MILE Working Group R. Danyliw Internet-Draft CERT Obsoletes: 5070 (if approved) P. Stoecker Intended status: Standards Track RSA Expires: March 02, 2014 August 29, 2013 The Incident Object Description Exchange Format v2 draft-ietf-mile-rfc5070-bis-01 Abstract The Incident Object Description Exchange Format (IODEF) defines a data representation that provides a framework for sharing information commonly exchanged by Computer Security Incident Response Teams (CSIRTs) about computer security incidents. This document describes the information model for the IODEF and provides an associated data model specified with XML Schema. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of Danyliw & Stoecker Expires March 02, 2014 [Page 1] Internet-Draft IODEF August 2013 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Changes from 5070 . . . . . . . . . . . . . . . . . . . . 5 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 1.3. Notations . . . . . . . . . . . . . . . . . . . . . . . . 6 1.4. About the IODEF Data Model . . . . . . . . . . . . . . . 6 1.5. About the IODEF Implementation . . . . . . . . . . . . . 7 2. IODEF Data Types . . . . . . . . . . . . . . . . . . . . . . 7 2.1. Integers . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2. Real Numbers . . . . . . . . . . . . . . . . . . . . . . 8 2.3. Characters and Strings . . . . . . . . . . . . . . . . . 8 2.4. Multilingual Strings . . . . . . . . . . . . . . . . . . 8 2.5. Bytes . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.6. Hexadecimal Bytes . . . . . . . . . . . . . . . . . . . . 8 2.7. Enumerated Types . . . . . . . . . . . . . . . . . . . . 9 2.8. Date-Time Strings . . . . . . . . . . . . . . . . . . . . 9 2.9. Timezone String . . . . . . . . . . . . . . . . . . . . . 9 2.10. Port Lists . . . . . . . . . . . . . . . . . . . . . . . 9 2.11. Postal Address . . . . . . . . . . . . . . . . . . . . . 10 2.12. Person or Organization . . . . . . . . . . . . . . . . . 10 2.13. Telephone and Fax Numbers . . . . . . . . . . . . . . . . 10 2.14. Email String . . . . . . . . . . . . . . . . . . . . . . 10 2.15. Uniform Resource Locator strings . . . . . . . . . . . . 10 3. The IODEF Data Model . . . . . . . . . . . . . . . . . . . . 10 3.1. IODEF-Document Class . . . . . . . . . . . . . . . . . . 11 3.2. Incident Class . . . . . . . . . . . . . . . . . . . . . 11 3.3. IncidentID Class . . . . . . . . . . . . . . . . . . . . 15 3.4. AlternativeID Class . . . . . . . . . . . . . . . . . . . 16 3.5. RelatedActivity Class . . . . . . . . . . . . . . . . . . 16 3.6. AdditionalData Class . . . . . . . . . . . . . . . . . . 17 3.7. Contact Class . . . . . . . . . . . . . . . . . . . . . . 19 3.7.1. RegistryHandle Class . . . . . . . . . . . . . . . . 22 Danyliw & Stoecker Expires March 02, 2014 [Page 2] Internet-Draft IODEF August 2013 3.7.2. PostalAddress Class . . . . . . . . . . . . . . . . . 22 3.7.3. Email Class . . . . . . . . . . . . . . . . . . . . . 23 3.7.4. Telephone and Fax Classes . . . . . . . . . . . . . . 23 3.8. Time Classes . . . . . . . . . . . . . . . . . . . . . . 24 3.8.1. StartTime . . . . . . . . . . . . . . . . . . . . . . 24 3.8.2. EndTime . . . . . . . . . . . . . . . . . . . . . . . 24 3.8.3. DetectTime . . . . . . . . . . . . . . . . . . . . . 24 3.8.4. ReportTime . . . . . . . . . . . . . . . . . . . . . 25 3.8.5. DateTime . . . . . . . . . . . . . . . . . . . . . . 25 3.9. Method Class . . . . . . . . . . . . . . . . . . . . . . 25 3.9.1. Reference Class . . . . . . . . . . . . . . . . . . . 26 3.10. Assessment Class . . . . . . . . . . . . . . . . . . . . 27 3.10.1. Impact Class . . . . . . . . . . . . . . . . . . . . 28 3.10.2. TimeImpact Class . . . . . . . . . . . . . . . . . . 30 3.10.3. MonetaryImpact Class . . . . . . . . . . . . . . . . 32 3.10.4. Confidence Class . . . . . . . . . . . . . . . . . . 32 3.11. History Class . . . . . . . . . . . . . . . . . . . . . . 33 3.11.1. HistoryItem Class . . . . . . . . . . . . . . . . . 34 3.12. EventData Class . . . . . . . . . . . . . . . . . . . . . 35 3.12.1. Relating the Incident and EventData Classes . . . . 37 3.12.2. Cardinality of EventData . . . . . . . . . . . . . . 38 3.13. Expectation Class . . . . . . . . . . . . . . . . . . . . 39 3.14. Flow Class . . . . . . . . . . . . . . . . . . . . . . . 41 3.15. System Class . . . . . . . . . . . . . . . . . . . . . . 42 3.16. Node Class . . . . . . . . . . . . . . . . . . . . . . . 44 3.16.1. Counter Class . . . . . . . . . . . . . . . . . . . 45 3.16.2. Address Class . . . . . . . . . . . . . . . . . . . 46 3.16.3. NodeRole Class . . . . . . . . . . . . . . . . . . . 48 3.17. Service Class . . . . . . . . . . . . . . . . . . . . . . 50 3.17.1. Application Class . . . . . . . . . . . . . . . . . 51 3.18. OperatingSystem Class . . . . . . . . . . . . . . . . . . 53 3.19. Record Class . . . . . . . . . . . . . . . . . . . . . . 53 3.19.1. RecordData Class . . . . . . . . . . . . . . . . . . 53 3.19.2. RecordPattern Class . . . . . . . . . . . . . . . . 55 3.19.3. RecordItem Class . . . . . . . . . . . . . . . . . . 56 3.20. RegistryKeyModified Class . . . . . . . . . . . . . . . . 56 3.20.1. Key Class . . . . . . . . . . . . . . . . . . . . . 57 3.21. HashInformation Class . . . . . . . . . . . . . . . . . . 58 4. Processing Considerations . . . . . . . . . . . . . . . . . . 59 4.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . 60 4.2. IODEF Namespace . . . . . . . . . . . . . . . . . . . . . 60 4.3. Validation . . . . . . . . . . . . . . . . . . . . . . . 60 5. Extending the IODEF . . . . . . . . . . . . . . . . . . . . . 61 5.1. Extending the Enumerated Values of Attributes . . . . . . 62 5.2. Extending Classes . . . . . . . . . . . . . . . . . . . . 62 6. Internationalization Issues . . . . . . . . . . . . . . . . . 64 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 65 7.1. Worm . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Danyliw & Stoecker Expires March 02, 2014 [Page 3] Internet-Draft IODEF August 2013 7.2. Reconnaissance . . . . . . . . . . . . . . . . . . . . . 67 7.3. Bot-Net Reporting . . . . . . . . . . . . . . . . . . . . 69 7.4. Watch List . . . . . . . . . . . . . . . . . . . . . . . 71 8. The IODEF Schema . . . . . . . . . . . . . . . . . . . . . . 72 9. Security Considerations . . . . . . . . . . . . . . . . . . . 104 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 105 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 105 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 106 12.1. Normative References . . . . . . . . . . . . . . . . . . 106 12.2. Informative References . . . . . . . . . . . . . . . . . 107 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 bot- network, or sharing watch-lists of known malicious IP addresses 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). It provides an XML representation for conveying: o cyber intelligence to characterize threats; o cyber incident reports to document particular cyber security events or relationships between events; o cyber event mitigation to request proactive and reactive mitigation approaches to cyber intelligence or incidents; and o cyber information sharing meta-data so that these various classes of information can be exchanged among parties. The data model encodes information about hosts, networks, and the services running on these systems; attack methodology and associated forensic evidence; impact of the activity; and limited approaches for documenting workflow. The overriding purpose of the IODEF is to enhance the operational capabilities of CSIRTs. Community adoption of the IODEF provides an improved ability to resolve incidents and convey situational awareness by simplifying collaboration and data sharing. This structured format provided by the IODEF allows for: Danyliw & Stoecker Expires March 02, 2014 [Page 4] Internet-Draft IODEF August 2013 o increased automation in processing of incident data, since the resources of security analysts to parse free-form textual documents will be reduced; o decreased effort in normalizing similar data (even when highly structured) from different sources; and o a common format on which to build interoperable tools for incident handling and subsequent analysis, specifically when data comes from multiple constituencies. Coordinating with other CSIRTs is not strictly a technical problem. There are numerous procedural, trust, and legal considerations that might prevent an organization from sharing information. The IODEF does not attempt to address them. However, operational implementations of the IODEF will need to consider this broader context. Sections 3 and 8 specify the IODEF data model with text and an XML schema. The types used by the data model are covered in Section 2. Processing considerations, the handling of extensions, and internationalization issues related to the data model are covered in Sections 4, 5, and 6, respectively. Examples are listed in Section 7. Section 1 provides the background for the IODEF, and Section 9 documents the security considerations. 1.1. Changes from 5070 This document contains changes with respect to its predecessor RFC5070. o All of the RFC5070 Errata was implemented. o Imported the xmlns:ds namespace to include digital signature hash classes. o The attributes @indicator-uid and @indicator-set-id were added to various classes to reference commonly shared indicators. o The following classes were added to the Service class: Email, EmailSubject, X-Mailer, and DomainData. o The following classes were added to the Record class: FileName, ds:Reference, and WindowsRegistryKeysModified. o (for consideration) The following class was added to the Node class: URL. Danyliw & Stoecker Expires March 02, 2014 [Page 5] Internet-Draft IODEF August 2013 o (for consideration) The following attributes was added to the SoftwareType complexType: user-agent. o Additional enumerated values were added to the following attributes: @restriction, {Expectation, HistoryItem}@action, and NodeRole@category. 1.2. 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 [6]. Definitions for some of the common computer security-related terminology used in this document can be found in Section 2 of [16]. 1.3. Notations The normative IODEF data model is specified with the text in Section 3 and the XML schema in Section 8. To help 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. 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 specific elements and attributes of the IODEF schema. The terms "class" and "element" will be used interchangeably to reference either the corresponding data element in the information or data models, respectively. 1.4. About the IODEF Data Model The IODEF data model is a data representation that provides a framework for sharing information commonly exchanged by CSIRTs about computer security incidents. A number of considerations were made in the design of the data model. o The data model serves as a transport format. Therefore, its specific representation is not the optimal representation for on- disk storage, long-term archiving, or in-memory processing. o As there is no precise widely agreed upon definition for an incident, the data model does not attempt to dictate one through its implementation. Rather, a broad understanding is assumed in the IODEF that is flexible enough to encompass most operators. Danyliw & Stoecker Expires March 02, 2014 [Page 6] Internet-Draft IODEF August 2013 o Describing an incident for all definitions would require an extremely complex data model. Therefore, the IODEF only intends to be a framework to convey commonly exchanged incident information. It ensures that there are ample mechanisms for extensibility to support organization-specific information, and techniques to reference information kept outside of the explicit data model. o The domain of security analysis is not fully standardized and must rely on free-form textual descriptions. The IODEF attempts to strike a balance between supporting this free-form content, while still allowing automated processing of incident information. o The IODEF is only one of several security relevant data representations being standardized. Attempts were made to ensure they were complimentary. The data model of the Intrusion Detection Message Exchange Format [17] influenced the design of the IODEF. Further discussion of the desirable properties for the IODEF can be found in the Requirements for the Format for Incident Information Exchange (FINE) [16]. 1.5. About the IODEF Implementation The IODEF implementation is specified as an Extensible Markup Language (XML) [1] Schema [2] in Section 8. Implementing the IODEF in XML provides numerous advantages. Its extensibility makes it ideal for specifying a data encoding framework that supports various character encodings. Likewise, the abundance of related technologies (e.g., XSL, XPath, XML-Signature) makes for simplified manipulation. However, XML is fundamentally a text representation, which makes it inherently inefficient when binary data must be embedded or large volumes of data must be exchanged. 2. IODEF Data Types The various data elements of the IODEF data model are typed. This section discusses these data types. When possible, native Schema data types were adopted, but for more complicated formats, regular expressions (see Appendix F of [3]) or external standards were used. Danyliw & Stoecker Expires March 02, 2014 [Page 7] Internet-Draft IODEF August 2013 2.1. Integers An integer is represented by the INTEGER data type. Integer data MUST be encoded in Base 10. The INTEGER data type is implemented as an "xs:integer" [3] in the schema. 2.2. Real Numbers Real (floating-point) attributes are represented by the REAL data type. Real data MUST be encoded in Base 10. The REAL data type is implemented as an "xs:float" [3] in the schema. 2.3. Characters and Strings A single character is represented by the CHARACTER data type. A character 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 implement as an "xs:string" [3] in the schema. 2.4. Multilingual Strings STRING data that represents multi-character attributes in a language different than the default encoding of the document is of the ML_STRING data type. The ML_STRING data type is implemented as an "iodef:MLStringType" in the schema. 2.5. Bytes A binary octet is represented by the BYTE data type. A sequence of binary octets is represented by the BYTE[] data type. These octets are encoded using base64. The BYTE data type is implemented as an "xs:base64Binary" [3] in the schema. 2.6. Hexadecimal Bytes A binary octet is represented by the HEXBIN (and HEXBIN[]) data type. This octet is encoded as a character tuple consisting of two hexadecimal digits. Danyliw & Stoecker Expires March 02, 2014 [Page 8] Internet-Draft IODEF August 2013 The HEXBIN data type is implemented as an "xs:hexBinary" [3] in the schema. 2.7. Enumerated Types Enumerated types are represented by the ENUM data type, and consist of an ordered list of acceptable values. Each value has a representative keyword. Within the IODEF schema, the enumerated type keywords are used as attribute values. The ENUM data type is implemented as a series of "xs:NMTOKEN" in the schema. 2.8. Date-Time Strings Date-time strings are represented by the DATETIME data type. Each date-time string identifies a particular instant in time; ranges are not supported. Date-time strings are formatted according to a subset of ISO 8601:2000 [13] documented in RFC 3339 [12]. The DATETIME data type is implemented as an "xs:dateTime" [3] in the schema. 2.9. Timezone String A timezone offset from UTC is represented 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 as an "xs:string" with a regular expression constraint in the schema. This regular expression is identical to the timezone representation implemented in an "xs:dateTime". 2.10. Port Lists A list of network ports are represented 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". The PORTLIST data type is implemented as an "xs:string" with a regular expression constraint in the schema. Danyliw & Stoecker Expires March 02, 2014 [Page 9] Internet-Draft IODEF August 2013 2.11. Postal Address A postal address is represented by the POSTAL data type. This data type is an ML_STRING whose format is documented in Section 2.23 of RFC 4519 [10]. It defines a postal address as a free-form multi-line string separated by the "$" character. The POSTAL data type is implemented as an "xs:string" in the schema. 2.12. Person or Organization The name of an individual or organization is represented by the NAME data type. This data type is an ML_STRING whose format is documented in Section 2.3 of RFC 4519 [10]. The NAME data type is implemented as an "xs:string" in the schema. 2.13. Telephone and Fax Numbers A telephone or fax number is represented by the PHONE data type. The format of the PHONE data type is documented in Section 2.35 of RFC 4519 [10]. The PHONE data type is implemented as an "xs:string" in the schema. 2.14. Email String An email address is represented by the EMAIL data type. The format of the EMAIL data type is documented in Section 3.4.1 RFC 2822 [11] The EMAIL data type is implemented as an "xs:string" in the schema. 2.15. Uniform Resource Locator strings A uniform resource locator (URL) is represented by the URL data type. The format of the URL data type is documented in RFC 2396 [8]. The URL data type is implemented as an "xs:anyURI" in the schema. 3. The IODEF Data Model In this section, the individual components of the IODEF data model will be discussed in detail. For each class, the semantics will be described and the relationship with other classes will be depicted with UML. When necessary, specific comments will be made about corresponding definition in the schema in Section 8 Danyliw & Stoecker Expires March 02, 2014 [Page 10] Internet-Draft IODEF August 2013 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 lang | | STRING formatid | +-----------------+ Figure 1: IODEF-Document Class The aggregate class that constitute IODEF-Document is: Incident One or more. The information related to a single incident. The IODEF-Document class has three attributes: version Required. STRING. The IODEF specification version number to which this IODEF document conforms. The value of this attribute MUST be "2.00" lang Required. ENUM. A valid language code per RFC 4646 [7] constrained by the definition of "xs:language". The interpretation of this code is described in Section 6. formatid Optional. STRING. A free-form string to convey processing instructions to the recipient of the document. Its semantics must be negotiated out-of-band. 3.2. Incident Class Every incident is represented by an instance of the Incident class. This class provides a standardized representation for commonly exchanged incident data. +--------------------+ | Incident | +--------------------+ | ENUM purpose |<>----------[ IncidentID ] | STRING ext-purpose |<>--{0..1}--[ AlternativeID ] Danyliw & Stoecker Expires March 02, 2014 [Page 11] Internet-Draft IODEF August 2013 | ENUM lang |<>--{0..1}--[ RelatedActivity ] | ENUM restriction |<>--{0..1}--[ DetectTime ] | |<>--{0..1}--[ StartTime ] | |<>--{0..1}--[ EndTime ] | |<>----------[ ReportTime ] | |<>--{0..*}--[ Description ] | |<>--{1..*}--[ Assessment ] | |<>--{0..*}--[ Method ] | |<>--{1..*}--[ Contact ] | |<>--{0..*}--[ EventData ] | |<>--{0..1}--[ History ] | |<>--{0..*}--[ AdditionalData ] +--------------------+ Figure 2: The Incident Class The aggregate classes that constitute Incident are: IncidentID One. An incident tracking number assigned to this incident by the CSIRT that generated the IODEF document. AlternativeID Zero or one. The incident tracking numbers used by other CSIRTs to refer to the incident described in the document. RelatedActivity Zero or one. The incident tracking numbers of related incidents. DetectTime Zero or one. The time the incident was first detected. StartTime Zero or one. The time the incident started. EndTime Zero or one. The time the incident ended. ReportTime One. The time the incident was reported. Description Zero or more. ML_STRING. A free-form textual description of the incident. Assessment One or more. A characterization of the impact of the incident. Danyliw & Stoecker Expires March 02, 2014 [Page 12] Internet-Draft IODEF August 2013 Method Zero or more. The techniques used by the intruder in the incident. Contact One or more. Contact information for the parties involved in the incident. EventData Zero or more. Description of the events comprising the incident. History Zero or one. A log of significant events or actions that occurred during the course of handling the incident. AdditionalData Zero or more. Mechanism by which to extend the data model. The Incident class has five attributes: purpose Required. ENUM. The purpose attribute represents the reason why the IODEF document was created. It is closely related to the Expectation class (Section 3.13). This attribute is defined as an enumerated list: 1. traceback. The document was sent for trace-back purposes. 2. mitigation. The document was sent to request aid in mitigating the described activity. 3. reporting. The document was sent to comply with reporting requirements. 4. other. The document was sent for purposes specified in the Expectation class. 5. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-purpose Optional. STRING. A means by which to extend the purpose attribute. See Section 5.1. lang Optional. ENUM. A valid language code per RFC 4646 [7] constrained by the definition of "xs:language". The interpretation of this code is described in Section 6. Danyliw & Stoecker Expires March 02, 2014 [Page 13] Internet-Draft IODEF August 2013 restriction Optional. ENUM. This 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 specified 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. 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. 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'. Danyliw & Stoecker Expires March 02, 2014 [Page 14] Internet-Draft IODEF August 2013 8. amber. Same as 'need-to-know'. 9. red. Same as 'private'. indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. 3.3. IncidentID Class The IncidentID class represents an incident tracking number that is unique in the context of the CSIRT and identifies the activity characterized in an IODEF Document. This identifier would serve as an index into the CSIRT incident handling 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 | +------------------+ Figure 3: The IncidentID Class The IncidentID class has three attributes: 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. instance Optional. STRING. An identifier referencing a subset of the named incident. restriction Optional. ENUM. This attribute has been defined in Section 3.2. The default value is "public". Danyliw & Stoecker Expires March 02, 2014 [Page 15] Internet-Draft IODEF August 2013 3.4. AlternativeID Class The AlternativeID class lists the incident tracking numbers used by CSIRTs, other than the one generating the document, to refer to the identical activity described the IODEF document. A tracking number listed as an AlternativeID references the same incident detected by another CSIRT. The incident tracking numbers of the CSIRT that generated the IODEF document must never be considered an AlternativeID. +------------------+ | AlternativeID | +------------------+ | ENUM restriction |<>--{1..*}--[ IncidentID ] | | +------------------+ Figure 4: The AlternativeID Class The aggregate class that constitutes AlternativeID is: IncidentID One or more. The incident tracking number of another CSIRT. The AlternativeID class has one attribute: restriction Optional. ENUM. This attribute has been defined in Section 3.2. 3.5. RelatedActivity Class The RelatedActivity class lists either incident tracking numbers of incidents or URLs (not both) that refer to activity related to the one described in the IODEF document. These references may be to local incident tracking numbers or to those of other CSIRTs. The specifics of how a CSIRT comes to believe that two incidents are related are considered out of scope. +------------------+ | RelatedActivity | +------------------+ | ENUM restriction |<>--{1..*}--[ IncidentID ] | |<>--{1..*}--[ URL ] +------------------+ Figure 5: RelatedActivity Class Danyliw & Stoecker Expires March 02, 2014 [Page 16] Internet-Draft IODEF August 2013 The aggregate classes that constitutes RelatedActivity are: IncidentID One or more. The incident tracking number of a related incident. URL One or more. URL. A URL to activity related to this incident. The RelatedActivity class has one attribute: restriction Optional. ENUM. This attribute has been defined in Section 3.2. 3.6. AdditionalData Class The AdditionalData class serves as an extension mechanism for information not otherwise represented in the data model. For relatively simple information, atomic data types (e.g., integers, strings) are provided with a mechanism to annotate their meaning. The class can also be used to extend the data model (and the associated Schema) to support proprietary extensions by encapsulating entire XML documents conforming to another Schema (e.g., IDMEF). A detailed discussion for extending the data model and the schema can be found in Section 5. Unlike XML, which is self-describing, atomic data must be documented to convey its meaning. This information is described in the 'meaning' attribute. Since these description are outside the scope of the specification, some additional coordination may be required to ensure that a recipient of a document using the AdditionalData classes can make sense of the custom extensions. +------------------+ | AdditionalData | +------------------+ | ANY | | | | ENUM dtype | | STRING ext-dtype | | STRING meaning | | STRING formatid | | ENUM restriction | +------------------+ Figure 6: The AdditionalData Class The AdditionalData class has five attributes: Danyliw & Stoecker Expires March 02, 2014 [Page 17] Internet-Draft IODEF August 2013 dtype Required. ENUM. The data type of the element content. The permitted values for this attribute are shown below. The default value is "string". 1. boolean. The element content is of type BOOLEAN. 2. byte. The element content is of type BYTE. 3. character. The element content is of type CHARACTER. 4. date-time. The element content is of type DATETIME. 5. integer. The element content is of type INTEGER. 6. portlist. The element content is of type PORTLIST. 7. real. The element content is of type REAL. 8. string. The element content is of type STRING. 9. file. The element content is a base64 encoded binary file encoded as a BYTE[] type. 10. frame. The element content is a layer-2 frame encoded as a HEXBIN type. 11. packet. The element content is a layer-3 packet encoded as a HEXBIN type. 12. ipv4-packet. The element content is an IPv4 packet encoded as a HEXBIN type. 13. ipv6-packet. The element content is an IPv6 packet encoded as a HEXBIN type. 14. path. The element content is a file-system path encoded as a STRING type. 15. url. The element content is of type URL. 16. csv. The element content is a common separated value (CSV) list per Section 2 of [20] encoded as a STRING type. 17. winreg. The element content is a Windows registry key encoded as a STRING type. 18. xml. The element content is XML (see Section 5). Danyliw & Stoecker Expires March 02, 2014 [Page 18] Internet-Draft IODEF August 2013 19. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-dtype Optional. STRING. A means by which to extend the dtype attribute. See Section 5.1. meaning Optional. STRING. A free-form description of the element content. formatid Optional. STRING. An identifier referencing the format and semantics of the element content. restriction Optional. ENUM. This attribute has been defined in Section 3.2. 3.7. 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 inheriting definition of Contact provides a way to relate information without requiring the explicit use of identifiers in the classes 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. As such, multiple points of contact might be specified in a single instance of a Contact class. Each child Contact class logically inherits contact information from its ancestors. +------------------+ | Contact | +------------------+ | ENUM role |<>--{0..1}--[ ContactName ] | STRING ext-role |<>--{0..*}--[ Description ] | ENUM type |<>--{0..*}--[ RegistryHandle ] | STRING ext-type |<>--{0..1}--[ PostalAddress ] | ENUM restriction |<>--{0..*}--[ Email ] Danyliw & Stoecker Expires March 02, 2014 [Page 19] Internet-Draft IODEF August 2013 | |<>--{0..*}--[ Telephone ] | |<>--{0..1}--[ Fax ] | |<>--{0..1}--[ Timezone ] | |<>--{0..*}--[ Contact ] | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 7: The Contact Class The aggregate classes that constitute the Contact class are: ContactName Zero or one. ML_STRING. The name of the contact. The contact may either be an organization or a person. The type attribute disambiguates the semantics. Description Zero or many. ML_STRING. A free-form description of this contact. In the case of a person, this is often the organizational title of the individual. RegistryHandle Zero or many. A handle name into the registry of the contact. PostalAddress Zero or one. The postal address of the contact. Email Zero or many. The email address of the contact. Telephone Zero or many. The telephone number of the contact. Fax Zero or one. The facsimile telephone number of the contact. Timezone Zero or one. TIMEZONE. The timezone in which the contact resides formatted according to Section 2.9. Contact Zero or many. A Contact instance contained within another Contact instance inherits the values of the parent(s). This recursive 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 Danyliw & Stoecker Expires March 02, 2014 [Page 20] Internet-Draft IODEF August 2013 Zero or many. 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. This is not enforced in the IODEF schema as there is no simple way to accomplish it. The Contact class has five attributes: role Required. ENUM. Indicates the role the contact fulfills. This attribute is defined as an enumerated list: 1. creator. The entity that generate the document. 2. admin. An administrative contact for a host or network. 3. tech. A technical contact for a host or network. 4. irt. The CSIRT involved in handling the incident. 5. cc. An entity that is to be kept informed about the handling of the incident. 6. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-role Optional. STRING. A means by which to extend the role attribute. See Section 5.1. type Required. ENUM. Indicates the type of contact being described. This attribute is defined as an enumerated list: 1. person. The information for this contact references an individual. 2. organization. The information for this contact references an organization. 3. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-type Optional. STRING. A means by which to extend the type attribute. See Section 5.1. restriction Danyliw & Stoecker Expires March 02, 2014 [Page 21] Internet-Draft IODEF August 2013 Optional. ENUM. This attribute is defined in Section 3.2. 3.7.1. RegistryHandle Class The RegistryHandle class represents a handle into an Internet registry or community-specific database. The handle is specified in the element content and the type attribute specifies the database. +---------------------+ | RegistryHandle | +---------------------+ | STRING | | | | ENUM registry | | STRING ext-registry | +---------------------+ Figure 8: The RegistryHandle Class The RegistryHandle class has two attributes: registry Required. ENUM. The database to which the handle belongs. 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 IP Address Registry 5. ripe. Reseaux IP Europeens 6. afrinic. African Internet Numbers Registry 7. local. A database local to the CSIRT 8. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-registry Optional. STRING. A means by which to extend the registry attribute. See Section 5.1. 3.7.2. PostalAddress Class Danyliw & Stoecker Expires March 02, 2014 [Page 22] Internet-Draft IODEF August 2013 The PostalAddress class specifies a postal address formatted according to the POSTAL data type (Section 2.11). +---------------------+ | PostalAddress | +---------------------+ | POSTAL | | | | ENUM meaning | | ENUM lang | +---------------------+ Figure 9: The PostalAddress Class The PostalAddress class has two attributes: meaning Optional. ENUM. A free-form description of the element content. lang Optional. ENUM. A valid language code per RFC 4646 [7] constrained by the definition of "xs:language". The interpretation of this code is described in Section 6. 3.7.3. Email Class The Email class specifies an email address formatted according to EMAIL data type (Section 2.14). +--------------+ | Email | +--------------+ | EMAIL | | | | ENUM meaning | +--------------+ Figure 10: The Email Class The Email class has one attribute: meaning Optional. ENUM. A free-form description of the element content. 3.7.4. Telephone and Fax Classes Danyliw & Stoecker Expires March 02, 2014 [Page 23] Internet-Draft IODEF August 2013 The Telephone and Fax classes specify a voice or fax telephone number respectively, and are formatted according to PHONE data type (Section 2.13). +--------------------+ | {Telephone | Fax } | +--------------------+ | PHONE | | | | ENUM meaning | +--------------------+ Figure 11: The Telephone and Fax Classes The Telephone class has one attribute: meaning Optional. ENUM. A free-form description of the element content (e.g., hours of coverage for a given number). 3.8. Time Classes The data model uses five different classes to represent a timestamp. Their definition is identical, but each has a distinct name to convey a difference in semantics. The element content of each class is a timestamp formatted according to the DATETIME data type (see Section 2.8). +----------------------------------+ | {Start| End| Report| Detect}Time | +----------------------------------+ | DATETIME | +----------------------------------+ Figure 12: The Time Classes 3.8.1. StartTime The StartTime class represents the time the incident began. 3.8.2. EndTime The EndTime class represents the time the incident ended. 3.8.3. DetectTime Danyliw & Stoecker Expires March 02, 2014 [Page 24] Internet-Draft IODEF August 2013 The DetectTime class represents the time the first activity of the incident was detected. 3.8.4. ReportTime The ReportTime class represents the time the incident was reported. This timestamp MUST be the time at which the IODEF document was generated. 3.8.5. DateTime The DateTime class is a generic representation of a timestamp. Infer its semantics from the parent class in which it is aggregated. 3.9. Method Class The Method class describes the methodology used by the intruder to perpetrate the events of the incident. This class consists of a list of references describing the attack method and a free form description of the technique. +------------------+ | Method | +------------------+ | ENUM restriction |<>--{0..*}--[ Reference ] | |<>--{0..*}--[ Description ] | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 13: The Method Class The Method class is composed of three aggregate classes. Reference Zero or many. A reference to a vulnerability, malware sample, advisory, or analysis of an attack technique. Description Zero or many. ML_STRING. A free-form text description of the methodology used by the intruder. AdditionalData Zero or many. A mechanism by which to extend the data model. Either an instance of the Reference or Description class MUST be present. The Method class has one attribute: Danyliw & Stoecker Expires March 02, 2014 [Page 25] Internet-Draft IODEF August 2013 restriction Optional. ENUM. This attribute is defined in Section 3.2. 3.9.1. Reference Class The Reference class is a reference to a vulnerability, IDS alert, malware sample, advisory, or attack technique. A reference consists of a name, a URL to this reference, and an optional description. +------------------+ | Reference | +------------------+ | |<>----------[ ReferenceName ] | |<>--{0..*}--[ URL ] | |<>--{0..*}--[ Description ] +------------------+ Figure 14: The Reference Class The aggregate classes that constitute Reference: ReferenceName One. ML_STRING. Name of the reference. URL Zero or many. URL. A URL associated with the reference. Description Zero or many. ML_STRING. A free-form text description of this reference. The Reference class has 4 attributes. indicator-uid Optional. STRING. A unique identifier for an Indicator. indicator-set-id Optional. STRING. The indicator set ID is used to group releated indicators. attacktype Optional. ENUM. A unique identifier for an Indicator. ext-attacktype Optional. STRING. A mechanism by which to extend the Attack Type. Danyliw & Stoecker Expires March 02, 2014 [Page 26] Internet-Draft IODEF August 2013 3.10. Assessment Class The Assessment class describes the technical and non-technical repercussions of the incident on the CSIRT's constituency. This class was derived from the IDMEF[17]. +------------------+ | Assessment | +------------------+ | ENUM occurrence |<>--{0..*}--[ Impact ] | ENUM restriction |<>--{0..*}--[ TimeImpact ] | |<>--{0..*}--[ MonetaryImpact ] | |<>--{0..*}--[ Counter ] | |<>--{0..1}--[ Confidence ] | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 15: Assessment Class The aggregate classes that constitute Assessment are: Impact Zero or many. Technical impact of the incident on a network. TimeImpact Zero or many. Impact of the activity measured with respect to time. MonetaryImpact Zero or many. Impact of the activity measured with respect to financial loss. Counter Zero or more. A counter with which to summarize the magnitude of the activity. Confidence Zero or one. An estimate of confidence in the assessment. AdditionalData Zero or many. A mechanism by which to extend the data model. A least one instance of the possible three impact classes (i.e., Impact, TimeImpact, or MonetaryImpact) MUST be present. The Assessment class has four attributes: Danyliw & Stoecker Expires March 02, 2014 [Page 27] Internet-Draft IODEF August 2013 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. This attribute is defined in Section 3.2. indicator-uid Optional. STRING. A unique identifier for an Indicator. indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. 3.10.1. Impact Class The Impact class allows for categorizing and describing the technical impact of the incident on the network of an organization. This class is based on the IDMEF [17]. +------------------+ | Impact | +------------------+ | ML_STRING | | | | ENUM lang | | ENUM severity | | ENUM completion | | ENUM type | | STRING ext-type | +------------------+ Figure 16: Impact Class The element content will be a free-form textual description of the impact. The Impact class has five attributes: lang Danyliw & Stoecker Expires March 02, 2014 [Page 28] Internet-Draft IODEF August 2013 Optional. ENUM. A valid language code per RFC 4646 [7] constrained by the definition of "xs:language". The interpretation of this code is described in Section 6. 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 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 malicious activity into incident categories. The permitted values are shown below. The default value is "other". 1. admin. Administrative privileges were attempted. 2. dos. A denial of service was attempted. 3. file. An action that impacts the integrity of a file or database was attempted. 4. info-leak. An attempt was made to exfiltrate information. 5. misconfiguration. An attempt was made to exploit a mis- configuration in a system. 6. policy. Activity violating site's policy was attempted. 7. recon. Reconnaissance activity was attempted. 8. social-engineering. A social engineering attack was attempted. Danyliw & Stoecker Expires March 02, 2014 [Page 29] Internet-Draft IODEF August 2013 9. user. User privileges were attempted. 10. unknown. The classification of this activity is unknown. 11. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-type Optional. STRING. A means by which to extend the type attribute. See Section 5.1. 3.10.2. 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 17: TimeImpact Class The element content is a positive, floating point (REAL) number specifying a unit of time. The duration and metric attributes will imply the semantics of the element content. The TimeImpact class has five attributes: 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 & Stoecker Expires March 02, 2014 [Page 30] Internet-Draft IODEF August 2013 metric Required. ENUM. Defines the metric in which the time is expressed. The permitted values are shown below. There is no default value. 1. labor. Total staff-time to recovery from the activity (e.g., 2 employees working 4 hours each would be 8 hours). 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. An escape value used to extend this attribute. See Section 5.1. ext-metric Optional. STRING. A means by which to extend the metric attribute. See Section 5.1. duration Optional. ENUM. Defines a unit of time, that when combined with the metric attribute, fully describes a metric of impact that will be conveyed in the element content. The permitted values are shown below. The default value is "hour". 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. An escape value used to extend this attribute. See Section 5.1. ext-duration Optional. STRING. A means by which to extend the duration attribute. See Section 5.1. Danyliw & Stoecker Expires March 02, 2014 [Page 31] Internet-Draft IODEF August 2013 3.10.3. 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 18: MonetaryImpact Class The element content is a positive, floating point number (REAL) specifying a unit of currency described in the currency attribute. The MonetaryImpact class has two attributes: 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 monetary impact is expressed. The permitted values are defined in ISO 4217:2001, Codes for the representation of currencies and funds [14]. There is no default value. 3.10.4. Confidence Class The Confidence class represents a best estimate of the validity and accuracy of the described impact (see Section 3.10) of the incident activity. This estimate can be expressed as a category or a numeric calculation. Danyliw & Stoecker Expires March 02, 2014 [Page 32] Internet-Draft IODEF August 2013 This class if based upon the IDMEF [17]). +------------------+ | Confidence | +------------------+ | REAL | | | | ENUM rating | +------------------+ Figure 19: Confidence Class The element content expresses 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 Confidence class has one attribute. rating Required. ENUM. A rating of the analytical validity of the specified Assessment. The permitted values are shown below. There is no default value. 1. low. Low confidence in the validity. 2. medium. Medium confidence in the validity. 3. high. High confidence in the validity. 4. numeric. The element content contains a number that conveys the confidence of the data. The semantics of this number outside the scope of this specification. 5. unknown. The confidence rating value is not known. 3.11. 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 | +------------------+ Danyliw & Stoecker Expires March 02, 2014 [Page 33] Internet-Draft IODEF August 2013 | ENUM restriction |<>--{1..*}--[ HistoryItem ] | | +------------------+ Figure 20: The History Class The class that constitutes History is: HistoryItem One or many. Entry in the history log of significant events or actions performed by the involved parties. The History class has one attribute: restriction Optional. ENUM. This attribute is defined in Section 3.2. The default value is "default". 3.11.1. HistoryItem Class The HistoryItem class is an entry in the History (Section 3.11) 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 description, but each can be categorized with the type attribute. +-------------------+ | HistoryItem | +-------------------+ | ENUM restriction |<>----------[ DateTime ] | ENUM action |<>--{0..1}--[ IncidentId ] | STRING ext-action |<>--{0..1}--[ Contact ] | |<>--{0..*}--[ Description ] | |<>--{0..*}--[ AdditionalData ] +-------------------+ Figure 21: HistoryItem Class The aggregate classes that constitute HistoryItem are: DateTime One. Timestamp of this entry in the history log (e.g., when the action described in the Description was taken). 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 incident Danyliw & Stoecker Expires March 02, 2014 [Page 34] Internet-Draft IODEF August 2013 tracking number. When a single organization is maintaining the log, this class can be ignored. Contact Zero or One. Provides contact information for the person that performed the action documented in this class. Description Zero or many. ML_STRING. A free-form textual description of the action or event. AdditionalData Zero or many. A mechanism by which to extend the data model. The HistoryItem class has five attributes: restriction Optional. ENUM. This attribute has been defined in Section 3.2. 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 internal investigation, this attribute is identical to the category 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 3.13. ext-action Optional. STRING. A means by which to extend the action attribute. See Section 5.1. indicator-uid Optional. STRING. A unique identifier for an Indicator. indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. 3.12. EventData Class The EventData class describes a particular event of the incident for a given set of hosts or networks. This description includes the systems from which the activity originated and those targeted, an assessment of the techniques used by the intruder, the impact of the activity on the organization, and any forensic evidence discovered. Danyliw & Stoecker Expires March 02, 2014 [Page 35] Internet-Draft IODEF August 2013 +------------------+ | EventData | +------------------+ | ENUM restriction |<>--{0..*}--[ Description ] | |<>--{0..1}--[ DetectTime ] | |<>--{0..1}--[ StartTime ] | |<>--{0..1}--[ EndTime ] | |<>--{0..*}--[ Contact ] | |<>--{0..1}--[ Assessment ] | |<>--{0..*}--[ Method ] | |<>--{0..*}--[ Flow ] | |<>--{0..*}--[ Expectation ] | |<>--{0..1}--[ Record ] | |<>--{0..*}--[ EventData ] | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 22: The EventData Class The aggregate classes that constitute EventData are: Description Zero or more. ML_STRING. A free-form textual description of the event. DetectTime Zero or one. The time the event was detected. StartTime Zero or one. The time the event started. EndTime Zero or one. The time the event ended. Contact Zero or more. Contact information for the parties involved in the event. Assessment Zero or one. The impact of the event on the target and the actions taken. Method Zero or more. The technique used by the intruder in the event. Flow Zero or more. A description of the systems or networks involved. Danyliw & Stoecker Expires March 02, 2014 [Page 36] Internet-Draft IODEF August 2013 Expectation Zero or more. The expected action to be performed by the recipient for the described event. Record Zero or one. Supportive data (e.g., log files) that provides additional information about the event. EventData Zero or more. EventData instances contained within another EventData instance inherit the values of the parent(s); this recursive definition can be used to group common data pertaining to multiple events. When EventData elements are defined recursively, only the leaf instances (those EventData instances not containing other EventData instances) represent actual events. AdditionalData Zero or more. 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. This is not enforced in the IODEF schema as there is no simple way to accomplish it. The EventData class has two attributes: restriction Optional. ENUM. This attribute is defined in Section 3.2. The default value is "default". indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. 3.12.1. Relating the Incident and EventData Classes Danyliw & Stoecker Expires March 02, 2014 [Page 37] Internet-Draft IODEF August 2013 There is substantial overlap 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 most common case, the EventData class will provide more specific information for the general description provided in the Incident class. However, it may also be possible that the overall summarized information about the incident conflicts with some individual information in an EventData class when there is a substantial composition of various events in the incident. In such a case, the interpretation of the more specific EventData MUST supersede the more generic information provided in IncidentData. 3.12.2. Cardinality of EventData The EventData class can be thought of as 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. With an instance of the EventData class, hosts (i.e., System class) are grouped around these common properties. The recursive definition (or instance property inheritance) of the EventData class (the EventData class is aggregated into the EventData class) provides a way to related information without requiring the explicit use of unique attribute identifiers in the classes or duplicating information. Instead, the relative depth (nesting) of a class is used to group (relate) information. For example, an EventData class might be used to describe two machines involved in an incident. This description can be achieved using multiple instances of the Flow class. It happens that there is a common technical contact (i.e., Contact class) for these two machines, but the impact (i.e., Assessment class) on them is different. A depiction of the representation for this situation can be found in Figure 23. +------------------+ | EventData | +------------------+ | |<>----[ Contact ] | | | |<>----[ EventData ]<>----[ Flow ] | | [ ]<>----[ Assessment ] | | | |<>----[ EventData ]<>----[ Flow ] | | [ ]<>----[ Assessment ] +------------------+ Danyliw & Stoecker Expires March 02, 2014 [Page 38] Internet-Draft IODEF August 2013 Figure 23: Recursion in the EventData Class 3.13. Expectation Class The Expectation class conveys to the recipient of the IODEF document the actions the sender is requesting. The scope of the requested action is limited to purview of the EventData class in which this class is aggregated. +-------------------+ | Expectation | +-------------------+ | ENUM restriction |<>--{0..*}--[ Description ] | ENUM severity |<>--{0..1}--[ StartTime ] | ENUM action |<>--{0..1}--[ EndTime ] | STRING ext-action |<>--{0..1}--[ Contact ] +-------------------+ Figure 24: The Expectation Class The aggregate classes that constitute Expectation are: Description Zero or many. ML_STRING. A free-form description of the desired action(s). StartTime Zero or one. 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 expections of when the recipient would like the action performed. EndTime Zero or one. The time by which the sensor 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, clock drift, and so on, 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 expected actor for the action. The Expectations class has six attributes: restriction Danyliw & Stoecker Expires March 02, 2014 [Page 39] Internet-Draft IODEF August 2013 Optional. ENUM. This attribute is defined in Section 3.2. The default value is "default". 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 dependant. 1. low. Low priority 2. medium. Medium priority 3. high. High priority action Optional. ENUM. Classifies the type of action requested. This attribute is an enumerated list with a default value of "other". 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 systems(s) listed in the event. 6. block-host. Block traffic from the machine(s) listed as sources 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. 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. Danyliw & Stoecker Expires March 02, 2014 [Page 40] Internet-Draft IODEF August 2013 12. remediate-other. Remediate the activity in a way other than by rate limiting or blocking. 13. status-triage. Conveys receipts and the triaging of an incident. 14. status-new-info. Conveys that new information was received for this incident. 15. watch-and-report. Watch for the described activity and share if seen. 16. other. Perform some custom action described in the Description class. 17. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-action Optional. STRING. A means by which to extend the action attribute. See Section 5.1. indicator-uid Optional. STRING. A unique identifier for an Indicator. indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. 3.14. Flow Class The Flow class groups related the source and target hosts. +------------------+ | Flow | +------------------+ | |<>--{1..*}--[ System ] +------------------+ Figure 25: The Flow Class The aggregate class that constitutes Flow is: System One or More. A host or network involved in an event. The Flow System class has no attributes. Danyliw & Stoecker Expires March 02, 2014 [Page 41] Internet-Draft IODEF August 2013 3.15. System Class The System class describes a system or network involved in an event. The systems or networks represented by this class are categorized according to the role they played in the incident through the category attribute. The value of this category attribute dictates the semantics of the aggregated classes in the System class. If the category attribute has a value of "source", then the aggregated classes denote the machine and service from which the activity is originating. With a category attribute value of "target" or "intermediary", then the machine or service is the one targeted in the activity. A value of "sensor" dictates that this System was part of an instrumentation to monitor the network. +---------------------+ | System | +---------------------+ | ENUM restriction |<>----------[ Node ] | ENUM category |<>--{0..*}--[ Service ] | STRING ext-category |<>--{0..*}--[ OperatingSystem ] | STRING interface |<>--{0..*}--[ Counter ] | ENUM spoofed |<>--{0..*}--[ Description ] | |<>--{0..*}--[ AdditionalData ] +---------------------+ Figure 26: The System Class The aggregate classes that constitute System are: Node One. A host or network involved in the incident. Service Zero or more. A network service running on the system. OperatingSystem Zero or more. The operating system running on the system. Counter Zero or more. A counter with which to summarize properties of this host or network. Description Zero or more. ML_STRING. A free-form text description of the System. AdditionalData Zero or many. A mechanism by which to extend the data model. Danyliw & Stoecker Expires March 02, 2014 [Page 42] Internet-Draft IODEF August 2013 The System class has six attributes: restriction Optional. ENUM. This attribute is defined in Section 3.2. category Optional. ENUM. Classifies the role the host or network played in the incident. The possible values are: 1. source. The System was the source of the event. 2. target. The System was the target of the event. 3. watchlist-source. The source of the event was on a watchlist. 4. watchlist-target. The target of the event was on a watchlist. 5. intermediate. The System was an intermediary in the event. 6. sensor. The System was a sensor monitoring the event. 7. infrastructure. The System was an infrastructure node of IODEF document exchange. 8. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-category Optional. STRING. A means by which to extend the category attribute. See Section 5.1. indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. 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 & Stoecker Expires March 02, 2014 [Page 43] Internet-Draft IODEF August 2013 2. yes. The category attribute value is probably 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. 3.16. Node Class The Node class names a system (e.g., PC, router) or network. This class was derived from the IDMEF [17]. +---------------+ | Node | +---------------+ | |<>--{0..*}--[ NodeName ] | |<>--{0..*}--[ DomainData ] | |<>--{0..*}--[ Address ] | |<>--{0..1}--[ Location ] | |<>--{0..1}--[ DateTime ] | |<>--{0..*}--[ NodeRole ] | |<>--{0..*}--[ Counter ] +---------------+ Figure 27: The Node Class The aggregate classes that constitute Node are: NodeName Zero or more. ML_STRING. The name of the Node (e.g., fully qualified domain name). This information MUST be provided if no Address information is given. DomainData Zero or more. The DomainData Class and Subclasses from RFC 5901. Address Zero or more. The hardware, network, or application address of the Node. If a NodeName is not provided, at least one Address MUST be specified. Location Zero or one. ML_STRING. A free-from description of the physical location of the equipment. DateTime Danyliw & Stoecker Expires March 02, 2014 [Page 44] Internet-Draft IODEF August 2013 Zero or one. A timestamp of when the resolution between the name and address was performed. This information MAY be provided if both an Address and NodeName are specified. NodeRole Zero or more. The intended purpose of the Node. Counter Zero or more. A counter with which to summarizes properties of this host or network. 3.16.1. Counter Class The Counter class summarize multiple occurrences of some event, or conveys counts or rates on various features (e.g., packets, sessions, events). The value of the counter is the element content with its units represented in the type attribute. A rate for a given feature can be expressed by setting the duration attribute. The complete semantics are entirely context dependant based on the class in which the Counter is aggregated. +---------------------+ | Counter | +---------------------+ | REAL | | | | ENUM type | | STRING ext-type | | STRING meaning | | ENUM duration | | STRING ext-duration | +---------------------+ Figure 28: The Counter Class The Counter class has three attribute: type Required. ENUM. Specifies the units of the element content. 1. byte. Count of bytes. 2. packet. Count of packets. 3. flow. Count of flow (e.g., NetFlow records). Danyliw & Stoecker Expires March 02, 2014 [Page 45] Internet-Draft IODEF August 2013 4. session. Count of sessions. 5. alert. Count of notifications generated by another system (e.g., IDS or SIM). 6. message. Count of messages (e.g., mail messages). 7. event. Count of events. 8. host. Count of hosts. 9. site. Count of site. 10. organization. Count of organizations. 11. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-type Optional. STRING. A means by which to extend the type attribute. See Section 5.1. duration Optional. ENUM. If present, the Counter class represents a rate rather than a count over the entire event. In that case, this attribute specifies the denominator of the rate (where the type attribute specified the nominator). The possible values of this attribute are defined in Section 3.10.2 ext-duration Optional. STRING. A means by which to extend the duration attribute. See Section 5.1. 3.16.2. Address Class The Address class represents a hardware (layer-2), network (layer-3), or application (layer-7) address. This class was derived from the IDMEF [17]. +---------------------+ | Address | +---------------------+ | ENUM category | | STRING ext-category | | STRING vlan-name | | INTEGER vlan-num | +---------------------+ Danyliw & Stoecker Expires March 02, 2014 [Page 46] Internet-Draft IODEF August 2013 Figure 29: The Address Class The Address class has five attributes: category Optional. ENUM. The type of address represented. The permitted values for this attribute are shown below. The default value is "ipv4-addr". 1. asn. Autonomous System Number 2. atm. Asynchronous Transfer Mode (ATM) address 3. e-mail. Electronic mail address (RFC 822) 4. ipv4-addr. IPv4 host address in dotted-decimal notation (a.b.c.d) 5. ipv4-net. IPv4 network address in dotted-decimal notation, slash, significant bits (a.b.c.d/nn) 6. ipv4-net-mask. IPv4 network address in dotted-decimal notation, slash, network mask in dotted-decimal notation (a.b.c.d/w.x.y.z) 7. ipv6-addr. IPv6 host address 8. ipv6-net. IPv6 network address, slash, significant bits 9. ipv6-net-mask. IPv6 network address, slash, network mask 10. mac. Media Access Control (MAC) address 11. site-uri. A URL or URI for a site. 12. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-category Optional. STRING. A means by which to extend the category attribute. See Section 5.1. vlan-name Optional. STRING. The name of the Virtual LAN to which the address belongs. vlan-num Danyliw & Stoecker Expires March 02, 2014 [Page 47] Internet-Draft IODEF August 2013 Optional. STRING. The number of the Virtual LAN to which the address belongs. indicator-uid Optional. STRING. A unique identifier for an Indicator. 3.16.3. NodeRole Class The NodeRole class describes the intended function performed by a particular host. +---------------------+ | NodeRole | +---------------------+ | ENUM category | | STRING ext-category | | ENUM lang | +---------------------+ Figure 30: The NodeRole Class The NodeRole class has three attributes: category Required. ENUM. Functionality provided by a node. 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 is serves as a kiosk 6. client-mobile. Client is a 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. messaging. Messaging server (e.g., NNTP, IRC, IM) Danyliw & Stoecker Expires March 02, 2014 [Page 48] Internet-Draft IODEF August 2013 12. streaming. Streaming-media server 13. voice. Voice server (e.g., SIP, H.323) 14. file. File server (e.g., SMB, CVS, AFS) 15. ftp. FTP server 16. p2p. Peer-to-peer node 17. name. Name server (e.g., DNS, WINS) 18. directory. Directory server (e.g., LDAP, finger, whois) 19. credential. Credential server (e.g., domain controller, Kerberos) 20. print. Print server 21. application. Application server 22. database. Database server 23. backup. Backup server 24. dhcp. DHCP server 25. infra. Infrastructure server (e.g., router, firewall, DHCP) 26. infra-firewall. Firewall 27. infra-router. Router 28. infra-switch. Switch 29. camera. Camera server 30. proxy. Proxy server 31. remote-access. Remote access server 32. log. Logserver (e.g., syslog) 33. virtualization. Server running virtual machines 34. pos. Point-of-sale device 35. scada. Supervisory control and data acquisition system Danyliw & Stoecker Expires March 02, 2014 [Page 49] Internet-Draft IODEF August 2013 36. scada-supervisory. Supervisory system for a SCADA 37. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-category Optional. STRING. A means by which to extend the category attribute. See Section 5.1. lang Optional. ENUM. A valid language code per RFC 4646 [7] constrained by the definition of "xs:language". The interpretation of this code is described in Section 6. 3.17. Service Class The Service class describes a network service of a host or network. The service is identified by specific port or list of ports, along with the application listening on that port. When Service occurs as an aggregate class of a System that is a source, then this service is the one from which activity of interest is originating. Conversely, when Service occurs as an aggregate class of a System that is a target, then that service is the one to which activity of interest is directed. This class was derived from the IDMEF [17]. +---------------------+ | Service | +---------------------+ | INTEGER ip_protocol |<>--{0..1}--[ Port ] | |<>--{0..1}--[ Portlist ] | |<>--{0..1}--[ ProtoCode ] | |<>--{0..1}--[ ProtoType ] | |<>--{0..1}--[ ProtoField ] | |<>--{0..1}--[ Application ] +---------------------+ Figure 31: The Service Class The aggregate classes that constitute Service are: Port Zero or one. INTEGER. A port number. Portlist Danyliw & Stoecker Expires March 02, 2014 [Page 50] Internet-Draft IODEF August 2013 Zero or one. PORTLIST. A list of port numbers formatted according to Section 2.10. ProtoCode Zero or one. INTEGER. A layer-4 protocol-specific code field (e.g., ICMP code field). ProtoType Zero or one. INTEGER. A layer-4 protocol specific type field (e.g., ICMP type field). ProtoField Zero or one. INTEGER. A layer-4 protocol specific flag field (e.g., TCP flag field). Application Zero or one. The application bound to the specified Port or Portlist. Either a Port or Portlist class MUST be specified for a given instance of a Service class. When a given System classes 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 Porlists 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 a Flow class MUST only have a single instance of a System@category="source" and System@category="target". The Service class has three attributes: ip_protocol Required. INTEGER. The IANA protocol number. indicator-uid Optional. STRING. A unique identifier for an Indicator. indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. 3.17.1. Application Class Danyliw & Stoecker Expires March 02, 2014 [Page 51] Internet-Draft IODEF August 2013 The Application class describes an application running on a System providing a Service. +--------------------+ | Application | +--------------------+ | STRING swid |<>--{0..1}--[ URL ] | STRING configid | | STRING vendor | | STRING family | | STRING name | | STRING version | | STRING patch | +--------------------+ Figure 32: The Application Class The aggregate class that constitute Application is: URL Zero or one. URL. A URL describing the application. The Application class has seven attributes: swid Optional. STRING. An identifier that can be used to reference this software, where the default value is "0". configid Optional. STRING. An identifier that can be used to reference a particular configuration of this software, where the default value is "0". vendor Optional. STRING. Vendor name of the software. family Optional. STRING. Family of the software. name Optional. STRING. Name of the software. version Optional. STRING. Version of the software. patch Optional. STRING. Patch or service pack level of the software. Danyliw & Stoecker Expires March 02, 2014 [Page 52] Internet-Draft IODEF August 2013 3.18. OperatingSystem Class The OperatingSystem class describes the operating system running on a System. The definition is identical to the Application class (Section 3.17.1). 3.19. Record Class The Record class is a container class for log and audit data that provides supportive information about the 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 ] +------------------+ Figure 33: Record Class The aggregate class that constitutes Record is: RecordData One or more. Log or audit data generated by a particular type of sensor. Separate instances of the RecordData class SHOULD be used for each sensor type. The Record class has one attribute: restriction Optional. ENUM. This attribute has been defined in Section 3.2. 3.19.1. RecordData Class The RecordData class groups log or audit data from a given sensor (e.g., IDS, firewall log) and provides a way to annotate the output. +------------------+ | RecordData | +------------------+ | ENUM restriction |<>--{0..1}--[ DateTime ] | |<>--{0..*}--[ Description ] | |<>--{0..1}--[ Application ] | |<>--{0..*}--[ RecordPattern ] | |<>--{0..*}--[ RecordItem ] | |<>--{0..1}--[ HashInformation ] | |<>--{0..*}--[ WindowsRegistryKeysModified ] Danyliw & Stoecker Expires March 02, 2014 [Page 53] Internet-Draft IODEF August 2013 | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 34: The RecordData Class The aggregate classes that constitutes RecordData is: DateTime Zero or one. Timestamp of the RecordItem data. Description Zero or more. ML_STRING. Free-form textual description of the provided RecordItem data. At minimum, this description should convey the significance of the provided RecordItem data. Application Zero or one. Information about the sensor used to generate the RecordItem data. RecordPattern Zero or more. A search string to precisely find the relevant data in a RecordItem. RecordItem Zero or more. Log, audit, or forensic data. HashInformation Zero or one. The file name and hash of a file indicator. WindowsRegistryKeysModified Zero or more. The registry keys that were modified that are indicator(s). AdditionalData Zero or more. An extension mechanism for data not explicitly represented in the data model. The RecordData class has three attribute: restriction Optional. ENUM. This attribute has been defined in Section 3.2. indicator-uid Optional. STRING. A unique identifier for an Indicator. indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. Danyliw & Stoecker Expires March 02, 2014 [Page 54] Internet-Draft IODEF August 2013 3.19.2. RecordPattern Class The RecordPattern class describes where in the content of the RecordItem 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. +-----------------------+ | RecordPattern | +-----------------------+ | STRING | | | | ENUM type | | STRING ext-type | | INTEGER offset | | ENUM offsetunit | | STRING ext-offsetunit | | INTEGER instance | +-----------------------+ Figure 35: The RecordPattern Class The specific pattern to search with in the RecordItem is defined in the body of the element. It is further annotated by four attributes: type Required. ENUM. Describes the type of pattern being specified in the element content. The default is "regex". 1. regex. regular expression, per Appendix F of [3]. 2. binary. Binhex encoded binary pattern, per the HEXBIN data type. 3. xpath. XML Path (XPath) [5] 4. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-type Optional. STRING. A means by which to extend the type attribute. See Section 5.1. offset Optional. INTEGER. Amount of units (determined by the offsetunit attribute) to seek into the RecordItem data before matching the pattern. Danyliw & Stoecker Expires March 02, 2014 [Page 55] Internet-Draft IODEF August 2013 offsetunit Optional. ENUM. Describes the units of the offset attribute. The default is "line". 1. line. Offset is a count of lines. 2. byte. Offset is a count of bytes. 3. ext-value. An escape value used to extend this attribute. See Section 5.1. ext-offsetunit Optional. STRING. A means by which to extend the offsetunit attribute. See Section 5.1. instance Optional. INTEGER. Number of types to apply the specified pattern. 3.19.3. RecordItem Class The RecordItem class provides a way to incorporate relevant logs, audit trails, or forensic data to support the conclusions made during the course of analyzing the incident. The class supports both the direct encapsulation of the data, as well as, provides primitives to reference data stored elsewhere. This class is identical to AdditionalData class (Section 3.6). 3.20. RegistryKeyModified Class The Registry Key Modified class represents operating system registry keys that have been modified as part and may constitue an indicator of compromise. +-----------------------+ | RegistryKeyModified | +-----------------------+ | |<>----------[ Key ] +-----------------------+ Figure 36: The RegistryKeyModified Class The aggregate class that constitutes the Registry Key Modified class is: Key One. The Window Registry Key. Danyliw & Stoecker Expires March 02, 2014 [Page 56] Internet-Draft IODEF August 2013 3.20.1. Key Class The Key class shows name and value pairs representing an operating system registry key and its value. The key and value are encoded as in Microsoft .reg files. +--------------------------+ | Key | +--------------------------+ | ENUM regsitryaction |<>--{0..*}--[ KeyName ] | STRING ext-category |<>--{0..*}--[ Value ] | ENUM type | | STRING ext-type | | STRING indicator-uid | | STRING inidicator-set-id | +--------------------------+ Figure 37: The Registry Key Modified Class The aggregate classes that constitutes Key are: KeyName Zero or more. The name of the registry key. Value Zero or more. The value of the registry key. The Key class has six attributes: registryaction Optional. ENUM. The type of action. 1. add-key. Registry key added. 2. add-value. Value added to registry key. 3. delete-key. Registry key deleted. 4. delete-value. Value deleted from registry key. 5. modify-key. Registry key modified. 6. modify-value. Value modified for registry key. 7. ext-value. External value. ext-category Optional. Extension category. Danyliw & Stoecker Expires March 02, 2014 [Page 57] Internet-Draft IODEF August 2013 type Optional. Type 1. watchlist. Registry key information that is provided in a watchlist. 2. ext-value. Registry key information from an external source. indicator-uid Optional. STRING. A unique identifier for an Indicator. indicator-set-id Optional. STRING. The indicator set ID is used to group relfated indicators. 3.21. HashInformation Class This class are the hash and signature details that are needed for providing context for indicators. +--------------------------+ | HashInformation | +--------------------------+ | ENUM type |<>--{0..*}--[ FileName ] | STRING ext-category |<>--{0..*}--[ FileSize ] | BOOL valid |<>--{0..*}--[ ds:Signature ] | STRING indicator-uid |<>--{0..*}--[ ds:KeyInfo ] | STRING inidicator-set-id |<>--{0..*}--[ ds:Reference ] +--------------------------+ Figure 38: The Hash Sig Details Class The aggregate classes that constitutes HashInformation are: FileName Zero or more. ML_STRING. The name of the file. FileSize Zero or more. INTEGER. The size of the file in bytes. ds:Signature Zero or more. ds:KeyInfo Zero or more. ds:Reference Danyliw & Stoecker Expires March 02, 2014 [Page 58] Internet-Draft IODEF August 2013 Zero or more. The algorithm identification and value of a hash computed over the malware executable. This entire element is imported from [RFC3275]. Refer to RFC 5901. The HashInformation class has five attributes: type Optional. ENUM. The Hash Type. 1. PKI-email-ds. PKI email digital signature. 2. PKI-file-ds. PKI file digital signature. 3. PKI-email-ds_watchlist. Watchlist of PKI email digital signatures. 4. PKI-file-ds_watchlist. Watchlist of PKI file digital signatures. 5. PGP-email-ds. PGP email digital signature. 6. PGP-file-ds. PGP file digital signature. 7. PGP-email-ds-watchlist. Watchlist of PGP email digital signatures. 8. PGP-file-ds-watchlist. Watchlist of PGP file digital signatures 9. file-hash. A file hash. 10. email-hash. An email hash. 11. file-hash-watchlist. Watchlist of file hashes 12. email-hash-watchlist. Watchlist of email hashes 13. ext-value. Extension value. indicator-uid Optional. STRING. A unique identifier for an Indicator. indicator-set-id Optional. STRING. The indicator set ID is used to group related indicators. 4. Processing Considerations Danyliw & Stoecker Expires March 02, 2014 [Page 59] Internet-Draft IODEF August 2013 This section defines additional requirements on creating and parsing IODEF documents. 4.1. Encoding Every IODEF document MUST begin with an XML declaration, and MUST specify the XML version used. If UTF-8 encoding is not used, the character encoding MUST also be explicitly specified. The IODEF conforms to all XML data encoding conventions and constraints. The XML declaration with no character encoding will read as follows: When a character encoding is specified, the XML declaration will read like the following: Where "charset" is the name of the character encoding as registered with the Internet Assigned Numbers Authority (IANA), see [9]. The following characters have special meaning in XML and MUST be escaped with their entity reference equivalent: "&", "<", ">", "\"" (double quotation mark), and "'" (apostrophe). These entity references are "&", "<", ">", """, and "'" respectively. 4.2. IODEF Namespace The IODEF schema declares a namespace of "urn:ietf:params:xml:ns:iodef-1.0" and registers it per [4]. 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: A given extension attribute MUST NOT be set unless the corresponding extensible attribute has been set to "ext-value". 5.2. Extending Classes The classes of the data model can be extended only through the use of the AdditionalData and RecordItem classes. These container classes, collectively referred to as the extensible classes, are implemented with the iodef:ExtensionType data type in the schema. 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 a few of the more complicated 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. Danyliw & Stoecker Expires March 02, 2014 [Page 62] Internet-Draft IODEF August 2013 Extensions using the atomic data types (i.e., all values of the dtype attributes other than "xml") MUST: 1. Set the element content of extensible class to the desired value, and 2. Set the dtype attribute to correspond to the data type of the element content. The following guidelines exist for extensions using 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 makes reading an extended IODEF document look like any other IODEF document. The names of all elements are capitalized. For elements with composed names, a capital letter is used for each word. Attribute names are lower case. Attributes with composed names are seperated by a hyphen. 4. Parsers that encounter an unrecognized element in a namespace that they do support MUST reject the document as a syntax error. 5. There are security and performance implications in requiring implementations to dynamically download schemas at run time. Thus, implementations SHOULD NOT download schemas at runtime, unless implementations take appropriate precautions and are prepared for potentially significant network, processing, and time-out demands. 6. Some users of the IODEF may have private schema definitions that might not be available on the Internet. In this situation, if a IODEF document leaks out of the private use space, references to some of those document schemas may not be resolvable. This has two implications. First, references to private schemas may never resolve. As such, in addition to the suggestion that implementations do not download schemas at runtime mentioned above, recipients MUST be prepared for a schema definition in an IODEF document never to resolve. Danyliw & Stoecker Expires March 02, 2014 [Page 63] Internet-Draft IODEF August 2013 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". attributeFormDefault="unqualified" elementFormDefault="qualified"> The following XML excerpt demonstrates the use of the above schema as an extension to the IODEF. ... Field that could not be represented elsewhere 189493 2001-09-13T23:19:24+00:00 Host sending out Code Red probes Example.com CSIRT example-com contact@csirt.example.com
192.0.2.200
57
192.0.2.16/28
80
2001-09-13T18:11:21+02:00 Web-server logs 192.0.2.1 - - [13/Sep/2001:18:11:21 +0200] "GET /default.ida? XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX http://mylogs.example.com/logs/httpd_access Danyliw & Stoecker Expires March 02, 2014 [Page 66] Internet-Draft IODEF August 2013
2001-09-14T08:19:01+00:00 Notification sent to constituency-contact@192.0.2.200
7.2. Reconnaissance An example of a CSIRT reporting a scanning activity. 59334 2006-08-02T05:54:02-05:00 nmap http://nmap.toolsite.example.com CSIRT for example.com contact@csirt.example.com +1 412 555 12345 Joe Smith smith@csirt.example.com
192.0.2.200
60524,60526,60527,60531
192.0.2.201
137-139,445
192.0.2.240
192.0.2.64/28
445
Danyliw & Stoecker Expires March 02, 2014 [Page 68] Internet-Draft IODEF August 2013
7.3. Bot-Net Reporting An example of a CSIRT reporting a bot-network. 908711 2006-06-08T05:44:53-05:00 Large bot-net GT Bot CA-2003-22 http://www.cert.org/advisories/CA-2003-22.html Root compromise via this IE vulnerability to install the GT Bot Joe Smith jsmith@csirt.example.com These hosts are compromised and acting as bots communicating with irc.example.com. Danyliw & Stoecker Expires March 02, 2014 [Page 69] Internet-Draft IODEF August 2013
192.0.2.1
10000 bot
192.0.2.3
250000 bot
irc.example.com
192.0.2.20
2006-06-08T01:01:03-05:00
IRC server on #give-me-cmd channel
Confirm the source and take machines off-line and remediate
Danyliw & Stoecker Expires March 02, 2014 [Page 70] Internet-Draft IODEF August 2013 7.4. Watch List An example of a CSIRT conveying a watch-list. 908711 2006-08-01T00:00:00-05:00 Watch-list of known bad IPs or networks CSIRT for example.com contact@csirt.example.com
192.0.2.53
Source of numerous attacks
192.0.2.16/28
Danyliw & Stoecker Expires March 02, 2014 [Page 71] Internet-Draft IODEF August 2013
Source of heavy scanning over past 1-month
192.0.2.241
C2 IRC server
8. The IODEF Schema Incident Object Description Exchange Format v2.0, RFC5070-bis Danyliw & Stoecker Expires March 02, 2014 [Page 72] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 73] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 74] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 75] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 77] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 78] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 80] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 83] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 84] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 85] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 86] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 87] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 88] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 89] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 90] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 91] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 93] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 94] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 95] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 97] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 100] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 101] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 102] Internet-Draft IODEF August 2013 Danyliw & Stoecker Expires March 02, 2014 [Page 103] Internet-Draft IODEF August 2013 9. Security Considerations The IODEF data model itself does not directly introduce security issues. Rather, it simply defines a representation for incident information. As the data encoded by the IODEF might be considered privacy sensitive by the parties exchanging the information or by those described by it, care needs to be taken in ensuring the appropriate disclosure during both document exchange and subsequent processing. The former must be handled by a messaging format, but the latter risk must be addressed by the systems that process, store, and archive IODEF documents and information derived from them. The contents of an IODEF document may include a request for action or an IODEF parser may independently have logic to take certain actions based on information that it finds. For this reason, care must be taken by the parser to properly authenticate the recipient of the document and ascribe an appropriate confidence to the data prior to action. 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 [18] and its associated transport binding IODEF/RID over SOAP [19] provide such security. 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. The issue of enforcement is not a technical problem. Danyliw & Stoecker Expires March 02, 2014 [Page 104] Internet-Draft IODEF August 2013 10. IANA Considerations This document uses URNs to describe an XML namespace and schema conforming to a registry mechanism described in [15] Registration for the IODEF namespace: o URI: urn:ietf:params:xml:ns:iodef-2.0 o Registrant Contact: See the first author of 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 the "IODEF Schema" in Section 8 of this document. 11. Acknowledgments The following groups and individuals, listed alphabetically, contributed substantially to this document and should be recognized for their efforts. o Patrick Cain, Cooper-Cain Group, Inc. o The eCSIRT.net Project o The Incident Object Description and Exchange Format Working-Group of the TERENA task-force (TF-CSIRT) o Glenn Mansfield Keeni, Cyber Solutions, Inc. o Hiroyuki Kido, NARA Institute of Science and Technology o Kathleen Moriarty, EMC Corporation o Brian Trammell, ETH Zurich o Jan Meijer, SURFnet bv o Yuri Demchenko, University of Amsterdam Danyliw & Stoecker Expires March 02, 2014 [Page 105] Internet-Draft IODEF August 2013 12. References 12.1. Normative References [1] World Wide Web Consortium, "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C Recommendation , October 2000, . [2] World Wide Web Consortium, "XML XML Schema Part 1: Structures Second Edition", W3C Recommendation , October 2004, . [3] World Wide Web Consortium, "XML Schema Part 2: Datatypes Second Edition", W3C Recommendation , October 2004, . [4] World Wide Web Consortium, "Namespaces in XML", W3C Recommendation , January 1999, . [5] World Wide Web Consortium, "XML Path Language (XPath) 2.0", W3C Candidate Recommendation , June 2006, . [6] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [7] Philips, A. and M. Davis, "Tags for Identifying of Languages", RFC 4646, September 2006. [8] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 3986, January 2005`. [9] Freed, N. and J. Postel, "IANA Charset Registration Procedures", BCP 2978, October 2000. [10] Sciberras, A., "Schema for User Applications", RFC 4519, June 2006. [11] Resnick, P., "Internet Message Format", RFC 2822, April 2001. [12] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, July 2002. [13] International Organization for Standardization, "International Standard: Data elements and interchange Danyliw & Stoecker Expires March 02, 2014 [Page 106] Internet-Draft IODEF August 2013 formats - Information interchange - Representation of dates and times", ISO 8601, Second Edition, December 2000. [14] International Organization for Standardization, "International Standard: Codes for the representation of currencies and funds, ISO 4217:2001", ISO 4217:2001, August 2001. [15] Mealling, M., "The IETF XML Registry", RFC 3688, January 2004. 12.2. Informative References [16] Keeni, G., Demchenko, Y., and R. Danyliw, "Requirements for the Format for Incident Information Exchange (FINE)", Work in Progress, June 2006. [17] Debar, H., Curry, D., Debar, H., and B. Feinstein, "Intrusion Detection Message Exchange Format", RFC 4765, March 2007. [18] Moriarty, K., "Real-time Inter-network Defense", Work in Progress, April 2007. [19] Moriarty, K. and B. Trammell, "IODEF/RID over SOAP", Work in Progress, April 2007. [20] Shafranovich, Y., "Common Format and MIME Type for Comma- Separated Values (CSV) File ", RFC 4180, October 2005. Authors' Addresses Roman Danyliw CERT - Software Engineering Institute Pittsburgh, PA USA EMail: rdd@cert.org Paul Stoecker RSA Reston, VA USA EMail: paul.stoecker@rsa.com Danyliw & Stoecker Expires March 02, 2014 [Page 107]