | ENUM duration       |
 | STRING ext-duration |
 +---------------------+
                     Figure 37: The Counter Class
 The content of the class is a value of type REAL whose meaning and
 units are determined by the type and duration attributes,
 respectively.  If the duration attribute is present, the element
 content is a rate.  Otherwise, it is a simple counter.
 The attributes of the Counter class are:
 type
    Required.  ENUM.  Specifies the type of counter specified in the
    element content.  These values are maintained in the "Counter-
    type" IANA registry per Section 10.2.
    1.  count.  The Counter class value is a counter.
    2.  peak.  The Counter class value is a peak value.
    3.  average.  The Counter class value is an average.
    4.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 73] RFC 7970 IODEF Version 2 November 2016

 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.
 unit
    Required.  ENUM.  Specifies the units of the element content.
    These values are maintained in the "Counter-unit" IANA registry
    per Section 10.2.
    1.   byte.  Bytes transferred.
    2.   mbit.  Megabits (Mbits) transferred.
    3.   packet.  Packets.
    4.   flow.  Network flow records.
    5.   session.  Sessions.
    6.   alert.  Notifications generated by another system (e.g., IDS
         or SIEM system).
    7.   message.  Messages (e.g., mail messages).
    8.   event.  Events.
    9.   host.  Hosts.
    10.  site.  Site.
    11.  organization.  Organizations.
    12.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-unit
    Optional.  STRING.  A means by which to extend the unit attribute.
    See Section 5.1.1.
 meaning
    Optional.  STRING.  A free-form text description of the metric
    represented by the Counter.

Danyliw Standards Track [Page 74] RFC 7970 IODEF Version 2 November 2016

 duration
    Optional.  ENUM.  If present, the Counter class represents a rate.
    This attribute specifies a unit of time over which the rate whose
    units are specified in the unit attribute is being conveyed.  This
    attribute is the denominator of the rate (where the unit attribute
    specified the nominator).  The possible values of this attribute
    are defined in the duration attribute of Section 3.12.3
 ext-duration
    Optional.  STRING.  A means by which to extend the duration
    attribute.  See Section 5.1.1.

3.19. DomainData Class

 The DomainData class describes a domain name and metadata associated
 with this domain.
 +--------------------------+
 | DomainData               |
 +--------------------------+
 | ENUM system-status       |<>----------[ Name                 ]
 | STRING ext-system-status |<>--{0..1}--[ DateDomainWasChecked ]
 | ENUM domain-status       |<>--{0..1}--[ RegistrationDate     ]
 | STRING ext-domain-status |<>--{0..1}--[ ExpirationDate       ]
 | ID observable-id         |<>--{0..*}--[ RelatedDNS           ]
 |                          |<>--{0..*}--[ Nameservers          ]
 |                          |<>--{0..1}--[ DomainContacts       ]
 +--------------------------+
                    Figure 38: The DomainData Class
 The aggregate classes of the DomainData class are:
 Name
    One.  STRING.  The domain name of a system.
 DateDomainWasChecked
    Zero or one.  DATETIME.  A timestamp of when the domain listed in
    the Name class was resolved.
 RegistrationDate
    Zero or one.  DATETIME.  A timestamp of when domain listed in the
    Name class was registered.
 ExpirationDate
    Zero or one.  DATETIME.  A timestamp of when the domain listed in
    the Name class is set to expire.

Danyliw Standards Track [Page 75] RFC 7970 IODEF Version 2 November 2016

 RelatedDNS
    Zero or more.  EXTENSION.  Additional DNS records associated with
    this domain.
 Nameservers
    Zero or more.  The nameservers identified for the domain listed in
    the Name class.  See Section 3.19.1.
 DomainContacts
    Zero or one.  Contact information for the domain listed in the
    Name class supplied by the registrar or through a whois query.
 The attributes of the DomainData class are:
 system-status
    Required.  ENUM.  Assesses the domain's involvement in the event.
    These values are maintained in the "DomainData-system-status" IANA
    registry per Section 10.2.
    1.  spoofed.  This domain was spoofed.
    2.  fraudulent.  This domain was operated with fraudulent
        intentions.
    3.  innocent-hacked.  This domain was compromised by a third
        party.
    4.  innocent-hijacked.  This domain was deliberately hijacked.
    5.  unknown.  No categorization for this domain known.
    6.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-system-status
    Optional.  STRING.  A means by which to extend the system-status
    attribute.  See Section 5.1.1.
 domain-status
    Required.  ENUM.  Categorizes the registry status of the domain at
    the time the document was generated.  These values and their
    associated descriptions are derived from Section 3.2.2 of
    [RFC3982].  These values are maintained in the
    "DomainData-domain-status" IANA registry per Section 10.2.
    1.   reservedDelegation.  The domain is permanently inactive.

Danyliw Standards Track [Page 76] RFC 7970 IODEF Version 2 November 2016

    2.   assignedAndActive.  The domain is in a normal state.
    3.   assignedAndInactive.  The domain has an assigned
         registration, but the delegation is inactive.
    4.   assignedAndOnHold.  The domain is in dispute.
    5.   revoked.  The domain is in the process of being purged from
         the database.
    6.   transferPending.  The domain is pending a change in
         authority.
    7.   registryLock.  The domain is on hold by the registry.
    8.   registrarLock.  Same as "registryLock".
    9.   other.  The domain has a known status, but it is not one of
         the redefined enumerated values.
    10.  unknown.  The domain has an unknown status.
    11.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-domain-status
    Optional.  STRING.  A means by which to extend the domain-status
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.19.1. Nameservers Class

 The Nameservers class describes the nameservers associated with a
 given domain.
 +--------------------+
 | Nameservers        |
 +--------------------+
 |                    |<>----------[ Server  ]
 |                    |<>--{1..*}--[ Address ]
 +--------------------+
                   Figure 39: The Nameservers Class

Danyliw Standards Track [Page 77] RFC 7970 IODEF Version 2 November 2016

 The aggregate classes of the Nameservers class are:
 Server
    One.  STRING.  The domain name of the nameserver.
 Address
    One or more.  The address of the nameserver.  The value of the
    category attribute MUST be either "ipv4-addr" or "ipv6-addr".  See
    Section 3.18.1.
 The Nameservers class has no attributes.

3.19.2. DomainContacts Class

 The DomainContacts class describes the contact information for a
 given domain provided either by the registrar or through a whois
 query.
 This contact information can be explicitly described through a
 Contact class, or a reference can be provided to a domain with
 identical contact information.  Either a single SameDomainContact or
 one or more Contact classes MUST be present.
 +--------------------+
 | DomainContacts     |
 +--------------------+
 |                    |<>--{0..1}--[ SameDomainContact ]
 |                    |<>--{1..*}--[ Contact ]
 +--------------------+
                  Figure 40: The DomainContacts Class
 The aggregate classes of the DomainContacts class are:
 SameDomainContact
    Zero or one.  STRING.  A domain name already cited in this
    document or through previous exchange that contains the identical
    contact information as the domain name in question.  The domain
    contact information associated with this domain should be used
    instead of an explicit definition with the Contact class.
 Contact
    One or more.  Contact information for the domain.  See
    Section 3.9.
 The DomainContacts class has no attributes.

Danyliw Standards Track [Page 78] RFC 7970 IODEF Version 2 November 2016

3.20. Service Class

 The Service class describes a network service.  The service is
 described by a protocol, port, protocol header field, and application
 providing or using the service.
 +-------------------------+
 | Service                 |
 +-------------------------+
 | INTEGER ip-protocol     |<>--{0..1}--[ ServiceName       ]
 | ID observable-id        |<>--{0..1}--[ Port              ]
 |                         |<>--{0..1}--[ Portlist          ]
 |                         |<>--{0..1}--[ ProtoCode         ]
 |                         |<>--{0..1}--[ ProtoType         ]
 |                         |<>--{0..1}--[ ProtoField        ]
 |                         |<>--{0..1}--[ ApplicationHeader ]
 |                         |<>--{0..1}--[ EmailData         ]
 |                         |<>--{0..1}--[ Application       ]
 +-------------------------+
                     Figure 41: The Service Class
 The aggregate classes of the Service class are:
 ServiceName
    Zero or one.  A protocol name.
 Port
    Zero or one.  INTEGER.  A port number.
 Portlist
    Zero or one.  PORTLIST.  A list of port numbers.
 ProtoCode
    Zero or one.  INTEGER.  A transport-layer (Layer 4) protocol-
    specific code field (e.g., ICMP code field).
 ProtoType
    Zero or one.  INTEGER.  A transport-layer (Layer 4) protocol-
    specific type field (e.g., ICMP type field).
 ProtoField
    Zero or one.  INTEGER.  A transport-layer (Layer 4) protocol-
    specific flag field (e.g., TCP flag field).
 ApplicationHeader
    Zero or one.  A protocol header.  See Section 3.20.2.

Danyliw Standards Track [Page 79] RFC 7970 IODEF Version 2 November 2016

 EmailData
    Zero or one.  Headers associated with an email message.  See
    Section 3.21.
 Application
    Zero or one.  SOFTWARE.  The application acting as either the
    client or the server for the service.
 At least one of these classes MUST be present.
 When a given System class with category="source" and another with
 category="target" are aggregated into a single Flow class, and each
 of these System classes has a Service and Portlist class, an implicit
 relationship between these Portlists exists.  If N ports are listed
 for a System@category="source", and M ports are listed for
 System@category="target", the number of ports in N must be equal to
 M.  Likewise, the ports MUST be listed in an identical sequence such
 that the n-th port in the source corresponds to the n-th port of the
 target.  If N is greater than 1, a given instance of a Flow class
 MUST only have a single instance of a System@category="source" and
 System@category="target".
 The attributes of the Service class are:
 ip-protocol
    Optional.  INTEGER.  The IANA-assigned IP protocol number per
    [IANA.Protocols].  The attribute MUST be set if a Port, Portlist,
    ProtoCode, ProtoType, or ProtoField class is present.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.20.1. ServiceName Class

 The ServiceName class identifies an application protocol.  It can be
 described by referencing an IANA-registered protocol, by referencing
 a URL, or with free-form text.
 +--------------------+
 | ServiceName        |
 +--------------------+
 |                    |<>--{0..1}--[ IANAService       ]
 |                    |<>--{0..*}--[ URL               ]
 |                    |<>--{0..*}--[ Description       ]
 +--------------------+
                   Figure 42: The ServiceName Class

Danyliw Standards Track [Page 80] RFC 7970 IODEF Version 2 November 2016

 The aggregate classes of the ServiceName class are:
 IANAService
    Zero or one.  STRING.  The name of the service per the "Service
    Name" field of the registry [IANA.Ports].
 URL
    Zero or more.  URL.  A URL to a resource describing the service.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    service.
 At least one of these classes MUST be present.
 The ServiceName class has no attributes.

3.20.2. ApplicationHeader Class

 The ApplicationHeader class describes arbitrary fields from a
 protocol header and its corresponding value.
 +--------------------------+
 | ApplicationHeader        |
 +--------------------------+
 |                          |<>--{1..*}--[ ApplicationHeaderField ]
 +--------------------------+
                Figure 43: The ApplicationHeader Class
 The aggregate class of the ApplicationHeader class is:
 ApplicationHeaderField
    One or more.  EXTENSION.  A field name and value in a protocol
    header.  The name attribute MUST be set to the field name.  The
    field value MUST be set in the element content.
 The ApplicationHeader class has no attributes.

Danyliw Standards Track [Page 81] RFC 7970 IODEF Version 2 November 2016

3.21. EmailData Class

 The EmailData class describes headers from an email message and
 cryptographic hashes and signatures applied to it.
 +-------------------------+
 | EmailData               |
 +-------------------------+
 | ID observable-id        |<>--{0..*}--[ EmailTo          ]
 |                         |<>--{0..1}--[ EmailFrom        ]
 |                         |<>--{0..1}--[ EmailSubject     ]
 |                         |<>--{0..1}--[ EmailX-Mailer    ]
 |                         |<>--{0..*}--[ EmailHeaderField ]
 |                         |<>--{0..1}--[ EmailHeaders     ]
 |                         |<>--{0..1}--[ EmailBody        ]
 |                         |<>--{0..1}--[ EmailMessage     ]
 |                         |<>--{0..*}--[ HashData         ]
 |                         |<>--{0..*}--[ SignatureData    ]
 +-------------------------+
                      Figure 44: EmailData Class
 The aggregate classes of the EmailData class are:
 EmailTo
    Zero or more.  EMAIL.  The value of the "To:" header field
    (Section 3.6.3 of [RFC5322]) in an email.
 EmailFrom
    Zero or one.  EMAIL.  The value of the "From:" header field
    (Section 3.6.2 of [RFC5322]) in an email.
 EmailSubject
    Zero or one.  STRING.  The value of the "Subject:" header field in
    an email.  See Section 3.6.5 of [RFC5322].
 EmailX-Mailer
    Zero or one.  STRING.  The value of the "X-Mailer:" header field
    in an email.
 EmailHeaderField
    Zero or more.  EXTENSION.  The header name and value of an
    arbitrary header field of the email message.  The name attribute
    MUST be set to the header name.  The header value MUST be set in
    the element body.  The dtype attribute MUST be set to "string".
 EmailHeaders
    Zero or one.  STRING.  The headers of an email message.

Danyliw Standards Track [Page 82] RFC 7970 IODEF Version 2 November 2016

 EmailBody
    Zero or one.  STRING.  The body of an email message.
 EmailMessage
    Zero or one.  STRING.  The headers and body of an email message.
 HashData
    Zero or more.  Hash(es) associated with this email message.  See
    Section 3.26.
 SignatureData
    Zero or more.  Signature(s) associated with this email message.
    See Section 3.27.
 The attribute of the EmailData class is:
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.22. Record Class

 The Record class is a container class for log and audit data that
 provides supportive information about the events in an incident.  The
 source of this data will often be the output of monitoring tools.
 These logs substantiate the activity described in the document.
 +------------------------+
 | Record                 |
 +------------------------+
 | ENUM restriction       |<>--{1..*}--[ RecordData ]
 | STRING ext-restriction |
 +------------------------+
                      Figure 45: The Record Class
 The aggregate classes of the Record class are:
 RecordData
    One or more.  Log or audit data generated by a particular tool.
    Separate instances of the RecordData class SHOULD be used for each
    type of log.  See Section 3.22.1.
 The attributes of the Record class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.

Danyliw Standards Track [Page 83] RFC 7970 IODEF Version 2 November 2016

 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.22.1. RecordData Class

 The RecordData class describes or references log or audit data from a
 given type of tool and provides a means to annotate the output.
 +------------------------+
 | RecordData             |
 +------------------------+
 | ENUM restriction       |<>--{0..1}--[ DateTime               ]
 | STRING ext-restriction |<>--{0..*}--[ Description            ]
 | ID observable-id       |<>--{0..1}--[ Application            ]
 |                        |<>--{0..*}--[ RecordPattern          ]
 |                        |<>--{0..*}--[ RecordItem             ]
 |                        |<>--{0..*}--[ URL                    ]
 |                        |<>--{0..*}--[ FileData               ]
 |                        |<>--{0..*}--
 |                        |       [ WindowsRegistryKeysModified ]
 |                        |<>--{0..*}--[ CertificateData        ]
 |                        |<>--{0..*}--[ AdditionalData         ]
 +------------------------+
                    Figure 46: The RecordData Class
 The aggregate classes of the RecordData class are:
 DateTime
    Zero or one.  DATETIME.  A timestamp of the data found in the
    RecordItem or URL classes.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    data provided in the RecordItem or URL classes.
 Application
    Zero or one.  SOFTWARE.  Identifies the tool used to generate the
    data in the RecordItem or URL classes.
 RecordPattern
    Zero or more.  A search string to precisely find the relevant data
    in the RecordItem or URL classes.  See Section 3.22.2.
 RecordItem
    Zero or more.  EXTENSION.  Log, audit, or forensic data to support
    the conclusions made during the course of analyzing the incident.

Danyliw Standards Track [Page 84] RFC 7970 IODEF Version 2 November 2016

 URL
    Zero or more.  URL.  A URL reference to a log or audit data.
 FileData
    Zero or one.  The files involved in the incident.  See
    Section 3.25.
 WindowsRegistryKeysModified
    Zero or more.  The registry keys that were involved in the
    incident.  See Section 3.23.
 CertificateData
    Zero or more.  The certificates that were involved in the
    incident.  See Section 3.24.
 AdditionalData
    Zero or more.  EXTENSION.  An extension mechanism for data not
    explicitly represented in the data model.
 At least one of the following classes MUST be present: RecordItem,
 URL, FileData, WindowsRegistryKeysModified, CertificateData, or
 AdditionalData.
 The attributes of the RecordData class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.22.2. RecordPattern Class

 The RecordPattern class describes where in the log data provided or
 referenced in the RecordData class relevant information can be found.
 It provides a way to reference subsets of information, identified by
 a pattern, in a large log file, audit trail, or forensic data.

Danyliw Standards Track [Page 85] RFC 7970 IODEF Version 2 November 2016

 +-----------------------+
 | RecordPattern         |
 +-----------------------+
 | STRING                |
 |                       |
 | ENUM type             |
 | STRING ext-type       |
 | INTEGER offset        |
 | ENUM offsetunit       |
 | STRING ext-offsetunit |
 | INTEGER instance      |
 +-----------------------+
                  Figure 47: The RecordPattern Class
 The content of the class is of type STRING and specifies a search
 pattern.
 The attributes of the RecordPattern class are:
 type
    Required.  ENUM.  Describes the type of pattern being specified in
    the element content.  The default is "regex".  These values are
    maintained in the "RecordPattern-type" IANA registry per
    Section 10.2.
    1.  regex.  Regular expression as defined by POSIX Extended
        Regular Expressions (ERE) in Chapter 9 of [IEEE.POSIX].
    2.  binary.  Binhex-encoded binary pattern, per the HEXBIN data
        type.
    3.  xpath.  XML Path (XPath) [W3C.XPATH].
    4.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.
 offset
    Optional.  INTEGER.  Amount of units (determined by the offsetunit
    attribute) to seek into the RecordItem data before matching the
    pattern.

Danyliw Standards Track [Page 86] RFC 7970 IODEF Version 2 November 2016

 offsetunit
    Optional.  ENUM.  Describes the units of the offset attribute.
    The default is "line".  These values are maintained in the
    "RecordPattern-offsetunit" IANA registry per Section 10.2.
    1.  line.  Offset is a count of lines.
    2.  byte.  Offset is a count of bytes.
    3.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-offsetunit
    Optional.  STRING.  A means by which to extend the offsetunit
    attribute.  See Section 5.1.1.
 instance
    Optional.  INTEGER.  Number of times to apply the specified
    pattern.

3.23. WindowsRegistryKeysModified Class

 The WindowsRegistryKeysModified class describes Windows operating
 system registry keys and the operations that were performed on them.
 This class was derived from [RFC5901].
 +-----------------------------+
 | WindowsRegistryKeysModified |
 +-----------------------------+
 | ID observable-id            |<>--{1..*}--[ Key ]
 +-----------------------------+
           Figure 48: The WindowsRegistryKeysModified Class
 The aggregate classes of the WindowsRegistryKeysModified class are:
 Key
    One or more.  The Windows registry key.  See Section 3.23.1.
 The attribute of the WindowsRegistryKeysModified class is:
 observable-id
    Optional.  ID.  See Section 3.3.2.

Danyliw Standards Track [Page 87] RFC 7970 IODEF Version 2 November 2016

3.23.1. Key Class

 The Key class describes a Windows operating system registry key name
 and value pair, as well as the operation performed on it.
 +---------------------------+
 | Key                       |
 +---------------------------+
 | ENUM registryaction       |<>----------[ KeyName  ]
 | STRING ext-registryaction |<>--{0..1}--[ KeyValue ]
 | ID observable-id          |
 +---------------------------+
                       Figure 49: The Key Class
 The aggregate classes of the Key class are:
 KeyName
    One.  STRING.  The name of a Windows operating system registry key
    (e.g., [HKEY_LOCAL_MACHINE\Software\Test\KeyName]).
 KeyValue
    Zero or one.  STRING.  The value of the registry key identified in
    the KeyName class encoded per the .reg file format [KB310516].
 The attributes of the Key class are:
 registryaction
    Optional.  ENUM.  The type of action taken on the registry key.
    These values are maintained in the "Key-registryaction" IANA
    registry per Section 10.2.
    1.  add-key.  Registry key added.
    2.  add-value.  Value added to a registry key.
    3.  delete-key.  Registry key deleted.
    4.  delete-value.  Value deleted from a registry key.
    5.  modify-key.  Registry key modified.
    6.  modify-value.  Value modified in a registry key.
    7.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 88] RFC 7970 IODEF Version 2 November 2016

 ext-registryaction
    Optional.  STRING.  A means by which to extend the registryaction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.24. CertificateData Class

 The CertificateData class describes X.509 certificates.
 +------------------------+
 | CertificateData        |
 +------------------------+
 | ENUM restriction       |<>--{1..*}--[ Certificate    ]
 | STRING ext-restriction |
 | ID observable-id       |
 +------------------------+
                 Figure 50: The CertificateData Class
 The aggregate classes of the CertificateData class are:
 Certificate
    One or more.  A description of an X.509 certificate or certificate
    chain.  See Section 3.24.1.
 The attributes of the CertificateData class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

Danyliw Standards Track [Page 89] RFC 7970 IODEF Version 2 November 2016

3.24.1. Certificate Class

 The Certificate class describes a given X.509 certificate or
 certificate chain.
 +--------------------------+
 | Certificate              |
 +--------------------------+
 | ID observable-id         |<>----------[ ds:X509Data    ]
 |                          |<>--{0..*}--[ Description    ]
 +--------------------------+
                   Figure 51: The Certificate Class
 The aggregate classes of the Certificate class are:
 ds:X509Data
    One.  A given X.509 certificate or chain.  See Section 4.4.4 of
    [W3C.XMLSIG].
 Description
    Zero or more.  ML_STRING.  A free-form text description explaining
    the context of this certificate.
 The attributes of the Certificate class are:
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.25. FileData Class

 The FileData class describes a file or set of files.
 +------------------------+
 | FileData               |
 +------------------------+
 | ENUM restriction       |<>--{1..*}--[ File      ]
 | STRING ext-restriction |
 | ID observable-id       |
 +------------------------+
                     Figure 52: The FileData Class
 The aggregate classes of the FileData class are:
 File
    One or more.  A description of a file.  See Section 3.25.1.

Danyliw Standards Track [Page 90] RFC 7970 IODEF Version 2 November 2016

 The attributes of the FileData class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.25.1. File Class

 The File class describes a file; its associated metadata; and
 cryptographic hashes and signatures applied to it.
 +-----------------------+
 | File                  |
 +-----------------------+
 | ID observable-id      |<>--{0..1}--[ FileName           ]
 |                       |<>--{0..1}--[ FileSize           ]
 |                       |<>--{0..1}--[ FileType           ]
 |                       |<>--{0..*}--[ URL                ]
 |                       |<>--{0..1}--[ HashData           ]
 |                       |<>--{0..1}--[ SignatureData      ]
 |                       |<>--{0..1}--[ AssociatedSoftware ]
 |                       |<>--{0..*}--[ FileProperties     ]
 +-----------------------+
                       Figure 53: The File Class
 The aggregate classes of the File class are:
 FileName
    Zero or one.  STRING.  The name of the file.
 FileSize
    Zero or one.  INTEGER.  The size of the file in bytes.
 FileType
    Zero or one.  STRING.  The type of file per the IANA "Media Types"
    registry [IANA.Media].  Valid values correspond to the text in the
    "Template" column (e.g., "application/pdf").
 URL
    Zero or more.  URL.  A URL reference to the file.

Danyliw Standards Track [Page 91] RFC 7970 IODEF Version 2 November 2016

 HashData
    Zero or one.  Hash(es) associated with this file.  See
    Section 3.26.
 SignatureData
    Zero or one.  Signature(s) associated with this file.  See
    Section 3.27.
 AssociatedSoftware
    Zero or one.  SOFTWARE.  The software application or operating
    system to which this file belongs or by which it can be processed.
 FileProperties
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model to describe properties of the file.
 The attributes of the File class are:
 observable-id
    Optional.  ID.  See Section 3.3.2.

3.26. HashData Class

 The HashData class describes different types of hashes on a given
 object (e.g., file, part of a file, email).
 +--------------------------+
 | HashData                 |
 +--------------------------+
 | ENUM scope               |<>--{0..1}--[ HashTargetID ]
 |                          |<>--{0..*}--[ Hash         ]
 |                          |<>--{0..*}--[ FuzzyHash    ]
 +--------------------------+
                     Figure 54: The HashData Class
 The aggregate classes of the HashData class are:
 HashTargetID
    Zero or one.  STRING.  An identifier that references a subset of
    the object being hashed.  The semantics of this identifier are
    specified by the scope attribute.
 Hash
    Zero or more.  The hash of an object.  See Section 3.26.1.
 FuzzyHash
    Zero or more.  The fuzzy hash of an object.  See Section 3.26.2.

Danyliw Standards Track [Page 92] RFC 7970 IODEF Version 2 November 2016

 At least one instance of either Hash or FuzzyHash MUST be present.
 The attribute of the HashData class is:
 scope
    Required.  ENUM.  Describes on which part of the object the hash
    should be applied.  These values are maintained in the "HashData-
    scope" IANA registry per Section 10.2.
    1.  file-contents.  A hash computed over the entire contents of a
        file.
    2.  file-pe-section.  A hash computed on a given section of a
        Windows Portable Executable (PE) file.  If set to this value,
        the HashTargetID class MUST identify the section being hashed.
        A section is identified by an ordinal number (starting at 1)
        corresponding to the order in which the given section header
        was defined in the Section Table of the PE file header.
    3.  file-pe-iat.  A hash computed on the Import Address
        Table (IAT) of a PE file.  As IAT hashes are often tool
        dependent, if this value is set, the Application class of
        either the Hash or FuzzyHash classes MUST specify the tool
        used to generate the hash.
    4.  file-pe-resource.  A hash computed on a given resource in a PE
        file.  If set to this value, the HashTargetID class MUST
        identify the resource being hashed.  A resource is identified
        by an ordinal number (starting at 1) corresponding to the
        order in which the given resource is declared in the Resource
        Directory of the Data Dictionary in the PE file header.
    5.  file-pdf-object.  A hash computed on a given object in a
        Portable Document Format (PDF) file.  If set to this value,
        the HashTargetID class MUST identify the object being hashed.
        This object is identified by its offset in the PDF file.
    6.  email-hash.  A hash computed over the headers and body of an
        email message.
    7.  email-headers-hash.  A hash computed over all of the headers
        of an email message.
    8.  email-body-hash.  A hash computed over the body of an email
        message.

Danyliw Standards Track [Page 93] RFC 7970 IODEF Version 2 November 2016

    9.  ext-value.  A value used to indicate that this attribute is
        extended and the actual value is provided using the
        corresponding ext-* attribute.  See Section 5.1.1.
 ext-scope
    Optional.  STRING.  A means by which to extend the scope
    attribute.  See Section 5.1.1.

3.26.1. Hash Class

 The Hash class describes a cryptographic hash value; the algorithm
 and application used to generate it; and the canonicalization method
 applied to the object being hashed.
 +----------------+
 | Hash           |
 +----------------+
 |                |<>----------[ ds:DigestMethod            ]
 |                |<>----------[ ds:DigestValue             ]
 |                |<>--{0..1}--[ ds:CanonicalizationMethod  ]
 |                |<>--{0..1}--[ Application                ]
 +----------------+
                       Figure 55: The Hash Class
 The aggregate classes of the Hash class are:
 ds:DigestMethod
    One.  The hash algorithm used to generate the hash.  See
    Section 4.3.3.5 of [W3C.XMLSIG].
 ds:DigestValue
    One.  The computed hash value.  See Section 4.3.3.6 of
    [W3C.XMLSIG].
 ds:CanonicalizationMethod
    Zero or one.  The canonicalization method used on the object being
    hashed.  See Section 4.3.1 of [W3C.XMLSIG].
 Application
    Zero or one.  SOFTWARE.  The application used to calculate the
    hash.
 The HashData class has no attributes.

Danyliw Standards Track [Page 94] RFC 7970 IODEF Version 2 November 2016

3.26.2. FuzzyHash Class

 The FuzzyHash class describes a fuzzy hash and the application used
 to generate it.
 +--------------------------+
 | FuzzyHash                |
 +--------------------------+
 |                          |<>--{1..*}--[ FuzzyHashValue ]
 |                          |<>--{0..1}--[ Application    ]
 |                          |<>--{0..*}--[ AdditionalData ]
 +--------------------------+
                    Figure 56: The FuzzyHash Class
 The aggregate classes of the FuzzyHash class are:
 FuzzyHashValue
    One or more.  EXTENSION.  The computed fuzzy hash value.
 Application
    Zero or one.  SOFTWARE.  The application used to calculate the
    hash.
 AdditionalData
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model.
 The FuzzyData class has no attributes.

3.27. SignatureData Class

 The SignatureData class describes different types of digital
 signatures on an object.
 +--------------------------+
 | SignatureData            |
 +--------------------------+
 |                          |<>--{1..*}--[ ds:Signature ]
 +--------------------------+
                  Figure 57: The SignatureData Class

Danyliw Standards Track [Page 95] RFC 7970 IODEF Version 2 November 2016

 The aggregate class of the SignatureData class is:
 Signature
    One or more.  A given signature.  See Section 4.2 of [W3C.XMLSIG].
 The SignatureData class has no attributes.

3.28. IndicatorData Class

 The IndicatorData class describes indicators and metadata associated
 with them.
 +--------------------------+
 | IndicatorData            |
 +--------------------------+
 |                          |<>--{1..*}--[ Indicator      ]
 +--------------------------+
                  Figure 58: The IndicatorData Class
 The aggregate class of the IndicatorData class is:
 Indicator
    One or more.  A description of an indicator.  See Section 3.29.
 The IndicatorData class has no attributes.

3.29. Indicator Class

 The Indicator class describes an indicator.  An indicator consists of
 observable features and phenomenon that aid in the forensic or
 proactive detection of malicious activity and associated metadata.
 An indicator can be described outright by referencing or composing
 previously defined indicators or by referencing observables described
 in the incident report found in this document.

Danyliw Standards Track [Page 96] RFC 7970 IODEF Version 2 November 2016

 +------------------------+
 | Indicator              |
 +------------------------+
 | ENUM restriction       |<>----------[ IndicatorID            ]
 | STRING ext-restriction |<>--{0..*}--[ AlternativeIndicatorID ]
 |                        |<>--{0..*}--[ Description            ]
 |                        |<>--{0..1}--[ StartTime              ]
 |                        |<>--{0..1}--[ EndTime                ]
 |                        |<>--{0..1}--[ Confidence             ]
 |                        |<>--{0..*}--[ Contact                ]
 |                        |<>--{0..1}--[ Observable             ]
 |                        |<>--{0..1}--[ ObservableReference    ]
 |                        |<>--{0..1}--[ IndicatorExpression    ]
 |                        |<>--{0..1}--[ IndicatorReference     ]
 |                        |<>--{0..*}--[ NodeRole               ]
 |                        |<>--{0..*}--[ AttackPhase            ]
 |                        |<>--{0..*}--[ Reference              ]
 |                        |<>--{0..*}--[ AdditionalData         ]
 +------------------------+
                    Figure 59: The Indicator Class
 The aggregate classes of the Indicator class are:
 IndicatorID
    One.  An identifier for this indicator.  See Section 3.29.1.
 AlternativeIndicatorID
    Zero or more.  An alternative identifier for this indicator.  See
    Section 3.29.2.
 Description
    Zero or more.  ML_STRING.  A free-form text description of the
    indicator.
 StartTime
    Zero or one.  DATETIME.  A timestamp of the start of the time
    period during which this indicator is valid.
 EndTime
    Zero or one.  DATETIME.  A timestamp of the end of the time period
    during which this indicator is valid.
 Confidence
    Zero or one.  An estimate of the confidence in the quality of the
    indicator.  See Section 3.12.5.

Danyliw Standards Track [Page 97] RFC 7970 IODEF Version 2 November 2016

 Contact
    Zero or more.  Contact information for this indicator.  See
    Section 3.9.
 Observable
    Zero or one.  An observable feature or phenomenon of this
    indicator.  See Section 3.29.3.
 ObservableReference
    Zero or one.  A reference to an observable feature or phenomenon
    defined elsewhere in the document.  See Section 3.29.6.
 IndicatorExpression
    Zero or one.  A composition of observables.  See Section 3.29.4.
 IndicatorReference
    Zero or one.  A reference to an indicator.  See Section 3.29.7.
 NodeRole
    Zero or more.  The role of the system in the attack should this
    indicator be matched to it.  See Section 3.18.2.
 AttackPhase
    Zero or more.  The phase in an attack life cycle during which this
    indicator might be seen.  See Section 3.29.8.
 Reference
    Zero or more.  A reference to additional information relevant to
    this indicator.  See Section 3.11.1.
 AdditionalData
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model.
 The Indicator class MUST have exactly one instance of an Observable,
 IndicatorExpression, ObservableReference, or IndicatorReference
 class.
 The StartTime and EndTime classes can be used to define an interval
 during which the indicator is valid.  If both classes are present,
 the indicator is consider valid only during the described interval.
 If neither class is provided, the indicator is considered valid
 during any time interval.  If only a StartTime is provided, the
 indicator is valid anytime after this timestamp.  If only an EndTime
 is provided, the indicator is valid anytime prior to this timestamp.

Danyliw Standards Track [Page 98] RFC 7970 IODEF Version 2 November 2016

 The attributes of the Indicator class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.29.1. IndicatorID Class

 The IndicatorID class identifies an indicator with a globally unique
 identifier.  The combination of the name and version attributes and
 the element content form this identifier.  Indicators generated by
 given CSIRT MUST NOT reuse the same value unless they are referencing
 the same indicator.
 +------------------+
 | IndicatorID      |
 +------------------+
 | ID               |
 |                  |
 | STRING name      |
 | STRING version   |
 +------------------+
                   Figure 60: The IndicatorID Class
 The content of the class is of type ID and specifies an identifier
 for an indicator.
 The attributes of the IndicatorID class are:
 name
    Required.  STRING.  An identifier describing the CSIRT that
    created the indicator.  In order to have a globally unique CSIRT
    name, the fully qualified domain name associated with the CSIRT
    MUST be used.  This format is identical to the IncidentID@name
    attribute in Section 3.4.
 version
    Required.  STRING.  A version number of an indicator.

Danyliw Standards Track [Page 99] RFC 7970 IODEF Version 2 November 2016

3.29.2. AlternativeIndicatorID Class

 The AlternativeIndicatorID class lists alternative identifiers for an
 indicator.
 +-------------------------+
 | AlternativeIndicatorID  |
 +-------------------------+
 | ENUM restriction        |<>--{1..*}--[ IndicatorReference ]
 | STRING ext-restriction  |
 +-------------------------+
              Figure 61: The AlternativeIndicatorID Class
 The aggregate class of the AlternativeIndicatorID class is:
 IndicatorReference
    One or more.  A reference to an indicator.  See Section 3.29.7.
 The attributes of the AlternativeIndicatorID class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

Danyliw Standards Track [Page 100] RFC 7970 IODEF Version 2 November 2016

3.29.3. Observable Class

 The Observable class describes a feature and phenomenon that can be
 observed or measured for the purposes of detecting malicious
 behavior.
 +------------------------+
 | Observable             |
 +------------------------+
 | ENUM restriction       |<>--{0..1}--[ System                      ]
 | STRING ext-restriction |<>--{0..1}--[ Address                     ]
 |                        |<>--{0..1}--[ DomainData                  ]
 |                        |<>--{0..1}--[ Service                     ]
 |                        |<>--{0..1}--[ EmailData                   ]
 |                        |<>--{0..1}--[ WindowsRegistryKeysModified ]
 |                        |<>--{0..1}--[ FileData                    ]
 |                        |<>--{0..1}--[ CertificateData             ]
 |                        |<>--{0..1]--[ RegistryHandle              ]
 |                        |<>--{0..1}--[ RecordData                  ]
 |                        |<>--{0..1}--[ EventData                   ]
 |                        |<>--{0..1}--[ Incident                    ]
 |                        |<>--{0..1}--[ Expectation                 ]
 |                        |<>--{0..1}--[ Reference                   ]
 |                        |<>--{0..1}--[ Assessment                  ]
 |                        |<>--{0..1}--[ DetectionPattern            ]
 |                        |<>--{0..1}--[ HistoryItem                 ]
 |                        |<>--{0..1}--[ BulkObservable              ]
 |                        |<>--{0..*}--[ AdditionalData              ]
 +------------------------+
                    Figure 62: The Observable Class
 The aggregate classes of the Observable class are:
 System
    Zero or one.  A System observable.  See Section 3.17.
 Address
    Zero or one.  An Address observable.  See Section 3.18.1.
 DomainData
    Zero or one.  A DomainData observable.  See Section 3.19.
 Service
    Zero or one.  A Service observable.  See Section 3.20.
 EmailData
    Zero or one.  An EmailData observable.  See Section 3.21.

Danyliw Standards Track [Page 101] RFC 7970 IODEF Version 2 November 2016

 WindowsRegistryKeysModified
    Zero or one.  A WindowsRegistryKeysModified observable.  See
    Section 3.23.
 FileData
    Zero or one.  A FileData observable.  See Section 3.25.
 CertificateData
    Zero or one.  A CertificateData observable.  See Section 3.24.
 RegistryHandle
    Zero or one.  A RegistryHandle observable.  See Section 3.9.1.
 RecordData
    Zero or one.  A RecordData observable.  See Section 3.22.1.
 EventData
    Zero or one.  An EventData observable.  See Section 3.14.
 Incident
    Zero or one.  An Incident observable.  See Section 3.2.
 Expectation
    Zero or one.  An Expectation observable.  See Section 3.15.
 Reference
    Zero or one.  A Reference observable.  See Section 3.11.1.
 Assessment
    Zero or one.  An Assessment observable.  See Section 3.12.
 DetectionPattern
    Zero or one.  A DetectionPattern observable.  See Section 3.10.1.
 HistoryItem
    Zero or one.  A HistoryItem observable.  See Section 3.13.1.
 BulkObservable
    Zero or one.  A bulk list of observables.  See Section 3.29.3.1.
 AdditionalData
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model.
 The Observable class MUST have exactly one of the possible child
 classes.

Danyliw Standards Track [Page 102] RFC 7970 IODEF Version 2 November 2016

 The attributes of the Observable class are:
 restriction
    Optional.  ENUM.  See Section 3.3.1.
 ext-restriction
    Optional.  STRING.  A means by which to extend the restriction
    attribute.  See Section 5.1.1.

3.29.3.1. BulkObservable Class

 The BulkObservable class allows the enumeration of a single type of
 observable without requiring each one to be encoded individually in
 multiple instances of the same class.
 The type attribute describes the type of observable listed in the
 child BulkObservableList class.  The BulkObservableFormat class
 optionally provides additional metadata.
 +---------------------------+
 | BulkObservable            |
 +---------------------------+
 | ENUM type                 |<>--{0..1}--[ BulkObservableFormat ]
 | STRING ext-type           |<>----------[ BulkObservableList   ]
 |                           |<>--{0..*}--[ AdditionalData       ]
 +---------------------------+
                  Figure 63: The BulkObservable Class
 The aggregate classes of the BulkObservable class are:
 BulkObservableFormat
    Zero or one.  Provides additional metadata about the observables
    enumerated in the BulkObservableList class.  See
    Section 3.29.3.1.1.
 BulkObservableList
    One.  STRING.  A list of observables, one per line.  Each line is
    separated with either a LF character or CR and LF characters.  The
    type attribute specifies which observables will be listed.
 AdditionalData
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model.

Danyliw Standards Track [Page 103] RFC 7970 IODEF Version 2 November 2016

 The attributes of the BulkObservable class are:
 type
    Optional.  ENUM.  The type of the observable listed in the child
    ObservableList class.  These values are maintained in the
    "BulkObservable-type" IANA registry per Section 10.2.
    1.   asn.  Autonomous System Number (per the Address@category
         attribute).
    2.   atm.  Asynchronous Transfer Mode (ATM) address (per the
         Address@category attribute).
    3.   e-mail.  Email address (per the Address@category attribute).
    4.   ipv4-addr.  IPv4 host address in dotted-decimal notation,
         e.g., 192.0.2.1 (per the Address@category attribute).
    5.   ipv4-net.  IPv4 network address in dotted-decimal notation,
         slash, significant bits, e.g., 192.0.2.0/24 (per the
         Address@category attribute).
    6.   ipv4-net-mask.  IPv4 network address in dotted-decimal
         notation, slash, network mask in dotted-decimal notation,
         i.e., 192.0.2.0/255.255.255.0 (per the Address@category
         attribute).
    7.   ipv6-addr.  IPv6 host address, e.g., 2001:DB8::3 (per the
         Address@category attribute).
    8.   ipv6-net.  IPv6 network address, slash, significant bits,
         e.g., 2001:DB8::/32 (per the Address@category attribute).
    9.   ipv6-net-mask.  IPv6 network address, slash, network mask
         (per the Address@category attribute).
    10.  mac.  Media Access Control (MAC) address, i.e., a:b:c:d:e:f
         (per the Address@category attribute).
    11.  site-uri.  A URL or URI for a resource (per the
         Address@category attribute).
    12.  domain-name.  A fully qualified domain name or part of a name
         (e.g., fqdn.example.com, example.com).
    13.  domain-to-ipv4.  A mapping of FQDN to IPv4 address specified
         as a comma-separated list (e.g., "fqdn.example.com,
         192.0.2.1").

Danyliw Standards Track [Page 104] RFC 7970 IODEF Version 2 November 2016

    14.  domain-to-ipv6.  A mapping of FQDN to IPv6 address specified
         as a comma-separated list (e.g., "fqdn.example.com,
         2001:DB8::3").
    15.  domain-to-ipv4-timestamp.  Same as domain-to-ipv4 but with a
         timestamp (in the DATETIME format) of the resolution (e.g.,
         "fqdn.example.com, 192.0.2.1, 2015-06-11T00:38:31-06:00").
    16.  domain-to-ipv6-timestamp.  Same as domain-to-ipv6 but with a
         timestamp (in the DATETIME format) of the resolution (e.g.,
         "fqdn.example.com, 2001:DB8::3, 2015-06-11T00:38:31-06:00").
    17.  ipv4-port.  An IPv4 address, port, and protocol tuple (e.g.,
         192.0.2.1, 80, TCP).  The protocol name corresponds to the
         "Keyword" column in the "Assigned Internet Protocol Numbers"
         registry [IANA.Protocols].
    18.  ipv6-port.  An IPv6 address, port, and protocol tuple (e.g.,
         2001:DB8::3, 80, TCP).  The protocol name corresponds to the
         "Keyword" column in the "Assigned Internet Protocol Numbers"
         registry [IANA.Protocols].
    19.  windows-reg-key.  A Microsoft Windows registry key.
    20.  file-hash.  A file hash.  The format of this hash is
         described in the Hash class that MUST be present in a sibling
         BulkObservableFormat class.
    21.  email-x-mailer.  An X-Mailer field from an email.
    22.  email-subject.  An email subject line.
    23.  http-user-agent.  A User Agent field from an HTTP request
         header (e.g., "Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0)
         Gecko/20100101 Firefox/38.0").
    24.  http-request-uri.  The Request URI from an HTTP request
         header.
    25.  mutex.  The name of a system mutex (mutual exclusion lock).
    26.  file-path.  A file path (e.g., "/tmp/local/file",
         "c:\windows\system32\file.sys").
    27.  user-name.  A username.

Danyliw Standards Track [Page 105] RFC 7970 IODEF Version 2 November 2016

    28.  ext-value.  A value used to indicate that this attribute is
         extended and the actual value is provided using the
         corresponding ext-* attribute.  See Section 5.1.1.
 ext-type
    Optional.  STRING.  A means by which to extend the type attribute.
    See Section 5.1.1.

3.29.3.1.1. BulkObservableFormat Class

 The ObservableFormat class specifies metadata about the format of an
 observable enumerated in a sibling BulkObservableList class.
 +---------------------------+
 | BulkObservableFormat      |
 +---------------------------+
 |                           |<>--{0..1}--[ Hash             ]
 |                           |<>--{0..*}--[ AdditionalData   ]
 +---------------------------+
               Figure 64: The BulkObservableFormat Class
 The aggregate classes of the BulkObservableFormat class are:
 Hash
    Zero or one.  Describes the format of a hash.  See Section 3.26.1.
 AdditionalData
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model.
 The BulkObservableFormat class has no attributes.
 Either Hash or AdditionalData MUST be present.

3.29.4. IndicatorExpression Class

 The IndicatorExpression describes an expression composed of observed
 phenomenon, features, or indicators.  Elements of the expression can
 be described directly, reference relevant data from other parts of a
 given IODEF document, or reference previously defined indicators.
 All child classes of a given instance of IndicatorExpression form a
 boolean algebraic expression where the operator between them is
 determined by the operator attribute.

Danyliw Standards Track [Page 106] RFC 7970 IODEF Version 2 November 2016

 +--------------------------+
 | IndicatorExpression      |
 +--------------------------+
 | ENUM operator            |<>--{0..*}--[ IndicatorExpression  ]
 | STRING ext-operator      |<>--{0..*}--[ Observable           ]
 |                          |<>--{0..*}--[ ObservableReference  ]
 |                          |<>--{0..*}--[ IndicatorReference   ]
 |                          |<>--{0..1}--[ Confidence           ]
 |                          |<>--{0..*}--[ AdditionalData       ]
 +--------------------------+
               Figure 65: The IndicatorExpression Class
 The aggregate classes of the IndicatorExpression class are:
 IndicatorExpression
    Zero or more.  An expression composed of other observables or
    indicators.  See Section 3.29.4.
 Observable
    Zero or more.  A description of an observable.  See
    Section 3.29.3.
 ObservableReference
    Zero or more.  A reference to an observable.  See Section 3.29.6.
 IndicatorReference
    Zero or more.  A reference to an indicator.  See Section 3.29.7.
 Confidence
    Zero or one.  An estimate of the confidence in the quality of the
    terms expressed in the expression.  See Section 3.12.5.
 AdditionalData
    Zero or more.  EXTENSION.  Mechanism by which to extend the data
    model.
 The attributes of the IndicatorExpression class are:
 operator
    Optional.  ENUM.  The operator to be applied between the child
    elements.  See Section 3.29.5 for parsing guidance.  The default
    value is "and".  These values are maintained in the
    "IndicatorExpression-operator" IANA registry per Section 10.2.
    1.  not.  negation operator.
    2.  and.  conjunction operator.

Danyliw Standards Track [Page 107] RFC 7970 IODEF Version 2 November 2016

    3.  or.  disjunction operator.
    4.  xor.  exclusive disjunction operator.
 ext-operator
    Optional.  STRING.  A means by which to extend the operator
    attribute.  See Section 5.1.1.

3.29.5. Expressions with IndicatorExpression

 Boolean algebraic expressions can be used to specify relationships
 between observables and indicators.  These expressions are
 constructed through the use of the operator attribute and parent-
 child relationships in IndicatorExpressions.  These expressions
 should be parsed as follows:
 1.  The operator specified by the operator attribute is applied
     between each of the child elements of the immediate parent
     IndicatorExpression element.  If no operator attribute is
     specified, it should be assumed to be the conjunction operator
     (i.e., operator="and").
 2.  A nested IndicatorExpression element with a parent
     IndicatorExpression is the equivalent of a parentheses in the
     expression.
 The following examples in Figures 66 through 70 illustrate these
 parsing rules:
 1     : <IndicatorExpression>
 2 [O1]:    <Observable>..</Observable>
 3 [O2]:    <Observable>..</Observable>
 4     : </IndicatorExpression>
 Equivalent expression: (O1 AND O2)
    Figure 66: Nested Elements in an IndicatorExpression without an
                     Operator Attribute Specified
 1     : <IndicatorExpression operator="or">
 2 [O1]:    <Observable>..</Observable>
 3 [O2]:    <Observable>..</Observable>
 4     : </IndicatorExpression>
 Equivalent expression: (O1 OR O2)
 Figure 67: Nested Elements in an IndicatorExpression with an Operator
                          Attribute Specified

Danyliw Standards Track [Page 108] RFC 7970 IODEF Version 2 November 2016

 1     : <IndicatorExpression operator="or">
 2     :    <IndicatorExpression operator="or">
 3 [O1]:      <Observable>..</Observable>
 4 [O2]:      <Observable>..</Observable>
 5     :    </IndicatorExpression>
 6 [O3]:    <Observable>..</Observable>
 7     : </IndicatorExpression>
 Equivalent expression: ((O1 OR O2) OR O3)
 Figure 68: Nested Elements with a Recursive IndicatorExpression with
                    an Operator Attribute Specified
 1     : <IndicatorExpression operator="not">
 2     :    <IndicatorExpression operator="and">
 3 [O1]:      <Observable>..</Observable>
 4 [O2]:      <Observable>..</Observable>
 5     :    </IndicatorExpression>
 6     : </IndicatorExpression>
 Equivalent expression: (NOT (O1 AND O2))
 Figure 69: A Recursive IndicatorExpression with an Operator Attribute
                               Specified
  1                          :    <IndicatorExpression operator="or">
  2                          :      <IndicatorExpression>
  3 [O1 with low confidence] :        <Observable>..</Observable>
  4                          :        <Confidence rating="low" />
  5                          :      </IndicatorExpression>
  6                          :      <IndicatorExpression>
  7 [O2 with high confidence]:        <Observable>..</Observable>
  8                          :        <Confidence rating="high" />
  9                          :      </IndicatorExpression>
 10                          :    </IndicatorExpression>
 Equivalent expression: ((O1) OR (O2))
        Figure 70: Varying Confidence on Particular Observables
 Invalid algebraic expressions while valid XML MUST NOT be specified.

Danyliw Standards Track [Page 109] RFC 7970 IODEF Version 2 November 2016

3.29.6. ObservableReference Class

 The ObservableReference describes a reference to an observable
 feature or phenomenon described elsewhere in the document.
 The ObservableReference class has no content.
 +-------------------------+
 | ObservableReference     |
 +-------------------------+
 | IDREF uid-ref           |
 +-------------------------+
               Figure 71: The ObservableReference Class
 The ObservableReference class has no content.
 The attribute of the ObservableReference class is:
 uid-ref
    Required.  IDREF.  An identifier that serves as a reference to a
    class in the IODEF document.  The referenced class will have this
    identifier set in its observable-id attribute.

3.29.7. IndicatorReference Class

 The IndicatorReference describes a reference to an indicator.  This
 reference may be to an indicator described in this IODEF document or
 in a previously exchanged IODEF document.
 The IndicatorReference class has no content.
 +--------------------------+
 | IndicatorReference       |
 +--------------------------+
 | IDREF uid-ref            |
 | STRING euid-ref          |
 | STRING version           |
 +--------------------------+
                Figure 72: The IndicatorReference Class
 The attributes of the IndicatorReference class are:
 uid-ref
    Optional.  IDREF.  An identifier that references an Indicator
    class in the IODEF document.  The referenced Indicator class will
    have this identifier set in its IndicatorID class.

Danyliw Standards Track [Page 110] RFC 7970 IODEF Version 2 November 2016

 euid-ref
    Optional.  STRING.  An identifier that references an IndicatorID
    not in this IODEF document.
 version
    Optional.  STRING.  A version number of an indicator.
 Either the uid-ref or the euid-ref attribute MUST be set.

3.29.8. AttackPhase Class

 The AttackPhase class describes a particular phase of an attack life
 cycle.
 +------------------------+
 | AttackPhase            |
 +------------------------+
 |                        |<>--{0..*}--[ AttackPhaseID  ]
 |                        |<>--{0..*}--[ URL            ]
 |                        |<>--{0..*}--[ Description    ]
 |                        |<>--{0..*}--[ AdditionalData ]
 +------------------------+
                   Figure 73: The AttackPhase Class
 The aggregate classes of the AttackPhase class are:
 AttackPhaseID
    Zero or more.  STRING.  An identifier for the phase of the attack.
 URL
    Zero or more.  URL.  A URL to a resource describing this phase of
    the attack.
 Description
    Zero or more.  ML_STRING.  A free-form text description of this
    phase of the attack.
 AdditionalData
    Zero or more.  EXTENSION.  A mechanism by which to extend the data
    model.
 AttackPhase MUST have at least one instance of a child class.
 The AttackPhase class has no attributes.

Danyliw Standards Track [Page 111] RFC 7970 IODEF Version 2 November 2016

4. Processing Considerations

 This section provides additional requirements and guidance on
 creating and processing IODEF documents.

4.1. Encoding

 Every IODEF document MUST begin with an XML declaration and MUST
 specify the XML version used.  The character encoding MUST also be
 explicitly specified.  UTF-8 [RFC3629] SHOULD be used unless UTF-16
 [RFC2781] is necessary.  Encodings other than UTF-8 and UTF-16 SHOULD
 NOT be used.  The IODEF conforms to all XML data-encoding conventions
 and constraints.
 The XML declaration with UTF-8 character encoding will read as
 follows:
 <?xml version="1.0" encoding="UTF-8" ?>
 Certain characters have special meaning in XML and MUST not appear in
 literal form.  Per Section 2.4 of [W3C.XML], these characters MUST be
 escaped with a numeric character or entity reference.

4.2. IODEF Namespace

 The IODEF schema declares a namespace of
 "urn:ietf:params:xml:ns:iodef-2.0" and registers it per [W3C.XMLNS].
 Each IODEF document MUST include a valid reference to the IODEF
 schema using the "xsi:schemaLocation" attribute.  An example of such
 a declaration would look as follows:
 <IODEF-Document
    version="2.00" lang="en-US"
    xmlns:iodef="urn:ietf:params:xml:ns:iodef-2.0"
    xsi:schemaLocation="urn:ietf:params:xmls:schema:iodef-2.0" ...>

4.3. Validation

 IODEF documents MUST be well-formed XML.  It is RECOMMENDED that
 recipients validate the document against the schema described in
 Section 8.  However, mere conformance to this schema is not
 sufficient for a semantically valid IODEF document.  The text of
 Section 3 describes further formatting and constraints, including
 some that cannot be conveniently encoded in the schema.  These MUST
 also be considered by an IODEF implementation.  Furthermore, the
 enumerated values present in this document are a static list that
 will be incomplete over time as select attributes can be extended by
 a corresponding IANA registry per Section 10.2.  Therefore, IODEF

Danyliw Standards Track [Page 112] RFC 7970 IODEF Version 2 November 2016

 implementations SHOULD periodically update their schema and MAY need
 to update their parsing algorithms to incorporate newly registered
 values.

4.4. Incompatibilities with v1

 The IODEF data model in this document makes a number of changes to
 [RFC5070].  These changes were largely additive -- classes and
 enumerated values were added.  However, some incompatibilities
 between [RFC5070] and this new specification were introduced.  These
 incompatibilities are as follows:
 o  The IODEF-Document@version attribute is set to "2.0".
 o  Attributes with enumerated values can now also be extended with
    IANA registries.
 o  All iodef:MLStringType classes use xml:lang.  IODEF-Document also
    uses xml:lang.
 o  The Service@ip_protocol attribute was renamed to @ip-protocol.
 o  The Node/NodeName class was removed in favor of representing
    domain names with Node/DomainData/Name class.  The Node/DataTime
    class was also removed, so that the Node/DomainData/
    DateDomainWasChecked class can represent the time at which the
    name-to-address resolution occurred.
 o  The Node/NodeRole class was moved to System/NodeRole.
 o  The Reference class is now defined by [RFC7495].
 o  The data previously represented in the Impact class is now in the
    SystemImpact and IncidentCategory classes.  The Impact class has
    been removed.
 o  The semantics of Counter@type are now represented in Counter@unit.
 o  The IODEF-Document@formatid attribute has been renamed to @format-
    id.
 o  The Incident/ReportTime class is no longer required.  However, the
    GenerationTime class is required.
 o  The Fax class was removed and is now represented by a generic
    Telephone class.

Danyliw Standards Track [Page 113] RFC 7970 IODEF Version 2 November 2016

 o  The Telephone, Email, and PostalAddress classes were redefined
    from improved internationalization.
 o  The "ipv6-net-mask" value was removed from the category attribute
    of Address.

5. Extending the IODEF

 In order to support the dynamic nature of security operations, the
 IODEF data model will need to continue to evolve.  This section
 discusses how new data elements can be incorporated into the IODEF.
 There is support to add additional enumerated values and new classes.
 Adding additional attributes to existing classes is not supported.
 These extension mechanisms are designed so that adding new data
 elements is possible without requiring modifications to this
 document.  Extensions can be implemented publicly or privately.  With
 proven value, well-documented extensions can be incorporated into
 future versions of the specification.

5.1. Extending the Enumerated Values of Attributes

 Additional enumerated values can be added to select attributes either
 through the use of specially marked attributes with the "ext-" prefix
 or through a set of corresponding IANA registries.  The former
 approach allows for the extension to remain private.  The latter
 approach is public.

5.1.1. Private Extension of Enumerated Values

 The data model supports adding new enumerated values to an attribute
 without public registration.  For each attribute that supports this
 extension technique, there is a corresponding attribute in the same
 element whose name is identical but with a prefix of "ext-".  This
 special attribute is referred to as the extension attribute.  The
 attribute being extended is referred to as an extensible attribute.
 For example, an extensible attribute named "foo" will have a
 corresponding extension attribute named "ext-foo".  An element may
 have many extensible attributes.
 In addition to a corresponding extension attribute, each extensible
 attribute has "ext-value" as one its possible enumerated values.
 Selection of this particular value in an extensible attribute signals
 that the extension attribute contains data.  Otherwise, this
 "ext-value" value has no meaning.

Danyliw Standards Track [Page 114] RFC 7970 IODEF Version 2 November 2016

 In order to add a new enumerated value to an extensible attribute,
 the value of this attribute MUST be set to "ext-value", and the new
 desired value MUST be set in the corresponding extension attribute.
 For example, extending the type attribute of the SystemImpact class
 would look as follows:
  <SystemImpact type="ext-value" ext-type="new-attack-type">
 A given extension attribute MUST NOT be set unless the corresponding
 extensible attribute has been set to "ext-value".

5.1.2. Public Extension of Enumerated Values

 The data model also supports publicly extending select enumerated
 attributes.  A new entry can be added by registering a new entry in
 the appropriate IANA registry.  Section 10.2 provides a mapping
 between the extensible attributes and their corresponding registry.
 Section 4.3 discusses the XML validation implications of this type of
 extension.  All extensible attributes that support private extensions
 also support public extensions.

5.2. Extending Classes

 Classes of the EXTENSION (iodef:ExtensionType) type can extend the
 data model.  They provide the ability to have new atomic or XML-
 encoded data elements in all of the top-level classes of the Incident
 class and in a few of the complex subordinate classes.  As there are
 multiple instances of the extensible classes in the data model, there
 is discretion on where to add a new data element.  It is RECOMMENDED
 that the extension be placed in the most closely related class to the
 new information.
 Extensions using the atomic data types (i.e., all values of the dtype
 attributes other than "xml") MUST:
 1.  Set the element content to the desired value, and
 2.  Set the dtype attribute to correspond to the data type of the
     element content.

Danyliw Standards Track [Page 115] RFC 7970 IODEF Version 2 November 2016

 The following guidelines exist for extensions using XML (i.e.,
 dtype="xml"):
 1.  The element content of the extensible class MUST be set to the
     desired value, and the dtype attribute MUST be set to "xml".
 2.  The extension schema MUST declare a separate namespace.  It is
     RECOMMENDED that these extensions have the prefix "iodef-".  This
     recommendation makes readability of the document easier by
     allowing the reader to infer which namespaces relate to IODEF by
     inspection.
 3.  It is RECOMMENDED that extension schemas follow the naming
     convention of the IODEF data model.  This too improves the
     readability of extended IODEF documents.  The names of all
     elements SHOULD be capitalized.  For elements with composed
     names, a capital letter SHOULD be used for each word.  Attribute
     names SHOULD be in lowercase.  Attributes with composed names
     SHOULD be separated by a hyphen.
 4.  Implementations that encounter an unrecognized element,
     attribute, or attribute value in a supported namespace SHOULD
     reject the document as a syntax error.
 5.  There are security and performance implications in requiring
     implementations to dynamically download schemas at runtime.
     Therefore, implementations MUST NOT download schemas at runtime
     unless the appropriate precautions are taken.  Implementations
     also need to contend with the potential of significant network
     and processing issues.
 6.  Some adopters of the IODEF may have private schema definitions
     that are not publicly available.  Thus, implementations may
     encounter IODEF documents with references to private schemas that
     may not be resolvable.  Hence, IODEF document recipients MUST be
     prepared for a schema definition in an IODEF document never to
     resolve.

Danyliw Standards Track [Page 116] RFC 7970 IODEF Version 2 November 2016

 The following schema and XML document excerpt provide a template for
 an extension schema and its use in the IODEF document.
 This example schema defines a namespace of "iodef-extension1" and a
 single element named "newdata".
   <xs:schema
      targetNamespace="iodef-extension1.xsd"
      xmlns:iodef-extension1="iodef-extension1.xsd"
      xmlns:xs="http://www.w3.org/2001/XMLSchema">
      attributeFormDefault="unqualified"
      elementFormDefault="qualified">
    <xs:import
         namespace="urn:ietf:params:xml:ns:iodef-2.0"
         schemaLocation=" urn:ietf:params:xml:schema:iodef-2.0"/>
      <xs:element name="newdata" type="xs:string" />
   </xs:schema>
 The following XML excerpt demonstrates the use of the above schema as
 an extension to the IODEF.
      <IODEF-Document
           version="2.00" lang="en-US"
           xmlns="urn:ietf:params:xml:ns:iodef-2.0"
           xmlns:iodef=" urn:ietf:params:xml:ns:iodef-2.0"
           xmlns:iodef-extension1="iodef-extension1.xsd"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="iodef-extension1.xsd">
          <Incident purpose="reporting">
          ...
            <AdditionalData dtype="xml" meaning="xml">
              <iodef-extension1:newdata>
               Field that could not be represented elsewhere
              </iodef-extension1:newdata>
            </AdditionalData>
          </Incident>
    </IODEF-Document>

5.3. Deconflicting Private Extensions

 To disambiguate which private extension is used in an IODEF document,
 the data model provides a means to identify the source of an
 extension.  Two attributes in the IODEF-Document class,
 private-enum-name and private-enum-id, are used to specify this
 attribution.  Only a single private extension can be identified in a
 given IODEF-Document.

Danyliw Standards Track [Page 117] RFC 7970 IODEF Version 2 November 2016

 If an implementor has a single private extension, then only the
 private-enum-name attribute needs to be specified.  Multiple distinct
 private extensions or versioning of a single extension can be
 attributed by also setting the corresponding private-num-id
 attribute.
 The following XML excerpt demonstrates the specification of a private
 extension from "example.com" with an identifier of "13".
      <IODEF-Document
           version="2.00" lang="en-US"
           private-enum-name="example.com"
           private-enum-id="13" ...>
          ...
    </IODEF-Document>
 If an unrecognized private extension is encountered in processing,
 the recipient MAY reject the entire document as a syntax error.

6. Internationalization Issues

 Internationalization and localization is of specific concern to the
 IODEF as it facilitates operational coordination with a diverse set
 of partners.  The IODEF implements internationalization by relying on
 XML constructs and through explicit design choices in the data model.
 Since the IODEF is implemented as an XML schema, it supports
 different character encodings, such as UTF-8 and UTF-16, that are
 possible with XML.  Additionally, each IODEF document MUST specify
 the language in which its content is encoded.  The language can be
 specified with the attribute "xml:lang" (per Section 2.12 of
 [W3C.XML]) in the top-level element (i.e., IODEF-Document) and lets
 all other elements inherit that definition.  All IODEF classes with a
 free-form text definition (i.e., all those defined with type
 iodef:MLStringType) can also specify a language different from the
 rest of the document.
 The data model supports multiple translations of free-form text.  All
 ML_STRING (iodef:MLStringType) classes have a one-to-many cardinality
 to their parent.  This allows the identical text translated into
 different languages to be encoded in different instances of the same
 class with a common parent.  This design also enables the creation of
 a single document containing all the translations.  The IODEF
 implementation SHOULD extract the appropriate language relevant to
 the recipient.

Danyliw Standards Track [Page 118] RFC 7970 IODEF Version 2 November 2016

 Related instances of a given iodef:MLStringType class that are
 translations of each other are identified by a common identifier set
 in the translation-id attribute.  The example below shows three
 instances of a Description class expressed in three different
 languages.  The relationship between these three instances of the
 Description class is conveyed by the common value of "1" in the
 translation-id attribute.
 <IODEF-Document version="2.00" xml:lang="en" ...>
   <Incident purpose="reporting">
     ...
     <Description translation-id="1"
                  xml:lang="en">English</Description>
     <Description translation-id="1"
                  xml:lang="de">Englisch</Description>
     <Description translation-id="1"
                  xml:lang="fr">Anglais</Description>
 The IODEF balances internationalization support with the need for
 interoperability.  While the IODEF supports different languages, the
 data model also relies heavily on standardized enumerated attributes
 that can crudely approximate the contents of the document.  With this
 approach, a CSIRT should be able to make some sense of an IODEF
 document it receives even if the free-form text data elements are
 written in a language unfamiliar to the recipient.

7. Examples

 This section provides examples of IODEF documents.  These examples do
 not represent the full capabilities of the data model or the only way
 to encode particular information.

7.1. Minimal Example

 A document containing only the mandatory elements and attributes.
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- Minimum IODEF document -->
 <IODEF-Document version="2.00" xml:lang="en"
    xmlns="urn:ietf:params:xml:ns:iodef-2.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation=
 "http://www.iana.org/assignments/xml-registry/schema/
 iodef-2.0.xsd">
   <Incident purpose="reporting" restriction="private">
     <IncidentID name="csirt.example.com">492382</IncidentID>
     <GenerationTime>2015-07-18T09:00:00-05:00</GenerationTime>
     <Contact type="organization" role="creator">

Danyliw Standards Track [Page 119] RFC 7970 IODEF Version 2 November 2016

       <Email>
         <EmailTo>contact@csirt.example.com</EmailTo>
       </Email>
     </Contact>
     <!-- Add more fields to make the document useful -->
   </Incident>
 </IODEF-Document>

7.2. Indicators from a Campaign

 An example of C2 domains from a given campaign.
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- A list of C2 domains associated with a campaign -->
 <IODEF-Document version="2.00" xml:lang="en"
    xmlns="urn:ietf:params:xml:ns:iodef-2.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation=
    "http://www.iana.org/assignments/xml-registry/schema/
     iodef-2.0.xsd">
   <Incident purpose="watch" restriction="green">
     <IncidentID name="csirt.example.com">897923</IncidentID>
       <RelatedActivity>
         <ThreatActor>
           <ThreatActorID>
           TA-12-AGGRESSIVE-BUTTERFLY
           </ThreatActorID>
           <Description>Aggressive Butterfly</Description>
         </ThreatActor>
         <Campaign>
           <CampaignID>C-2015-59405</CampaignID>
           <Description>Orange Giraffe</Description>
         </Campaign>
       </RelatedActivity>
       <GenerationTime>2015-10-02T11:18:00-05:00</GenerationTime>
       <Description>Summarizes the Indicators of Compromise
         for the Orange Giraffe campaign of the Aggressive
         Butterfly crime gang.
       </Description>
       <Assessment>
         <BusinessImpact type="breach-proprietary"/>
       </Assessment>
       <Contact type="organization" role="creator">
         <ContactName>CSIRT for example.com</ContactName>
         <Email>
           <EmailTo>contact@csirt.example.com</EmailTo>
         </Email>
       </Contact>

Danyliw Standards Track [Page 120] RFC 7970 IODEF Version 2 November 2016

       <IndicatorData>
         <Indicator>
           <IndicatorID name="csirt.example.com" version="1">
           G90823490
           </IndicatorID>
           <Description>C2 domains</Description>
           <StartTime>2014-12-02T11:18:00-05:00</StartTime>
           <Observable>
             <BulkObservable type="fqdn">
             <BulkObservableList>
               kj290023j09r34.example.com
               09ijk23jfj0k8.example.net
               klknjwfjiowjefr923.example.org
               oimireik79msd.example.org
             </BulkObservableList>
           </BulkObservable>
         </Observable>
       </Indicator>
     </IndicatorData>
   </Incident>
 </IODEF-Document>

8. The IODEF Data Model (XML Schema)

<?xml version="1.0"?>
<xs:schema xmlns="urn:ietf:params:xml:ns:iodef-2.0"
           xmlns:iodef="urn:ietf:params:xml:ns:iodef-2.0"
           xmlns:enum="urn:ietf:params:xml:ns:iodef-enum-1.0"
           xmlns:sci="urn:ietf:params:xml:ns:iodef-sci-1.0"
           xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
           targetNamespace="urn:ietf:params:xml:ns:iodef-2.0"
           elementFormDefault="qualified"
           attributeFormDefault="unqualified">
  <xs:import namespace="http://www.w3.org/2000/09/xmldsig#"
             schemaLocation="http://www.w3.org/TR/2002/
REC-xmldsig-core-20020212/xmldsig-core-schema.xsd"/>
  <xs:import namespace="urn:ietf:params:xml:ns:iodef-enum-1.0"
             schemaLocation="http://www.iana.org/assignments/
xml-registry/schema/iodef-enum-1.0.xsd"/>
  <xs:import namespace="urn:ietf:params:xml:ns:iodef-sci-1.0"
             schemaLocation="http://www.iana.org/assignments/
xml-registry/schema/iodef-sci-1.0.xsd"/>
  <xs:import namespace="http://www.w3.org/XML/1998/namespace"
             schemaLocation="http://www.w3c.org/2001/xml.xsd"/>
  <xs:annotation>
    <xs:documentation>
       Incident Object Description Exchange Format v2.0

Danyliw Standards Track [Page 121] RFC 7970 IODEF Version 2 November 2016

    </xs:documentation>
  </xs:annotation>
  <!--
   ===================================================================
   == IODEF-Document class                                          ==
   ===================================================================
  -->
  <xs:element name="IODEF-Document">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Incident" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="version" type="xs:string" fixed="2.00"/>
      <xs:attribute ref="xml:lang"/>
      <xs:attribute name="format-id" type="xs:string" use="optional"/>
      <xs:attribute name="private-enum-name"
                    type="xs:string" use="optional"/>
      <xs:attribute name="private-enum-id"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   == Incident class                                                ==
   ===================================================================
  -->
  <xs:element name="Incident">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:IncidentID"/>
        <xs:element ref="iodef:AlternativeID" minOccurs="0"/>
        <xs:element ref="iodef:RelatedActivity"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:DetectTime" minOccurs="0"/>
        <xs:element ref="iodef:StartTime" minOccurs="0"/>
        <xs:element ref="iodef:EndTime" minOccurs="0"/>
        <xs:element ref="iodef:RecoveryTime" minOccurs="0"/>
        <xs:element ref="iodef:ReportTime" minOccurs="0"/>
        <xs:element ref="iodef:GenerationTime"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Discovery"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Assessment"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Method"

Danyliw Standards Track [Page 122] RFC 7970 IODEF Version 2 November 2016

                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Contact" maxOccurs="unbounded"/>
        <xs:element ref="iodef:EventData"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:IndicatorData" minOccurs="0"/>
        <xs:element ref="iodef:History" minOccurs="0"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="purpose"
                    type="incident-purpose-type" use="required"/>
      <xs:attribute name="ext-purpose"
                    type="xs:string" use="optional"/>
      <xs:attribute name="status" type="incident-status-type"/>
      <xs:attribute name="ext-status"
                    type="xs:string" use="optional"/>
      <xs:attribute ref="xml:lang"/>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" default="private"
                    use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="incident-purpose-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="traceback"/>
      <xs:enumeration value="mitigation"/>
      <xs:enumeration value="reporting"/>
      <xs:enumeration value="watch"/>
      <xs:enumeration value="other"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="incident-status-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="new"/>
      <xs:enumeration value="in-progress"/>
      <xs:enumeration value="forwarded"/>
      <xs:enumeration value="resolved"/>
      <xs:enumeration value="future"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>

Danyliw Standards Track [Page 123] RFC 7970 IODEF Version 2 November 2016

  <!--
   ===================================================================
   ==  IncidentID class                                             ==
   ===================================================================
  -->
  <xs:element name="IncidentID" type="iodef:IncidentIDType"/>
  <xs:complexType name="IncidentIDType">
    <xs:simpleContent>
      <xs:extension base="xs:string">
        <xs:attribute name="name" type="xs:string" use="required"/>
        <xs:attribute name="instance"
                      type="xs:string" use="optional"/>
        <xs:attribute name="restriction"
                      type="iodef:restriction-type" use="optional"/>
        <xs:attribute name="ext-restriction"
                      type="xs:string" use="optional"/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>
  <!--
   ==================================================================
   ==  AlternativeID class                                         ==
   ==================================================================
  -->
  <xs:element name="AlternativeID">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:IncidentID" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   ==  RelatedActivity class                                        ==
   ===================================================================
  -->
  <xs:element name="RelatedActivity">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:IncidentID"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:URL"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:ThreatActor"

Danyliw Standards Track [Page 124] RFC 7970 IODEF Version 2 November 2016

                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Campaign"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:IndicatorID"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Confidence" minOccurs="0"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="ThreatActor">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:ThreatActorID"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:URL" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="ThreatActorID" type="xs:string"/>
  <xs:element name="Campaign">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:CampaignID"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:URL"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"

Danyliw Standards Track [Page 125] RFC 7970 IODEF Version 2 November 2016

                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="CampaignID" type="xs:string"/>
  <!--
   ===================================================================
   ==   Contact class                                               ==
   ===================================================================
  -->
  <xs:element name="Contact">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:ContactName"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:ContactTitle"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:RegistryHandle"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:PostalAddress"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Email"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Telephone"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Timezone" minOccurs="0"/>
        <xs:element ref="iodef:Contact"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="role"
                    type="contact-role-type" use="required"/>
      <xs:attribute name="ext-role"
                    type="xs:string" use="optional"/>
      <xs:attribute name="type"
                    type="contact-type-type" use="required"/>
      <xs:attribute name="ext-type"
                    type="xs:string" use="optional"/>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>

Danyliw Standards Track [Page 126] RFC 7970 IODEF Version 2 November 2016

  <xs:simpleType name="contact-role-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="creator"/>
      <xs:enumeration value="reporter"/>
      <xs:enumeration value="admin"/>
      <xs:enumeration value="tech"/>
      <xs:enumeration value="provider"/>
      <xs:enumeration value="user"/>
      <xs:enumeration value="billing"/>
      <xs:enumeration value="legal"/>
      <xs:enumeration value="abuse"/>
      <xs:enumeration value="irt"/>
      <xs:enumeration value="cc"/>
      <xs:enumeration value="cc-irt"/>
      <xs:enumeration value="leo"/>
      <xs:enumeration value="vendor"/>
      <xs:enumeration value="vendor-services"/>
      <xs:enumeration value="victim"/>
      <xs:enumeration value="victim-notified"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="contact-type-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="person"/>
      <xs:enumeration value="organization"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="ContactName" type="iodef:MLStringType"/>
  <xs:element name="ContactTitle" type="iodef:MLStringType"/>
  <xs:element name="RegistryHandle">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="registry"
                        type="registryhandle-registry-type"/>
          <xs:attribute name="ext-registry"
                        type="xs:string" use="optional"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="registryhandle-registry-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="internic"/>
      <xs:enumeration value="apnic"/>
      <xs:enumeration value="arin"/>

Danyliw Standards Track [Page 127] RFC 7970 IODEF Version 2 November 2016

      <xs:enumeration value="lacnic"/>
      <xs:enumeration value="ripe"/>
      <xs:enumeration value="afrinic"/>
      <xs:enumeration value="local"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="PostalAddress">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:PAddress"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="type"
                    type="postaladdress-type-type" use="optional"/>
      <xs:attribute name="ext-type" type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="PAddress" type="iodef:MLStringType"/>
  <xs:simpleType name="postaladdress-type-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="street"/>
      <xs:enumeration value="mailing"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="Telephone">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:TelephoneNumber"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="type"
                    type="telephone-type-type" use="optional"/>
      <xs:attribute name="ext-type" type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="TelephoneNumber" type="xs:string"/>
  <xs:simpleType name="telephone-type-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="wired"/>
      <xs:enumeration value="mobile"/>
      <xs:enumeration value="fax"/>
      <xs:enumeration value="hotline"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>

Danyliw Standards Track [Page 128] RFC 7970 IODEF Version 2 November 2016

  </xs:simpleType>
  <xs:element name="Email">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:EmailTo"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="type"
                    type="email-type-type" use="optional"/>
      <xs:attribute name="ext-type" type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="email-type-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="direct"/>
      <xs:enumeration value="hotline"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <!--
   ===================================================================
   ==  Time-based classes                                           ==
   ===================================================================
  -->
  <xs:element name="DateTime" type="xs:dateTime"/>
  <xs:element name="ReportTime" type="xs:dateTime"/>
  <xs:element name="DetectTime" type="xs:dateTime"/>
  <xs:element name="StartTime" type="xs:dateTime"/>
  <xs:element name="EndTime" type="xs:dateTime"/>
  <xs:element name="RecoveryTime" type="xs:dateTime"/>
  <xs:element name="GenerationTime" type="xs:dateTime"/>
  <xs:element name="Timezone" type="iodef:TimezoneType"/>
  <!--
   ===================================================================
   ==  History class                                                ==
   ===================================================================
  -->
  <xs:element name="History">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:HistoryItem" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>

Danyliw Standards Track [Page 129] RFC 7970 IODEF Version 2 November 2016

  </xs:element>
  <xs:element name="HistoryItem">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:DateTime"/>
        <xs:element ref="iodef:IncidentID" minOccurs="0"/>
        <xs:element ref="iodef:Contact" minOccurs="0"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:DefinedCOA"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="action"
                    type="iodef:action-type" use="required"/>
      <xs:attribute name="ext-action"
                    type="xs:string" use="optional"/>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="DefinedCOA" type="xs:string"/>
  <!--
   ===================================================================
   ==  Expectation class                                            ==
   ===================================================================
  -->
  <xs:element name="Expectation">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:DefinedCOA"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:StartTime" minOccurs="0"/>
        <xs:element ref="iodef:EndTime" minOccurs="0"/>
        <xs:element ref="iodef:Contact" minOccurs="0"/>
      </xs:sequence>
      <xs:attribute name="action"
                    type="iodef:action-type" default="other"/>
      <xs:attribute name="ext-action"
                    type="xs:string" use="optional"/>
      <xs:attribute name="severity" type="iodef:severity-type"/>
      <xs:attribute name="restriction"

Danyliw Standards Track [Page 130] RFC 7970 IODEF Version 2 November 2016

                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   ==  Discovery class                                              ==
   ===================================================================
  -->
  <xs:element name="Discovery">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Contact"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:DetectionPattern"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="source"
                    type="discovery-source-type" use="optional"
                    default="unknown"/>
      <xs:attribute name="ext-source"
                    type="xs:string" use="optional"/>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="discovery-source-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="nidps"/>
      <xs:enumeration value="hips"/>
      <xs:enumeration value="siem"/>
      <xs:enumeration value="av"/>
      <xs:enumeration value="third-party-monitoring"/>
      <xs:enumeration value="incident"/>
      <xs:enumeration value="os-log"/>
      <xs:enumeration value="application-log"/>
      <xs:enumeration value="device-log"/>
      <xs:enumeration value="network-flow"/>
      <xs:enumeration value="passive-dns"/>
      <xs:enumeration value="investigation"/>
      <xs:enumeration value="audit"/>
      <xs:enumeration value="internal-notification"/>

Danyliw Standards Track [Page 131] RFC 7970 IODEF Version 2 November 2016

      <xs:enumeration value="external-notification"/>
      <xs:enumeration value="leo"/>
      <xs:enumeration value="partner"/>
      <xs:enumeration value="actor"/>
      <xs:enumeration value="unknown"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="DetectionPattern">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Application"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element name="DetectionConfiguration"
                    type="xs:string"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   ==  Method class                                                 ==
   ===================================================================
  -->
  <xs:element name="Method">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Reference"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="sci:AttackPattern"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="sci:Vulnerability"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="sci:Weakness"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>

Danyliw Standards Track [Page 132] RFC 7970 IODEF Version 2 November 2016

      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   ==  Reference class                                              ==
   ===================================================================
  -->
  <xs:element name="Reference">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="enum:ReferenceName" minOccurs="0"/>
        <xs:element ref="iodef:URL"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   ==  Assessment class                                             ==
   ===================================================================
  -->
  <xs:element name="Assessment">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:IncidentCategory"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:choice maxOccurs="unbounded">
          <xs:element ref="iodef:SystemImpact"/>
          <xs:element ref="iodef:BusinessImpact"/>
          <xs:element ref="iodef:TimeImpact"/>
          <xs:element ref="iodef:MonetaryImpact"/>
          <xs:element ref="iodef:IntendedImpact"/>
        </xs:choice>
        <xs:element ref="iodef:Counter"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:MitigatingFactor"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Cause"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Confidence" minOccurs="0"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>

Danyliw Standards Track [Page 133] RFC 7970 IODEF Version 2 November 2016

      <xs:attribute name="occurrence">
        <xs:simpleType>
          <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="actual"/>
            <xs:enumeration value="potential"/>
          </xs:restriction>
        </xs:simpleType>
      </xs:attribute>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="IncidentCategory" type="iodef:MLStringType"/>
  <xs:element name="BusinessImpact" type="iodef:BusinessImpactType"/>
  <xs:element name="IntendedImpact" type="iodef:BusinessImpactType"/>
  <xs:element name="MitigatingFactor" type="iodef:MLStringType"/>
  <xs:element name="Cause" type="iodef:MLStringType"/>
  <xs:element name="SystemImpact">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="severity"
                    type="iodef:severity-type" use="optional"/>
      <xs:attribute name="completion"
                    type="iodef:systemimpact-completion-type"
                    use="optional"/>
      <xs:attribute name="type"
                    type="systemimpact-type-type"
                    use="optional" default="unknown"/>
      <xs:attribute name="ext-type" type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="systemimpact-completion-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="failed"/>
      <xs:enumeration value="succeeded"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="systemimpact-type-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="takeover-account"/>
      <xs:enumeration value="takeover-service"/>
      <xs:enumeration value="takeover-system"/>

Danyliw Standards Track [Page 134] RFC 7970 IODEF Version 2 November 2016

      <xs:enumeration value="cps-manipulation"/>
      <xs:enumeration value="cps-damage"/>
      <xs:enumeration value="availability-data"/>
      <xs:enumeration value="availability-account"/>
      <xs:enumeration value="availability-service"/>
      <xs:enumeration value="availability-system"/>
      <xs:enumeration value="damaged-system"/>
      <xs:enumeration value="damaged-data"/>
      <xs:enumeration value="breach-proprietary"/>
      <xs:enumeration value="breach-privacy"/>
      <xs:enumeration value="breach-credential"/>
      <xs:enumeration value="breach-configuration"/>
      <xs:enumeration value="integrity-data"/>
      <xs:enumeration value="integrity-configuration"/>
      <xs:enumeration value="integrity-hardware"/>
      <xs:enumeration value="traffic-redirection"/>
      <xs:enumeration value="monitoring-traffic"/>
      <xs:enumeration value="monitoring-host"/>
      <xs:enumeration value="policy"/>
      <xs:enumeration value="unknown"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:complexType name="BusinessImpactType">
    <xs:sequence>
      <xs:element ref="iodef:Description"
                  minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="severity"
                  type="businessimpact-severity-type" use="optional"/>
    <xs:attribute name="ext-severity"
                  type="xs:string" use="optional"/>
    <xs:attribute name="type"
                  type="businessimpact-type-type"
                  use="optional" default="unknown"/>
    <xs:attribute name="ext-type" type="xs:string" use="optional"/>
  </xs:complexType>
  <xs:simpleType name="businessimpact-severity-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="none"/>
      <xs:enumeration value="low"/>
      <xs:enumeration value="medium"/>
      <xs:enumeration value="high"/>
      <xs:enumeration value="unknown"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="businessimpact-type-type">

Danyliw Standards Track [Page 135] RFC 7970 IODEF Version 2 November 2016

    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="breach-proprietary"/>
      <xs:enumeration value="breach-privacy"/>
      <xs:enumeration value="breach-credential"/>
      <xs:enumeration value="loss-of-integrity"/>
      <xs:enumeration value="loss-of-service"/>
      <xs:enumeration value="theft-financial"/>
      <xs:enumeration value="theft-service"/>
      <xs:enumeration value="degraded-reputation"/>
      <xs:enumeration value="asset-damage"/>
      <xs:enumeration value="asset-manipulation"/>
      <xs:enumeration value="legal"/>
      <xs:enumeration value="extortion"/>
      <xs:enumeration value="unknown"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="TimeImpact">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="iodef:PositiveFloatType">
          <xs:attribute name="severity" type="iodef:severity-type"/>
          <xs:attribute name="metric"
                        type="timeimpact-metric-type" use="required"/>
          <xs:attribute name="ext-metric"
                        type="xs:string" use="optional"/>
          <xs:attribute name="duration" type="iodef:duration-type"/>
          <xs:attribute name="ext-duration"
                        type="xs:string" use="optional"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="timeimpact-metric-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="labor"/>
      <xs:enumeration value="elapsed"/>
      <xs:enumeration value="downtime"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="MonetaryImpact">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="iodef:PositiveFloatType">
          <xs:attribute name="severity" type="iodef:severity-type"/>
          <xs:attribute name="currency" type="xs:string"/>
        </xs:extension>

Danyliw Standards Track [Page 136] RFC 7970 IODEF Version 2 November 2016

      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="Confidence">
    <xs:complexType>
      <xs:attribute name="rating"
                    type="confidence-rating-type" use="required"/>
      <xs:attribute name="ext-rating"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="confidence-rating-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="low"/>
      <xs:enumeration value="medium"/>
      <xs:enumeration value="high"/>
      <xs:enumeration value="numeric"/>
      <xs:enumeration value="unknown"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <!--
   ===================================================================
   == EventData class                                               ==
   ===================================================================
  -->
  <xs:element name="EventData">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:DetectTime" minOccurs="0"/>
        <xs:element ref="iodef:StartTime" minOccurs="0"/>
        <xs:element ref="iodef:EndTime" minOccurs="0"/>
        <xs:element ref="iodef:RecoveryTime" minOccurs="0"/>
        <xs:element ref="iodef:ReportTime" minOccurs="0"/>
        <xs:element ref="iodef:Contact"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Discovery"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Assessment" minOccurs="0"/>
        <xs:element ref="iodef:Method"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Flow"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Expectation"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Record" minOccurs="0"/>

Danyliw Standards Track [Page 137] RFC 7970 IODEF Version 2 November 2016

        <xs:element ref="iodef:EventData"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   ==  Flow class                                                   ==
   ===================================================================
  -->
  <xs:element name="Flow">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:System" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   ==  System class                                                 ==
   ===================================================================
  -->
  <xs:element name="System">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Node"/>
        <xs:element ref="iodef:NodeRole"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Service"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:OperatingSystem"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Counter"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element name="AssetID"
                    type="xs:string"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>

Danyliw Standards Track [Page 138] RFC 7970 IODEF Version 2 November 2016

      </xs:sequence>
      <xs:attribute name="category" type="system-category-type"/>
      <xs:attribute name="ext-category"
                    type="xs:string" use="optional"/>
      <xs:attribute name="interface" type="xs:string"/>
      <xs:attribute name="spoofed"
                    type="yes-no-unknown-type" default="unknown"/>
      <xs:attribute name="virtual"
                    type="yes-no-unknown-type" use="optional"
                    default="unknown"/>
      <xs:attribute name="ownership" type="system-ownership-type"
                    use="optional"/>
      <xs:attribute name="ext-ownership"
                    type="xs:string" use="optional"/>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="OperatingSystem" type="iodef:SoftwareType"/>
  <xs:simpleType name="system-category-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="source"/>
      <xs:enumeration value="target"/>
      <xs:enumeration value="intermediate"/>
      <xs:enumeration value="sensor"/>
      <xs:enumeration value="infrastructure"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="system-ownership-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="organization"/>
      <xs:enumeration value="personal"/>
      <xs:enumeration value="partner"/>
      <xs:enumeration value="customer"/>
      <xs:enumeration value="no-relationship"/>
      <xs:enumeration value="unknown"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <!--
   ==================================================================
   == Node class                                                   ==
   ==================================================================
  -->

Danyliw Standards Track [Page 139] RFC 7970 IODEF Version 2 November 2016

  <xs:element name="Node">
    <xs:complexType>
      <xs:sequence>
        <xs:choice maxOccurs="unbounded">
          <xs:element ref="iodef:DomainData"
                      minOccurs="0" maxOccurs="unbounded"/>
          <xs:element ref="iodef:Address"
                      minOccurs="0" maxOccurs="unbounded"/>
        </xs:choice>
        <xs:element ref="iodef:PostalAddress" minOccurs="0"/>
        <xs:element ref="iodef:Location"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Counter"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="Address">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="category"
                        type="address-category-type"
                        default="ipv6-addr"/>
          <xs:attribute name="ext-category"
                        type="xs:string" use="optional"/>
          <xs:attribute name="vlan-name" type="xs:string"/>
          <xs:attribute name="vlan-num" type="xs:integer"/>
          <xs:attribute name="observable-id"
                        type="xs:ID" use="optional"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="address-category-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="asn"/>
      <xs:enumeration value="atm"/>
      <xs:enumeration value="e-mail"/>
      <xs:enumeration value="mac"/>
      <xs:enumeration value="ipv4-addr"/>
      <xs:enumeration value="ipv4-net"/>
      <xs:enumeration value="ipv4-net-masked"/>
      <xs:enumeration value="ipv4-net-mask"/>
      <xs:enumeration value="ipv6-addr"/>
      <xs:enumeration value="ipv6-net"/>
      <xs:enumeration value="ipv6-net-masked"/>
      <xs:enumeration value="site-uri"/>

Danyliw Standards Track [Page 140] RFC 7970 IODEF Version 2 November 2016

      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="Location" type="iodef:MLStringType"/>
  <xs:element name="NodeRole">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="category"
                    type="noderole-category-type" use="required"/>
      <xs:attribute name="ext-category"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="noderole-category-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="client"/>
      <xs:enumeration value="client-enterprise"/>
      <xs:enumeration value="client-partner"/>
      <xs:enumeration value="client-remote"/>
      <xs:enumeration value="client-kiosk"/>
      <xs:enumeration value="client-mobile"/>
      <xs:enumeration value="server-internal"/>
      <xs:enumeration value="server-public"/>
      <xs:enumeration value="www"/>
      <xs:enumeration value="mail"/>
      <xs:enumeration value="webmail"/>
      <xs:enumeration value="messaging"/>
      <xs:enumeration value="streaming"/>
      <xs:enumeration value="voice"/>
      <xs:enumeration value="file"/>
      <xs:enumeration value="ftp"/>
      <xs:enumeration value="p2p"/>
      <xs:enumeration value="name"/>
      <xs:enumeration value="directory"/>
      <xs:enumeration value="credential"/>
      <xs:enumeration value="print"/>
      <xs:enumeration value="application"/>
      <xs:enumeration value="database"/>
      <xs:enumeration value="backup"/>
      <xs:enumeration value="dhcp"/>
      <xs:enumeration value="assessment"/>
      <xs:enumeration value="source-control"/>
      <xs:enumeration value="config-management"/>
      <xs:enumeration value="monitoring"/>
      <xs:enumeration value="infra"/>

Danyliw Standards Track [Page 141] RFC 7970 IODEF Version 2 November 2016

      <xs:enumeration value="infra-firewall"/>
      <xs:enumeration value="infra-router"/>
      <xs:enumeration value="infra-switch"/>
      <xs:enumeration value="camera"/>
      <xs:enumeration value="proxy"/>
      <xs:enumeration value="remote-access"/>
      <xs:enumeration value="log"/>
      <xs:enumeration value="virtualization"/>
      <xs:enumeration value="pos"/>
      <xs:enumeration value="scada"/>
      <xs:enumeration value="scada-supervisory"/>
      <xs:enumeration value="sinkhole"/>
      <xs:enumeration value="honeypot"/>
      <xs:enumeration value="anonymization"/>
      <xs:enumeration value="c2-server"/>
      <xs:enumeration value="malware-distribution"/>
      <xs:enumeration value="drop-server"/>
      <xs:enumeration value="hop-point"/>
      <xs:enumeration value="reflector"/>
      <xs:enumeration value="phishing-site"/>
      <xs:enumeration value="spear-phishing-site"/>
      <xs:enumeration value="recruiting-site"/>
      <xs:enumeration value="fraudulent-site"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <!--
   ===================================================================
   ==  Service class                                                ==
   ===================================================================
  -->
  <xs:element name="Service">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:ServiceName" minOccurs="0"/>
        <xs:element ref="iodef:Port" minOccurs="0"/>
        <xs:element ref="iodef:Portlist" minOccurs="0"/>
        <xs:element ref="iodef:ProtoType" minOccurs="0"/>
        <xs:element ref="iodef:ProtoCode" minOccurs="0"/>
        <xs:element ref="iodef:ProtoField" minOccurs="0"/>
        <xs:element ref="iodef:ApplicationHeader" minOccurs="0"/>
        <xs:element ref="iodef:EmailData" minOccurs="0"/>
        <xs:element ref="iodef:Application" minOccurs="0"/>
      </xs:sequence>
      <xs:attribute name="ip-protocol"
                    type="xs:integer" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>

Danyliw Standards Track [Page 142] RFC 7970 IODEF Version 2 November 2016

  </xs:element>
  <xs:element name="Port" type="xs:integer"/>
  <xs:element name="Portlist" type="iodef:PortlistType"/>
  <xs:element name="ProtoType" type="xs:integer"/>
  <xs:element name="ProtoCode" type="xs:integer"/>
  <xs:element name="ProtoField" type="xs:integer"/>
  <xs:element name="ApplicationHeader">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:ApplicationHeaderField"
                    maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="ApplicationHeaderField"
              type="iodef:ExtensionType"/>
  <xs:element name="ServiceName">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:IANAService"
                    minOccurs="0"/>
        <xs:element ref="iodef:URL"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="IANAService" type="xs:string"/>
  <xs:element name="Application" type="iodef:SoftwareType"/>
  <!--
   ===================================================================
   ==  Counter class                                                ==
   ===================================================================
  -->
  <xs:element name="Counter">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:float">
          <xs:attribute name="type"
                        type="counter-type-type" use="required"/>
          <xs:attribute name="ext-type"
                        type="xs:string" use="optional"/>
          <xs:attribute name="unit"
                        type="counter-unit-type" use="required"/>
          <xs:attribute name="ext-unit"
                        type="xs:string" use="optional"/>
          <xs:attribute name="meaning"

Danyliw Standards Track [Page 143] RFC 7970 IODEF Version 2 November 2016

                        type="xs:string" use="optional"/>
          <xs:attribute name="duration" type="iodef:duration-type"/>
          <xs:attribute name="ext-duration"
                        type="xs:string" use="optional"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="counter-type-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="counter"/>
      <xs:enumeration value="rate"/>
      <xs:enumeration value="average"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="counter-unit-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="byte"/>
      <xs:enumeration value="mbit"/>
      <xs:enumeration value="packet"/>
      <xs:enumeration value="flow"/>
      <xs:enumeration value="session"/>
      <xs:enumeration value="event"/>
      <xs:enumeration value="alert"/>
      <xs:enumeration value="message"/>
      <xs:enumeration value="host"/>
      <xs:enumeration value="site"/>
      <xs:enumeration value="organization"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <!--
   ===================================================================
   ==  EmailData class                                              ==
   ===================================================================
  -->
  <xs:element name="EmailData">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:EmailTo"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:EmailFrom" minOccurs="0"/>
        <xs:element ref="iodef:EmailSubject" minOccurs="0"/>
        <xs:element ref="iodef:EmailX-Mailer" minOccurs="0"/>
        <xs:element ref="iodef:EmailHeaderField"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:EmailHeaders" minOccurs="0"/>

Danyliw Standards Track [Page 144] RFC 7970 IODEF Version 2 November 2016

        <xs:element ref="iodef:EmailBody" minOccurs="0"/>
        <xs:element ref="iodef:EmailMessage" minOccurs="0"/>
        <xs:element ref="iodef:HashData"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="SignatureData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="EmailTo" type="xs:string"/>
  <xs:element name="EmailFrom" type="xs:string"/>
  <xs:element name="EmailSubject" type="xs:string"/>
  <xs:element name="EmailX-Mailer" type="xs:string"/>
  <xs:element name="EmailHeaderField" type="iodef:ExtensionType"/>
  <xs:element name="EmailHeaders" type="xs:string"/>
  <xs:element name="EmailBody" type="xs:string"/>
  <xs:element name="EmailMessage" type="xs:string"/>
  <!--
   ===================================================================
   ==   DomainData class                                            ==
   ===================================================================
  -->
  <xs:element name="DomainData">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Name"/>
        <xs:element ref="iodef:DateDomainWasChecked"
                    minOccurs="0"/>
        <xs:element ref="iodef:RegistrationDate"
                    minOccurs="0"/>
        <xs:element ref="iodef:ExpirationDate"
                    minOccurs="0"/>
        <xs:element ref="iodef:RelatedDNS"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Nameservers"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:DomainContacts"
                    minOccurs="0"/>
      </xs:sequence>
      <xs:attribute name="system-status"
                    type="domaindata-system-status-type"/>
      <xs:attribute name="ext-system-status"
                    type="xs:string" use="optional"/>
      <xs:attribute name="domain-status"
                    type="domaindata-domain-status-type"/>
      <xs:attribute name="ext-domain-status"
                    type="xs:string" use="optional"/>

Danyliw Standards Track [Page 145] RFC 7970 IODEF Version 2 November 2016

      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="Name" type="xs:string"/>
  <xs:element name="DateDomainWasChecked" type="xs:dateTime"/>
  <xs:element name="RegistrationDate" type="xs:dateTime"/>
  <xs:element name="ExpirationDate" type="xs:dateTime"/>
  <xs:simpleType name="domaindata-system-status-type">
    <xs:restriction base="xs:string">
      <xs:enumeration value="spoofed"/>
      <xs:enumeration value="fraudulent"/>
      <xs:enumeration value="innocent-hacked"/>
      <xs:enumeration value="innocent-hijacked"/>
      <xs:enumeration value="unknown"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="domaindata-domain-status-type">
    <xs:restriction base="xs:string">
      <xs:enumeration value="reservedDelegation"/>
      <xs:enumeration value="assignedAndActive"/>
      <xs:enumeration value="assignedAndInactive"/>
      <xs:enumeration value="assignedAndOnHold"/>
      <xs:enumeration value="revoked"/>
      <xs:enumeration value="transferPending"/>
      <xs:enumeration value="registryLock"/>
      <xs:enumeration value="registrarLock"/>
      <xs:enumeration value="other"/>
      <xs:enumeration value="unknown"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="RelatedDNS" type="iodef:ExtensionType"/>
  <xs:element name="Nameservers">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Server"/>
        <xs:element ref="iodef:Address" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="Server" type="xs:string"/>
  <xs:element name="DomainContacts">
    <xs:complexType>
      <xs:choice>
        <xs:element ref="iodef:SameDomainContact"/>
        <xs:element ref="iodef:Contact"
                    minOccurs="1" maxOccurs="unbounded"/>

Danyliw Standards Track [Page 146] RFC 7970 IODEF Version 2 November 2016

      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:element name="SameDomainContact" type="xs:string"/>
  <!--
   ===================================================================
   ==  Record class                                                 ==
   ===================================================================
  -->
  <xs:element name="Record">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:RecordData" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="RecordData">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:DateTime" minOccurs="0"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Application" minOccurs="0"/>
        <xs:element ref="iodef:RecordPattern"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:RecordItem"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:URL"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:FileData"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:WindowsRegistryKeysModified"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:CertificateData"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>

Danyliw Standards Track [Page 147] RFC 7970 IODEF Version 2 November 2016

  </xs:element>
  <xs:element name="RecordPattern">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:string">
          <xs:attribute name="type"
                        type="recordpattern-type-type"
                        use="required"/>
          <xs:attribute name="ext-type"
                        type="xs:string" use="optional"/>
          <xs:attribute name="offset"
                        type="xs:integer" use="optional"/>
          <xs:attribute name="offsetunit"
                        type="recordpattern-offsetunit-type"
                        use="optional" default="line"/>
          <xs:attribute name="ext-offsetunit"
                        type="xs:string" use="optional"/>
          <xs:attribute name="instance"
                        type="xs:integer" use="optional"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="recordpattern-type-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="regex"/>
      <xs:enumeration value="binary"/>
      <xs:enumeration value="xpath"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="recordpattern-offsetunit-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="line"/>
      <xs:enumeration value="byte"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="RecordItem" type="iodef:ExtensionType"/>
  <!--
   ===================================================================
   ==  WindowsRegistryKeysModified class                            ==
   ===================================================================
  -->
  <xs:element name="WindowsRegistryKeysModified">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Key" maxOccurs="unbounded"/>

Danyliw Standards Track [Page 148] RFC 7970 IODEF Version 2 November 2016

      </xs:sequence>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="Key">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:KeyName"/>
        <xs:element ref="iodef:Value" minOccurs="0"/>
      </xs:sequence>
      <xs:attribute name="registryaction"
                    type="key-registryaction-type"/>
      <xs:attribute name="ext-registryaction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="KeyName" type="xs:string"/>
  <xs:element name="Value" type="xs:string"/>
  <xs:simpleType name="key-registryaction-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="add-key"/>
      <xs:enumeration value="add-value"/>
      <xs:enumeration value="delete-key"/>
      <xs:enumeration value="delete-value"/>
      <xs:enumeration value="modify-key"/>
      <xs:enumeration value="modify-value"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <!--
  ====================================================================
  ==  FileData class                                                ==
  ====================================================================
  -->
  <xs:element name="FileData">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:File"
                    minOccurs="1" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>

Danyliw Standards Track [Page 149] RFC 7970 IODEF Version 2 November 2016

  <xs:element name="File">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:FileName" minOccurs="0"/>
        <xs:element ref="iodef:FileSize" minOccurs="0"/>
        <xs:element ref="FileType" minOccurs="0"/>
        <xs:element ref="iodef:URL"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:HashData" minOccurs="0"/>
        <xs:element ref="iodef:SignatureData" minOccurs="0"/>
        <xs:element ref="iodef:AssociatedSoftware" minOccurs="0"/>
        <xs:element ref="iodef:FileProperties"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="FileName" type="xs:string"/>
  <xs:element name="FileSize" type="xs:integer"/>
  <xs:element name="FileType" type="xs:string"/>
  <xs:element name="AssociatedSoftware" type="iodef:SoftwareType"/>
  <xs:element name="FileProperties" type="iodef:ExtensionType"/>
  <!--
  ====================================================================
  ==  HashData class                                                ==
  ====================================================================
  -->
  <xs:element name="HashData">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:HashTargetID" minOccurs="0"/>
        <xs:element ref="iodef:Hash"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:FuzzyHash"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="scope"
                    type="hashdata-scope-type" use="required"/>
      <xs:attribute name="ext-scope" type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="HashTargetID" type="xs:string"/>
  <xs:simpleType name="hashdata-scope-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="file-contents"/>
      <xs:enumeration value="file-pe-section"/>
      <xs:enumeration value="file-pe-iat"/>
      <xs:enumeration value="file-pe-resource"/>

Danyliw Standards Track [Page 150] RFC 7970 IODEF Version 2 November 2016

      <xs:enumeration value="file-pdf-object"/>
      <xs:enumeration value="email-hash"/>
      <xs:enumeration value="email-headers-hash"/>
      <xs:enumeration value="email-body-hash"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="Hash">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="ds:DigestMethod"/>
        <xs:element ref="ds:DigestValue"/>
        <xs:element ref="ds:CanonicalizationMethod"
                    minOccurs="0"/>
        <xs:element ref="iodef:Application" minOccurs="0"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="FuzzyHash">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:FuzzyHashValue"
                    maxOccurs="unbounded"/>
        <xs:element ref="iodef:Application" minOccurs="0"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="FuzzyHashValue" type="iodef:ExtensionType"/>
  <!--
   ===================================================================
   ==  SignatureData class                                          ==
   ===================================================================
  -->
  <xs:element name="SignatureData">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="ds:Signature" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   ==  CertificateData class                                        ==
   ===================================================================
  -->
  <xs:element name="CertificateData">

Danyliw Standards Track [Page 151] RFC 7970 IODEF Version 2 November 2016

    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Certificate" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="Certificate">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="ds:X509Data"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
    </xs:complexType>
  </xs:element>
  <!--
   ===================================================================
   == IndicatorData class                                           ==
   ===================================================================
  -->
  <xs:element name="IndicatorData">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Indicator"
                    minOccurs="1" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="Indicator">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:IndicatorID"/>
        <xs:element ref="iodef:AlternativeIndicatorID"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:StartTime" minOccurs="0"/>
        <xs:element ref="iodef:EndTime" minOccurs="0"/>
        <xs:element ref="iodef:Confidence" minOccurs="0"/>
        <xs:element ref="iodef:Contact"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:choice>

Danyliw Standards Track [Page 152] RFC 7970 IODEF Version 2 November 2016

          <xs:element ref="iodef:Observable"/>
          <xs:element ref="iodef:ObservableReference"/>
          <xs:element ref="iodef:IndicatorExpression"/>
          <xs:element ref="iodef:IndicatorReference"/>
        </xs:choice>
        <xs:element ref="iodef:NodeRole"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AttackPhase"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Reference"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="IndicatorID">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:ID">
          <xs:attribute name="name" type="xs:string" use="required"/>
          <xs:attribute name="version"
                        type="xs:string" use="required"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="AlternativeIndicatorID">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:IndicatorID" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="Observable">
    <xs:complexType>
      <xs:choice>
        <xs:element ref="iodef:System" minOccurs="0"/>
        <xs:element ref="iodef:Address" minOccurs="0"/>
        <xs:element ref="iodef:DomainData" minOccurs="0"/>

Danyliw Standards Track [Page 153] RFC 7970 IODEF Version 2 November 2016

        <xs:element ref="iodef:Service" minOccurs="0"/>
        <xs:element ref="iodef:EmailData" minOccurs="0"/>
        <xs:element ref="iodef:WindowsRegistryKeysModified"
                         minOccurs="0"/>
        <xs:element ref="iodef:FileData" minOccurs="0"/>
        <xs:element ref="iodef:CertificateData" minOccurs="0"/>
        <xs:element ref="iodef:RegistryHandle" minOccurs="0"/>
        <xs:element ref="iodef:RecordData" minOccurs="0"/>
        <xs:element ref="iodef:EventData" minOccurs="0"/>
        <xs:element ref="iodef:Incident" minOccurs="0"/>
        <xs:element ref="iodef:Expectation" minOccurs="0"/>
        <xs:element ref="iodef:Reference" minOccurs="0"/>
        <xs:element ref="iodef:Assessment" minOccurs="0"/>
        <xs:element ref="iodef:DetectionPattern" minOccurs="0"/>
        <xs:element ref="iodef:HistoryItem" minOccurs="0"/>
        <xs:element ref="iodef:BulkObservable" minOccurs="0"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:choice>
      <xs:attribute name="restriction"
                    type="iodef:restriction-type" use="optional"/>
      <xs:attribute name="ext-restriction"
                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="BulkObservable">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:BulkObservableFormat" minOccurs="0"/>
        <xs:element name="BulkObservableList"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="type"
                    type="bulkobservable-type-type" use="required"/>
      <xs:attribute name="ext-type" type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="bulkobservable-type-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="asn"/>
      <xs:enumeration value="atm"/>
      <xs:enumeration value="e-mail"/>
      <xs:enumeration value="ipv4-addr"/>
      <xs:enumeration value="ipv4-net"/>
      <xs:enumeration value="ipv4-net-mask"/>
      <xs:enumeration value="ipv6-addr"/>
      <xs:enumeration value="ipv6-net"/>

Danyliw Standards Track [Page 154] RFC 7970 IODEF Version 2 November 2016

      <xs:enumeration value="ipv6-net-mask"/>
      <xs:enumeration value="mac"/>
      <xs:enumeration value="site-uri"/>
      <xs:enumeration value="domain-name"/>
      <xs:enumeration value="domain-to-ipv4"/>
      <xs:enumeration value="domain-to-ipv6"/>
      <xs:enumeration value="domain-to-ipv4-timestamp"/>
      <xs:enumeration value="domain-to-ipv6-timestamp"/>
      <xs:enumeration value="ipv4-port"/>
      <xs:enumeration value="ipv6-port"/>
      <xs:enumeration value="windows-reg-key"/>
      <xs:enumeration value="file-hash"/>
      <xs:enumeration value="email-x-mailer"/>
      <xs:enumeration value="email-subject"/>
      <xs:enumeration value="http-user-agent"/>
      <xs:enumeration value="http-request-uri"/>
      <xs:enumeration value="mutex"/>
      <xs:enumeration value="file-path"/>
      <xs:enumeration value="user-name"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="BulkObservableFormat">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:Hash" minOccurs="0"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="BulkObservableList" type="xs:string"/>
  <xs:element name="IndicatorExpression">
    <xs:complexType>
      <xs:sequence maxOccurs="unbounded">
        <xs:choice>
          <xs:element ref="iodef:IndicatorExpression"/>
          <xs:element ref="iodef:Observable"/>
          <xs:element ref="iodef:ObservableReference"/>
          <xs:element ref="iodef:IndicatorReference"/>
        </xs:choice>
        <xs:element ref="iodef:Confidence" minOccurs="0"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="operator"
                    type="indicatorexpression-operator-type"
                    use="optional" default="and"/>
      <xs:attribute name="ext-operator"

Danyliw Standards Track [Page 155] RFC 7970 IODEF Version 2 November 2016

                    type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="indicatorexpression-operator-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="not"/>
      <xs:enumeration value="and"/>
      <xs:enumeration value="or"/>
      <xs:enumeration value="xor"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:element name="ObservableReference">
    <xs:complexType>
      <xs:attribute name="uid-ref" type="xs:IDREF" use="required"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="IndicatorReference">
    <xs:complexType>
      <xs:attribute name="uid-ref" type="xs:IDREF" use="optional"/>
      <xs:attribute name="euid-ref" type="xs:string" use="optional"/>
      <xs:attribute name="version" type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:element name="AttackPhase">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="iodef:AttackPhaseID"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:URL" maxOccurs="unbounded"/>
        <xs:element ref="iodef:Description"
                    minOccurs="0" maxOccurs="unbounded"/>
        <xs:element ref="iodef:AdditionalData"
                    minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="AttackPhaseID" type="xs:string"/>
  <!--
   ===================================================================
   == Miscellaneous classes                                         ==
   ===================================================================
  -->
  <xs:element name="AdditionalData" type="iodef:ExtensionType"/>
  <xs:element name="Description" type="iodef:MLStringType"/>
  <xs:element name="URL" type="xs:anyURI"/>

Danyliw Standards Track [Page 156] RFC 7970 IODEF Version 2 November 2016

  <!--
   ===================================================================
   == IODEF data types                                              ==
   ===================================================================
  -->
  <xs:simpleType name="PositiveFloatType">
    <xs:restriction base="xs:float">
      <xs:minExclusive value="0"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:complexType name="MLStringType">
    <xs:simpleContent>
      <xs:extension base="xs:string">
        <xs:attribute name="translation-id"
                      type="xs:string" use="optional"/>
        <xs:attribute ref="xml:lang"/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>
  <xs:simpleType name="PortlistType">
    <xs:restriction base="xs:string">
      <xs:pattern value="\d+(\-\d+)?(,\d+(\-\d+)?)*"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="TimezoneType">
    <xs:restriction base="xs:string">
      <xs:pattern
       value="Z|[\+\-](0[0-9]|1[0-4]):[0-5][0-9]"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:complexType name="ExtensionType" mixed="true">
    <xs:sequence>
      <xs:any namespace="##any" processContents="lax"
              minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="name" type="xs:string" use="optional"/>
    <xs:attribute name="dtype"
                  type="iodef:dtype-type" use="required"/>
    <xs:attribute name="ext-dtype" type="xs:string" use="optional"/>
    <xs:attribute name="meaning" type="xs:string" use="optional"/>
    <xs:attribute name="formatid" type="xs:string" use="optional"/>
    <xs:attribute name="restriction"
                  type="iodef:restriction-type" use="optional"/>
    <xs:attribute name="ext-restriction"
                  type="xs:string" use="optional"/>
    <xs:attribute name="observable-id" type="xs:ID" use="optional"/>
  </xs:complexType>

Danyliw Standards Track [Page 157] RFC 7970 IODEF Version 2 November 2016

  <xs:complexType name="SoftwareType">
    <xs:sequence>
      <xs:element ref="iodef:SoftwareReference" minOccurs="0"/>
      <xs:element ref="iodef:URL"
                  minOccurs="0" maxOccurs="unbounded"/>
      <xs:element ref="iodef:Description"
                  minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>
  <xs:element name="SoftwareReference">
    <xs:complexType>
      <xs:sequence>
        <xs:any namespace="##any" processContents="lax"
                minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="spec-name"
                    type="softwarereference-spec-name-type"
                    use="required"/>
      <xs:attribute name="ext-spec-name"
                    type="xs:string" use="optional"/>
      <xs:attribute name="dtype"
                    type="softwarereference-dtype-type"
                    use="optional"/>
      <xs:attribute name="ext-dtype" type="xs:string" use="optional"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="softwarereference-spec-name-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="custom"/>
      <xs:enumeration value="cpe"/>
      <xs:enumeration value="swid"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="softwarereference-dtype-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="bytes"/>
      <xs:enumeration value="integer"/>
      <xs:enumeration value="real"/>
      <xs:enumeration value="string"/>
      <xs:enumeration value="xml"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <!--
   ===================================================================
   == Global attribute type declarations                            ==
   ===================================================================

Danyliw Standards Track [Page 158] RFC 7970 IODEF Version 2 November 2016

<xs:simpleType name="yes-no-unknown-type">

    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="yes"/>
      <xs:enumeration value="no"/>
      <xs:enumeration value="unknown"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="restriction-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="default"/>
      <xs:enumeration value="public"/>
      <xs:enumeration value="partner"/>
      <xs:enumeration value="need-to-know"/>
      <xs:enumeration value="private"/>
      <xs:enumeration value="white"/>
      <xs:enumeration value="green"/>
      <xs:enumeration value="amber"/>
      <xs:enumeration value="red"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="severity-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="low"/>
      <xs:enumeration value="medium"/>
      <xs:enumeration value="high"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="duration-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="second"/>
      <xs:enumeration value="minute"/>
      <xs:enumeration value="hour"/>
      <xs:enumeration value="day"/>
      <xs:enumeration value="month"/>
      <xs:enumeration value="quarter"/>
      <xs:enumeration value="year"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="action-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="nothing"/>
      <xs:enumeration value="contact-source-site"/>
      <xs:enumeration value="contact-target-site"/>
      <xs:enumeration value="contact-sender"/>
      <xs:enumeration value="investigate"/>

Danyliw Standards Track [Page 159] RFC 7970 IODEF Version 2 November 2016

      <xs:enumeration value="block-host"/>
      <xs:enumeration value="block-network"/>
      <xs:enumeration value="block-port"/>
      <xs:enumeration value="rate-limit-host"/>
      <xs:enumeration value="rate-limit-network"/>
      <xs:enumeration value="rate-limit-port"/>
      <xs:enumeration value="redirect-traffic"/>
      <xs:enumeration value="honeypot"/>
      <xs:enumeration value="upgrade-software"/>
      <xs:enumeration value="rebuild-asset"/>
      <xs:enumeration value="harden-asset"/>
      <xs:enumeration value="remediate-other"/>
      <xs:enumeration value="status-triage"/>
      <xs:enumeration value="status-new-info"/>
      <xs:enumeration value="watch-and-report"/>
      <xs:enumeration value="defined-coa"/>
      <xs:enumeration value="other"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="dtype-type">
    <xs:restriction base="xs:NMTOKEN">
      <xs:enumeration value="boolean"/>
      <xs:enumeration value="byte"/>
      <xs:enumeration value="bytes"/>
      <xs:enumeration value="character"/>
      <xs:enumeration value="date-time"/>
      <xs:enumeration value="integer"/>
      <xs:enumeration value="ntpstamp"/>
      <xs:enumeration value="portlist"/>
      <xs:enumeration value="real"/>
      <xs:enumeration value="string"/>
      <xs:enumeration value="file"/>
      <xs:enumeration value="path"/>
      <xs:enumeration value="frame"/>
      <xs:enumeration value="packet"/>
      <xs:enumeration value="ipv4-packet"/>
      <xs:enumeration value="ipv6-packet"/>
      <xs:enumeration value="url"/>
      <xs:enumeration value="csv"/>
      <xs:enumeration value="winreg"/>
      <xs:enumeration value="xml"/>
      <xs:enumeration value="ext-value"/>
    </xs:restriction>
  </xs:simpleType>
</xs:schema>

Danyliw Standards Track [Page 160] RFC 7970 IODEF Version 2 November 2016

9. Security Considerations

 The IODEF data model does not directly introduce security or privacy
 issues.  However, as the data encoded by the IODEF might be
 considered sensitive by the parties exchanging it or by those
 described by it, care needs to be taken to ensure appropriate
 handling during the document construction, exchange, processing,
 archiving, subsequent retrieval, and analysis.

9.1. Security

 The underlying messaging format and protocol used to exchange
 instances of the IODEF MUST provide appropriate guarantees of
 confidentiality, integrity, and authenticity.  The use of a
 standardized security protocol is encouraged.  The Real-time Inter-
 network Defense (RID) protocol [RFC6545] and its associated transport
 binding IODEF/RID over HTTP/TLS [RFC6546] provide such security.
 An IODEF implementation may act on the data in the document.  These
 actions might be explicitly requested in the document or the result
 of analytical logic that triggered on data in the document.  For this
 reason, care must be taken by IODEF implementations to properly
 authenticate the sender and receiver of the document.  The sender
 needs confidence that sensitive information and timely requests for
 action are sent to the correct recipient.  The recipient may
 interpret the contents of the document differently based on who sent
 it or vary actions based on the sender.  While the sender of the
 document may explicitly convey confidence in the data in a granular
 way using the Confidence class, the recipient is free to ignore or
 refine this information to make its own assessment.  Ambiguous
 Confidence elements (where it is unclear to which of a set of other
 elements the Confidence element relates) in a document MUST be
 ignored by the recipient.
 Certain classes may require out-of-band coordination to agree upon
 their semantics (e.g., Confidence@rating="low" or DefinedCOA).  This
 coordination MUST occur prior to operational data exchange to prevent
 the incorrect interpretation of these select data elements.  When
 parsing these data elements, implementations should validate, when
 possible, that they conform to the agreed upon semantics.  These
 semantics may need to be periodically reevaluated.
 Executable content of various forms could be embedded into the IODEF
 document directly or through an extension.  Implementation MUST
 handle this content with care to prevent unintentional automated
 execution.  The following classes are explicitly intended to
 represent content that might be executable:

Danyliw Standards Track [Page 161] RFC 7970 IODEF Version 2 November 2016

 o  All classes of type iodef:ExtensionType and the RecordPattern
    class can represent arbitrary binary strings such as legitimate
    software programs or malware.
 o  The EmailMessage and EmailBody classes can represent email
    attachments that can contain arbitrary content.
 o  The DetectionPattern class could specify a machine-readable
    configuration that directs the execution of the corresponding
    tool.
 Per Section 4.3, IODEF implementations will need to periodically
 consult the IANA registries specified in Section 10.2 to discover
 newly registered enumerated attribute values.  These implementations
 MUST communicate with IANA in a way that ensures the integrity of the
 values and the authenticity of the source.  HTTPS over TLS
 [RFC2818][RFC5246] provides such security.

9.2. Privacy

 The IODEF contains numerous fields that are identifiers that could be
 linked to an individual or organization.  IODEF documents may contain
 sensitive information about these identified parties; repeated
 document exchanges about the same and related parties may enable the
 correlation of data about them.  Likewise, a party may report on
 another to a third party without their knowledge.
 When creating an IODEF document, careful consideration must be given
 to what information is shared.  Personal identifiers and attributable
 sensitive information should only be shared when necessary.
 When exchanging documents, transport security MUST provide document-
 level confidentiality.  XML element-level confidentiality can also be
 provided by using [W3C.XMLENC].
 In order to suggest data processing and handling guidelines of the
 encoded information, the IODEF allows a document sender to convey a
 privacy policy using the restriction attribute.  The various
 instances of this attribute allow different data elements of the
 document to be covered by dissimilar policies.  While flexible, it
 must be stressed that this approach only serves as a guideline from
 the sender, as the recipient is free to ignore it.
 Although outside of the scope of an IODEF implementation, the
 contents of IODEF documents and any derived analysis should be
 archived with appropriate confidentiality controls.  Likewise, access
 to retrieve and analyze this data should be restricted to authorized
 users.

Danyliw Standards Track [Page 162] RFC 7970 IODEF Version 2 November 2016

10. IANA Considerations

 This document registers a namespace, an XML schema, and a number of
 registries that map to enumerated values defined in the data model.
 It also defines an Expert Review process for IODEF-related XML
 registry entries.

10.1. Namespace and Schema

 This document uses URNs to describe an XML namespace and schema
 conforming to a registry mechanism described in [RFC3688].
 Registration for the IODEF namespace:
 o  URI: urn:ietf:params:xml:ns:iodef-2.0
 o  Registrant Contact: See the author in the "Author's Address"
    section of this document.
 o  XML: None.  Namespace URIs do not represent an XML specification.
 Registration for the IODEF XML schema:
 o  URI: urn:ietf:params:xml:schema:iodef-2.0
 o  Registrant Contact: See the first author of the "Author's Address"
    section of this document.
 o  XML: See Section 8 of this document.

10.2. Enumerated Value Registries

 This document creates 34 identically structured registries to be
 managed by IANA:
 o  Name of the parent registry: "Incident Object Description Exchange
    Format v2 (IODEF)"
 o  URL of the registry: <http://www.iana.org/assignments/iodef2>
 o  Namespace format: A registry entry consists of:
  • Value. A value for a given IODEF attribute. It MUST conform

to the formatting specified by the IODEF ENUM data type which

       is implemented as an "xs:NMTOKEN" type per Section 3.3.4 of
       [W3C.SCHEMA.DTYPES].  The value SHOULD conform to the
       convention specified in Section 5.2.

Danyliw Standards Track [Page 163] RFC 7970 IODEF Version 2 November 2016

  • Description. A short description of the enumerated value.
  • Reference. An optional list of URIs to further describe the

value.

 o  Allocation policy: Expert Review per [RFC5226].  This reviewer
    will ensure that the requested registry entry conforms to the
    prescribed formatting.  The reviewer will also ensure that the
    entry is an appropriate value for the attribute per the
    information model (Section 3).
 The registries to be created are named in the "Registry Name" column
 of Table 1.  Each registry is initially populated with values and
 descriptions that come from an attribute specified in the IODEF
 schema (Section 8) whose description is found in a sub-section of the
 information model (Section 3).  The initial values for the Value and
 Description fields of a given registry are listed in the "IV (Value)"
 and "IV (Desc.)" columns, respectively.  The "IV (Value)" points to a
 given schema type per Section 8.  Each enumerated value in the schema
 gets a corresponding entry in a given registry.  The "IV (Desc.)"
 points to a section in the text of this document that describes each
 enumerated value.  The initial value of the Reference field of every
 registry entry described below should be this document.

Danyliw Standards Track [Page 164] RFC 7970 IODEF Version 2 November 2016

 +-------------------------+-----------------------------+-----------+
 |      Registry Name      |          IV (Value)         |     IV    |
 |                         |                             |  (Desc.)  |
 +-------------------------+-----------------------------+-----------+
 |       Restriction       |    iodef-restriction-type   |   3.3.1   |
 |                         |                             |           |
 |     Incident-purpose    |    incident-purpose-type    |    3.2    |
 |                         |                             |           |
 |     Incident-status     |     incident-status-type    |    3.2    |
 |                         |                             |           |
 |       Contact-role      |      contact-role-type      |    3.9    |
 |                         |                             |           |
 |       Contact-type      |      contact-type-type      |    3.9    |
 |                         |                             |           |
 | RegistryHandle-registry |   registryhandle-registry-  |   3.9.1   |
 |                         |             type            |           |
 |                         |                             |           |
 |    PostalAddress-type   |   postaladdress-type-type   |   3.9.2   |
 |                         |                             |           |
 |      Telephone-type     |     telephone-type-type     |   3.9.4   |
 |                         |                             |           |
 |        Email-type       |       email-type-type       |   3.9.3   |
 |                         |                             |           |
 |    Expectation-action   |         action-type         |    3.15   |
 |                         |                             |           |
 |     Discovery-source    |    discovery-source-type    |    3.10   |
 |                         |                             |           |
 |    SystemImpact-type    |    systemimpact-type-type   |   3.12.1  |
 |                         |                             |           |
 | BusinessImpact-severity |   businessimpact-severity-  |   3.12.2  |
 |                         |             type            |           |
 |                         |                             |           |
 |   BusinessImpact-type   |   businessimpact-type-type  |   3.12.2  |
 |                         |                             |           |
 |    TimeImpact-metric    |    timeimpact-metric-type   |   3.12.3  |
 |                         |                             |           |
 |   TimeImpact-duration   |        duration-type        |   3.12.3  |
 |                         |                             |           |
 |    Confidence-rating    |    confidence-rating-type   |   3.12.5  |
 |                         |                             |           |
 |    NodeRole-category    |    noderole-category-type   |   3.18.2  |
 |                         |                             |           |
 |     System-category     |     system-category-type    |    3.17   |
 |                         |                             |           |
 |     System-ownership    |    system-ownership-type    |    3.17   |
 |                         |                             |           |
 |     Address-category    |    address-category-type    |   3.18.1  |
 |                         |                             |           |

Danyliw Standards Track [Page 165] RFC 7970 IODEF Version 2 November 2016

 |       Counter-type      |      counter-type-type      |   3.18.3  |
 |                         |                             |           |
 |       Counter-unit      |      counter-unit-type      |   3.18.3  |
 |                         |                             |           |
 |    DomainData-system-   |  domaindata-system-status-  |    3.19   |
 |          status         |             type            |           |
 |                         |                             |           |
 |    DomainData-domain-   |  domaindata-domain-status-  |    3.19   |
 |          status         |             type            |           |
 |                         |                             |           |
 |    RecordPattern-type   |   recordpattern-type-type   |   3.22.2  |
 |                         |                             |           |
 |      RecordPattern-     |  recordpattern-offsetunit-  |   3.22.2  |
 |        offsetunit       |             type            |           |
 |                         |                             |           |
 |    Key-registryaction   |   key-registryaction-type   |   3.23.1  |
 |                         |                             |           |
 |      HashData-scope     |     hashdata-scope-type     |    3.26   |
 |                         |                             |           |
 |   BulkObservable-type   |   bulkobservable-type-type  |  3.29.3.1 |
 |                         |                             |           |
 |   IndicatorExpression-  |     indicatorexpression-    |   3.29.4  |
 |         operator        |        operator-type        |           |
 |                         |                             |           |
 |   ExtensionType-dtype   |          dtype-type         |    2.16   |
 |                         |                             |           |
 | SoftwareReference-spec- |  softwarereference-spec-id- |   2.15.1  |
 |            id           |             type            |           |
 |                         |                             |           |
 | SoftwareReference-dtype |   softwarereference-dtype-  |   2.15.1  |
 |                         |             type            |           |
 +-------------------------+-----------------------------+-----------+
               Table 1: IANA Enumerated Value Registries

10.3. Expert Review of IODEF-Related XML Registry Entries

 IODEF class extensions, per Section 5.2, could register their
 namespaces and schemas with the IANA XML namespace ("ns" on
 <http://www.iana.org/assignments/xml-registry/>) and schema
 registries ("schema" on <http://www.iana.org/assignments/
 xml-registry/>) described in [RFC3688].  In addition to any reviews
 required by IANA, changes to the XML "schema" registry for schema
 names beginning with "urn:ietf:params:xml:schema:iodef" are subject
 to an additional IODEF Expert Review [RFC5226] to ensure
 compatibility with IODEF and other existing IODEF extensions.

Danyliw Standards Track [Page 166] RFC 7970 IODEF Version 2 November 2016

 The IODEF expert(s) for these reviews will be designated by the IETF
 Security Area Directors.
 This document obsoletes [RFC6685].

11. References

11.1. Normative References

 [E.164]    ITU Telecommunication Standardization Sector, "The
            International Public Telecommunication Numbering Plan",
            ITU-T Recommendation E.164, November 2010.
 [IANA.Media]
            IANA, "Media Types",
            <http://www.iana.org/assignments/media-types/>.
 [IANA.Ports]
            IANA, "Service Name and Transport Protocol Port Number
            Registry", <http://www.iana.org/assignments/
            service-names-port-numbers/>.
 [IANA.Protocols]
            IANA, "Assigned Internet Protocol Numbers",
            <http://www.iana.org/assignments/protocol-numbers/>.
 [IEEE.POSIX]
            IEEE, "Information Technology - Portable Operating System
            Interface (POSIX) Base Specifications, Issue 7", IEEE
            Std 1003.1-2001, DOI 10.1109/IEEESTD.2009.5393893,
            September 2009.
 [ISO19770] International Organization for Standardization,
            "Information technology -- Software asset management --
            Part 2: Software identification tag", ISO
            Standard 19770-2:2015, October 2015.
 [ISO4217]  International Organization for Standardization, "Codes for
            the representation of currencies", ISO 4217:2015, 2015.
 [NIST.CPE] Cheikes, B., Waltermire, D., and K. Scarfone, "Common
            Platform Enumeration: Naming Specification Version 2.3",
            NIST Interagency Report 7695, August 2011,
            <http://csrc.nist.gov/publications/nistir/ir7695/
            NISTIR-7695-CPE-Naming.pdf>.

Danyliw Standards Track [Page 167] RFC 7970 IODEF Version 2 November 2016

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC2781]  Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO
            10646", RFC 2781, DOI 10.17487/RFC2781, February 2000,
            <http://www.rfc-editor.org/info/rfc2781>.
 [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
            10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
            2003, <http://www.rfc-editor.org/info/rfc3629>.
 [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
            DOI 10.17487/RFC3688, January 2004,
            <http://www.rfc-editor.org/info/rfc3688>.
 [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
            Resource Identifier (URI): Generic Syntax", STD 66,
            RFC 3986, DOI 10.17487/RFC3986, January 2005,
            <http://www.rfc-editor.org/info/rfc3986>.
 [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
            Architecture", RFC 4291, DOI 10.17487/RFC4291, February
            2006, <http://www.rfc-editor.org/info/rfc4291>.
 [RFC4519]  Sciberras, A., Ed., "Lightweight Directory Access Protocol
            (LDAP): Schema for User Applications", RFC 4519,
            DOI 10.17487/RFC4519, June 2006,
            <http://www.rfc-editor.org/info/rfc4519>.
 [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
            DOI 10.17487/RFC5322, October 2008,
            <http://www.rfc-editor.org/info/rfc5322>.
 [RFC5646]  Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
            Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
            September 2009, <http://www.rfc-editor.org/info/rfc5646>.
 [RFC5952]  Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
            Address Text Representation", RFC 5952,
            DOI 10.17487/RFC5952, August 2010,
            <http://www.rfc-editor.org/info/rfc5952>.
 [RFC6531]  Yao, J. and W. Mao, "SMTP Extension for Internationalized
            Email", RFC 6531, DOI 10.17487/RFC6531, February 2012,
            <http://www.rfc-editor.org/info/rfc6531>.

Danyliw Standards Track [Page 168] RFC 7970 IODEF Version 2 November 2016

 [RFC7203]  Takahashi, T., Landfield, K., and Y. Kadobayashi, "An
            Incident Object Description Exchange Format (IODEF)
            Extension for Structured Cybersecurity Information",
            RFC 7203, DOI 10.17487/RFC7203, April 2014,
            <http://www.rfc-editor.org/info/rfc7203>.
 [RFC7495]  Montville, A. and D. Black, "Enumeration Reference Format
            for the Incident Object Description Exchange Format
            (IODEF)", RFC 7495, DOI 10.17487/RFC7495, March 2015,
            <http://www.rfc-editor.org/info/rfc7495>.
 [W3C.SCHEMA]
            Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn,
            "XML Schema Part 1: Structures Second Edition", W3C
            Recommendation REC-xmlschema-1-20041028, October 2004,
            <http://www.w3.org/TR/xmlschema-1/>.
 [W3C.SCHEMA.DTYPES]
            Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes
            Second Edition", W3C Recommendation REC-xmlschema-
            2-20041028, October 2004,
            <http://www.w3.org/TR/xmlschema-2/>.
 [W3C.XML]  Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
            F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
            Edition)", W3C Recommendation REC-xml-20081126, November
            2008, <http://www.w3.org/TR/2008/REC-xml-20081126/>.
 [W3C.XMLNS]
            Bray, T., Hollander, D., Layman, A., Tobin, R., and H.
            Thompson, "Namespaces in XML 1.0 (Third Edition)", W3C
            Recommendation REC-xml-names-20091208, December 2009,
            <http://www.w3.org/TR/2009/REC-xml-names-20091208/>.
 [W3C.XMLSIG]
            Eastlake, D., Reagle, J., Solo, D., Hirsch, F., and T.
            Roessler, "XML Signature Syntax and Processing (Second
            Edition)", W3C Recommendation REC-xmldsig-core-20080610,
            June 2008, <http://www.w3.org/TR/xmldsig-core/>.
 [W3C.XPATH]
            Robie, J., Dyck, M., and J. Spiegel, "XML Path Language
            (XPath) 3.1", W3C Candidate Recommendation CR-xpath-
            31-20151217, December 2015,
            <https://www.w3.org/TR/xpath-3/>.

Danyliw Standards Track [Page 169] RFC 7970 IODEF Version 2 November 2016

11.2. Informative References

 [KB310516] Microsoft Corporation, "How to add, modify, or delete
            registry subkeys and values by using a .reg file",
            September 2013,
            <https://support.microsoft.com/en-us/kb/310516>.
 [NIST800.61rev2]
            National Institute of Standards and Technology, "Computer
            Security Incident Handling Guide", NIST Special
            Publication 800-61, Revision 2, August 2012,
            <http://dx.doi.org/10.6028/NIST.SP.800-61r2>.
 [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
            DOI 10.17487/RFC2818, May 2000,
            <http://www.rfc-editor.org/info/rfc2818>.
 [RFC3982]  Newton, A. and M. Sanz, "IRIS: A Domain Registry (dreg)
            Type for the Internet Registry Information Service
            (IRIS)", RFC 3982, DOI 10.17487/RFC3982, January 2005,
            <http://www.rfc-editor.org/info/rfc3982>.
 [RFC4180]  Shafranovich, Y., "Common Format and MIME Type for Comma-
            Separated Values (CSV) Files", RFC 4180,
            DOI 10.17487/RFC4180, October 2005,
            <http://www.rfc-editor.org/info/rfc4180>.
 [RFC5070]  Danyliw, R., Meijer, J., and Y. Demchenko, "The Incident
            Object Description Exchange Format", RFC 5070,
            DOI 10.17487/RFC5070, December 2007,
            <http://www.rfc-editor.org/info/rfc5070>.
 [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", BCP 26, RFC 5226,
            DOI 10.17487/RFC5226, May 2008,
            <http://www.rfc-editor.org/info/rfc5226>.
 [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
            (TLS) Protocol Version 1.2", RFC 5246,
            DOI 10.17487/RFC5246, August 2008,
            <http://www.rfc-editor.org/info/rfc5246>.
 [RFC5901]  Cain, P. and D. Jevans, "Extensions to the IODEF-Document
            Class for Reporting Phishing", RFC 5901,
            DOI 10.17487/RFC5901, July 2010,
            <http://www.rfc-editor.org/info/rfc5901>.

Danyliw Standards Track [Page 170] RFC 7970 IODEF Version 2 November 2016

 [RFC6545]  Moriarty, K., "Real-time Inter-network Defense (RID)",
            RFC 6545, DOI 10.17487/RFC6545, April 2012,
            <http://www.rfc-editor.org/info/rfc6545>.
 [RFC6546]  Trammell, B., "Transport of Real-time Inter-network
            Defense (RID) Messages over HTTP/TLS", RFC 6546,
            DOI 10.17487/RFC6546, April 2012,
            <http://www.rfc-editor.org/info/rfc6546>.
 [RFC6685]  Trammell, B., "Expert Review for Incident Object
            Description Exchange Format (IODEF) Extensions in IANA XML
            Registry", RFC 6685, DOI 10.17487/RFC6685, July 2012,
            <http://www.rfc-editor.org/info/rfc6685>.
 [W3C.XMLENC]
            Eastlake, D., Reagle, J., Solo, D., Hirsch, F., Nystrom,
            M., Roessler, T., and K. Yiu, "XML Encryption Syntax and
            Processing Version 1.1", W3C Recommendation REC-xmldsig-
            core1-20130411, April 2013,
            <https://www.w3.org/TR/xmlenc-core1/>.

Acknowledgments

 Thanks to Paul Stoecker for his editorial leadership in the
 transition of an early draft to the current document.
 Thanks to Kathleen Moriarty, Brian Trammel, Alexey Melnikov, Takeshi
 Takahashi, David Waltermire, and Sean Turner (as the MILE working
 group chairs, secretary, and area directors) for providing feedback
 and coordination of this document.
 Thanks to the following individuals (listed alphabetically) who
 provided feedback during the meetings, on the mailing list, or
 through implementation experience: Jerome Athias, David Black, Eric
 Burger, Toma Cejka, Patrick Curry, John Field, Christopher
 Harrington, Chris Inacio, Panos Kampanakis, David Misell, Daisuke
 Miyamoto, Adam Montville, Robert Moskowitz, Lagadec Philippe, Tony
 Rutkowski, Mio Suzuki, and Nik Teague.

Danyliw Standards Track [Page 171] RFC 7970 IODEF Version 2 November 2016

Author's Address

 Roman Danyliw
 CERT
 Software Engineering Institute
 Carnegie Mellon University
 4500 Fifth Avenue
 Pittsburgh, PA
 United States of America
 Email: rdd@cert.org

Danyliw Standards Track [Page 172]

/data/webs/external/dokuwiki/data/pages/rfc/rfc7970.txt · Last modified: 2016/11/30 23:40 (external edit)