The Cyber Observable Expression (CybOX) is a standardized language for encoding and communicating high-fidelity information about cyber observables, whether dynamic events or stateful measures that are observable in the operational cyber domain. By specifying a common structured schematic mechanism for these cyber observables, the intent is to enable the potential for detailed automatable sharing, mapping, detection and analysis heuristics. This document serves as an overview of those specifications and defines how they are used within the broader CybOX framework.

Status:

This document was last revised or approved by the OASIS Cyber Threat Intelligence (CTI) TC on the above date. The level of approval is also listed above. Check the “Latest version” location noted above for possible later revisions of this document. Any other numbered Versions and other technical work produced by the Technical Committee (TC) are listed at https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=cti#technical.

TC members should send comments on this specification to the TC’s email list. Others should send comments to the TC’s public comment list, after subscribing to it by following the instructions at the “Send A Comment” button on the TC’s web page at https://www.oasis-open.org/committees/cti/.

For information on whether any patents have been disclosed that may be essential to implementing this specification, and any offers of patent licensing terms, please refer to the Intellectual Property Rights section of the TC’s web page (https://www.oasis-open.org/committees/cti/ipr.php).

Citation format:

When referencing this specification the following citation format should be used:

[CybOX-v2.1.1-overview]

CybOX™ Version 2.1.1. Part 01: Overview. Edited by Trey Darley, Ivan Kirillov, Rich Piazza, and Desiree Beck. 20 June 2016. OASIS Committee Specification Draft 01 / Public Review Draft 01. http://docs.oasis-open.org/cti/cybox/v2.1.1/csprd01/part01-overview/cybox-v2.1.1-csprd01-part01-overview.html. Latest version: http://docs.oasis-open.org/cti/cybox/v2.1.1/part01-overview/cybox-v2.1.1-part01-overview.html.

Notices

All capitalized terms in the following text have the meanings assigned to them in the OASIS Intellectual Property Rights Policy (the "OASIS IPR Policy"). The full Policy may be found at the OASIS website.

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published, and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this section are included on all such copies and derivative works. However, this document itself may not be modified in any way, including by removing the copyright notice or references to OASIS, except as needed for the purpose of developing any document or deliverable produced by an OASIS Technical Committee (in which case the rules applicable to copyrights, as set forth in the OASIS IPR Policy, must be followed) or as required to translate it into languages other than English.

The limited permissions granted above are perpetual and will not be revoked by OASIS or its successors or assigns.

This document and the information contained herein is provided on an "AS IS" basis and OASIS DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

OASIS requests that any OASIS Party or any other party that believes it has patent claims that would necessarily be infringed by implementations of this OASIS Committee Specification or OASIS Standard, to notify OASIS TC Administrator and provide an indication of its willingness to grant patent licenses to such patent claims in a manner consistent with the IPR Mode of the OASIS Technical Committee that produced this specification.

OASIS invites any party to contact the OASIS TC Administrator if it is aware of a claim of ownership of any patent claims that would necessarily be infringed by implementations of this specification by a patent holder that is not willing to provide a license to such patent claims in a manner consistent with the IPR Mode of the OASIS Technical Committee that produced this specification. OASIS may include such claims on its website, but disclaims any obligation to do so.

OASIS takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on OASIS' procedures with respect to rights in any document or deliverable produced by an OASIS Technical Committee can be found on the OASIS website. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this OASIS Committee Specification or OASIS Standard, can be obtained from the OASIS TC Administrator. OASIS makes no representation that any information or list of intellectual property rights will at any time be complete, or that any claims in such list are, in fact, Essential Claims.

The name "OASIS" is a trademark of OASIS, the owner and developer of this specification, and should be used only to refer to the organization and its official outputs. OASIS welcomes reference to, and implementation and use of, specifications, while reserving the right to enforce its marks against misleading uses. Please see https://www.oasis-open.org/policies-guidelines/trademark for above guidance.

Portions copyright © United States Government 2012-2016. All Rights Reserved.

STIX™, TAXII™, AND CybOX™ (STANDARD OR STANDARDS) AND THEIR COMPONENT PARTS ARE PROVIDED “AS IS” WITHOUT ANY WARRANTY OF ANY KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY THAT THESE STANDARDS OR ANY OF THEIR COMPONENT PARTS WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT THE STANDARDS OR THEIR COMPONENT PARTS WILL BE ERROR FREE, OR ANY WARRANTY THAT THE DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE STANDARDS OR THEIR COMPONENT PARTS. IN NO EVENT SHALL THE UNITED STATES GOVERNMENT OR ITS CONTRACTORS OR SUBCONTRACTORS BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT, INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM, OR IN ANY WAY CONNECTED WITH THESE STANDARDS OR THEIR COMPONENT PARTS OR ANY PROVIDED DOCUMENTATION, WHETHER OR NOT BASED UPON WARRANTY, CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT OF THE RESULTS OF, OR USE OF, THE STANDARDS, THEIR COMPONENT PARTS, AND ANY PROVIDED DOCUMENTATION. THE UNITED STATES GOVERNMENT DISCLAIMS ALL WARRANTIES AND LIABILITIES REGARDING THE STANDARDS OR THEIR COMPONENT PARTS ATTRIBUTABLE TO ANY THIRD PARTY, IF PRESENT IN THE STANDARDS OR THEIR COMPONENT PARTS AND DISTRIBUTES IT OR THEM “AS IS.”

Table of Contents

1 Introduction. 6

1.1 CybOX Specification Documents. 6

1.2 Document Conventions. 6

1.2.1 Fonts. 6

1.2.2 UML Package References. 7

1.2.3 UML Diagrams. 7

1.3 Terminology. 8

1.4 Normative References. 8

1.5 Non-Normative References. 8

2 Language Modularity. 9

2.1 Core Data Model 9

2.2 Object Models. 9

2.3 Events and Actions Data Models. 11

2.4 Common Data Model 11

2.4.1 Object Property Model 11

2.5 Default Extensions Data Model 14

2.6 Default Vocabularies. 14

2.7 Basic Data Types. 14

2.7.1 Common Basic Data Types. 14

2.7.2 Specializations of the BasicString Data Type. 15

3 Data Model Conventions. 17

3.1 UML Packages. 17

3.2 Naming Conventions. 18

3.3 Identifiers. 18

4 Relationships to Other Externally-defined Data Models. 19

4.1 Customer Information Quality (CIQ) 19

4.2 Common Platform Enumeration (CPE) 19

5 Conformance. 20

Appendix A. Acknowledgments. 21

Appendix B. Revision History. 25

1 Introduction

[All text is normative unless otherwise labeled]

The Cyber Observable Expression (CybOX™) provides a common structure for representing cyber observables across and among the operational areas of enterprise cyber security. CybOX improves the consistency, efficiency, and interoperability of deployed tools and processes, and it increases overall situational awareness by enabling the potential for detailed automatable sharing, mapping, detection, and analysis heuristics.

This CybOX specification overview document serves as a unifying document for the full set of CybOX specification documents. In Section 0, we discuss additional specification documents, in Section 1.2, we provide document conventions, and in Section 1.3, we provide terminology. References are given in Sections 1.4 and 1.5. In Section 2 we discusses the modularity of CybOX, and summarizes the relationship of CybOX to other languages. In section 3, we discuss conventions common across all of the data models. Conformance information is also provided in Section 4.

1.1 CybOX Specification Documents

The CybOX specification consists of a formal UML model and a set of textual specification documents that explain the UML model. Specification documents have been written for each of the individual data models that compose the full CybOX UML model.

CybOX has a modular design comprising two fundamental data models and a collection of Object data models. The fundamental data models – CybOX Core and CybOX Common – provide essential CybOX structure and functionality. The CybOX Objects, defined in individual data models, are precise characterizations of particular types of observable cyber entities (e.g., HTTP session, Windows registry key, DNS query). Additionally, the full CybOX data model includes various extension data models and a set of default controlled vocabularies.

Use of the CybOX Core and Common data models is required; however, use of the CybOX Object data models is purely optional: users select and use only those Objects and corresponding data models that are needed. Importing the entire CybOX suite of data models is not necessary.

1.2 Document Conventions

The following conventions are used in this document.

1.2.1 Fonts

The following font and font style conventions are used in the document:

· Capitalization is used for CybOX high level concepts, which are defined in CybOX™ Version 2.1.1 Part 1: Overview.

Examples: Action, Object, Event, Property

· The Courier New font is used for writing UML objects.

Examples: ActionType, cyboxCommon:BaseObjectPropertyType

Note that all high level concepts have a corresponding UML object. For example, the Action high level concept is associated with a UML class named, ActionType.

· The ‘italic’ font (with single quotes) is used for noting actual, explicit values for CybOX Language properties. The italic font (without quotes) is used for noting example values.

Example: ‘HashNameVocab-1.0,’ high, medium, low

1.2.2 UML Package References

Each CybOX data model is captured in a different UML package (e.g., Core package) where the packages together compose the full CybOX UML model. To refer to a particular class of a specific package, we use the format package_prefix:class, where package_prefix corresponds to the appropriate UML package.

1.2.3 UML Diagrams

This specification makes use of UML diagrams to visually depict relationships between CybOX Language constructs. Note that the diagrams have been extracted directly from the full UML model for CybOX; they have not been constructed purely for inclusion in the specification documents. Typically, diagrams are included for the primary class of a data model, and for any other class where the visualization of its relationships between other classes would be useful. This implies that there will be very few diagrams for classes whose only properties are either a data type or a class from the CybOX Common data model. Other diagrams that are included correspond to classes that specialize a superclass and abstract or generalized classes that are extended by one or more subclasses.

In UML diagrams, classes are often presented with their attributes elided, to avoid clutter. A class presented with an empty section at the bottom of the icon indicates that there are no attributes other than those that are visualized using associations.

1.2.3.1 Class Properties

Generally, a class property can be shown in a UML diagram as either an attribute or an association (i.e., the distinction between attributes and associations is somewhat subjective). In order to make the size of UML diagrams in the specifications manageable, we have chosen to capture most properties as attributes and to capture only higher level properties as associations, especially in the main top-level component diagrams. In particular, we will always capture properties of UML data types as attributes.

1.2.3.2 Diagram Icons and Arrow Types

Diagram icons are used in a UML diagram to indicate whether a shape is a class, enumeration, or a data type, and decorative icons are used to indicate whether an element is an attribute of a class or an enumeration literal. In addition, two different arrow styles indicate either a directed association relationship (regular arrowhead) or a generalization relationship (triangle-shaped arrowhead). The icons and arrow styles we use are shown and described in Table 1‑1.

Table 1‑1. UML diagram icons

Icon	Description
	This diagram icon indicates a class. If the name is in italics, it is an abstract class.
	This diagram icon indicates an enumeration.
	This diagram icon indicates a data type.
	This decorator icon indicates an attribute of a class. The green circle means its visibility is public. If the circle is red or yellow, it means its visibility is private or protected.
	This decorator icon indicates an enumeration literal.
	This arrow type indicates a directed association relationship.
	This arrow type indicates a generalization relationship.

1.3 Terminology

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

1.4 Normative References

[RFC2119] Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, BCP 14, RFC 2119, March 1997. http://www.ietf.org/rfc/rfc2119.txt.

[CPE] Common Platform Enumeration (CPE). (2014, Nov. 28). The MITRE Corporation. [Online]. Available: http://cpe.mitre.org.

[CIQ] Customer Information Quality (CIQ) Specifications Version 3.0. Edited by Ram Kumar. 8 April 2008. OASIS Public Review Draft 03. Available: http://docs.oasis-open.org/ciq/v3.0/specs/ciq-specs-v3.html.

[W3DT] “XML Schema Part 2: Datatypes Second Edition,” W3C Recommendation, 28 October 2004. Available: http://www.w3.org/TR/xmlschema-2.

[CAPEC] Common Attack Pattern Enumeration and Classification (CAPEC). (2014, Nov. 7). The MITRE Corporation. [Online]. Available: http://capec.mitre.org.

[CEE] Common Event Expression (CEE). (2014, Nov. 28). The MITRE Corporation. [Online]. Available: http://cee.mitre.org.

[CVE] Common Vulnerabilities and Exposures (CVE). (2015, Jul. 28). The MITRE Corporation. [Online]. Available: http://cve.mitre.org.

[CWE] Common Weakness Enumeration (CWE). (2014, Jul. 31). The MITRE Corporation. [Online]. Available: http://cwe.mitre.org.

[ISO8601] Date and time format – ISO 8601 (n.d.). International Organization for Standardization (ISO). [Online]. Available: http://www.iso.org/iso/home/standards/iso8601.htm. Accessed Aug. 23, 2015.

[RFC3986] Berners-Lee, T., Fielding, R. and Masinter, L., “Uniform Resource Identifier (URI): Generic Syntax,” STD 66, RFC 3986, January 2005. Available: https://www.ietf.org/rfc/rfc3986.txt.

[RFC5646] Phillips, A. and Davis, M., “Tags for Identifying Languages,” BCP 47, RFC 5646, September 2009. Available: http://www.ietf.org/rfc/rfc5646.txt.

[W3Name] “Namespaces in XML 1.0 (Third Edition),” W3C Recommendation, 8 December 2009. Available: http://www.w3.org/TR/REC-xml-names.

1.5 Non-Normative References

[UML-2.4.1] Documents associated with Unified Modeling Language (UML), V2.4.1. (Aug. 2011). The Object Management Group (OMG). [Online]. Available: http://www.omg.org/spec/UML/2.4.1/.

2 Language Modularity

2.1 Core Data Model

The CybOX Core data model defines the four main classes: Action, Event, Observable and Object which corresponds to the primary structure characterized in CybOX. Please see CybOX™ Version 2.1.1 Part 3: Core for complete information on the CybOX Core data model.

2.2 Object Models

Each release of the CybOX language includes a particular set of Objects that are part of the release. There are eighty-eight different Object data models in CybOX 2.1.1. They cover a varied collection of artifacts that are pertinent to the cyber threat domain. The data model for each of these Objects is defined by its own UML package that describes the context-specific classes and properties that comprise the Object. As stated in the introduction, the use of any particular CybOX Object data models is purely optional: users select and use only those Objects and corresponding data models that are needed.

The grouping of Objects below is for expository purposes only. It does not suggest or imply the need to use of any particular Object data model.

Host-based Artifacts

File-related

Library
Windows Pipe
Pipe
Unix Pipe
Windows Filemapping
File

File
Image File
PDF File
Archive File
Windows File
Unix File
Windows Executable File

Memory-related

Windows Critical Section
Semaphore
Windows Semaphore
Windows Waitable Timer
Mutex
Windows Mutex
Windows Hook
Windows Kernel Hook
Windows Memory Page Region
Windows Handle
Memory
Windows Mailslot

Mobile

SMS Message

Process-related

Process
Windows Thread
Unix Process
Windows Process

Disk-related

Disk
Disk Partition
Volume
Unix Volume
Windows Volume

Network-related

Network Socket
Socket Address
Network Route Entry
Windows Network Route Entry
Unix Network Route Entry
Windows Network Share
Hostname
ARP Cache
URL History

Device/System

Device
System
Windows System

OS Metadata

Account
User Account
GUI

GUI
GUI Window
GUI Dialog Box

Unix/Linux

Unix User Account
Linux Package

Windows

Windows Prefetch
Windows Task
Windows Service
Windows System Restore
Windows Computer Account
Windows User Account
Windows Driver
Windows Service
Windows Event
Windows Event Log
Windows Registry Key
Windows Kernel

Network-based Artifacts

Email Message
DNS

DNS Record
DNS Query
DNS Cache

Network Route
Network Subnet
Network Connection
Network Flow
Network Packet
HTTP Session
AS
Address
Email Message
URI
Port
Domain Name
Whois

Misc.

Code
User Session
API
Custom
Link
Product
X509 Certificate
Artifact

The Object data models are split into three major categories: Host-based artifacts, Network-based artifacts, and the catch-all miscellaneous artifacts. Among the Host-based artifacts, there are many data models that are extensions of others in order to define properties specific to the Windows or Unix operating systems. Some of the Object data models are very simple (e.g. DNS_Cache), containing one or two UML classes or data types; others are quite complex, encompassing many UML classes (e.g., PDF_File). Each individual Object data model has a main toplevel class, which is usually named after the UML package name (e.g., the main class in the PDF File Object data model is PDFFileObjectType).

2.3 Events and Actions Data Models

The Event and Action data models are designed to support modular expression of any event made up of one or more actions with the ability to relate actions to one another and to relate actions to relevant objects. The Action data model allows expression of the nature of the action, any relevant arguments and relationships to any relevant objects including the nature of the relationship and any specific effects the action has on the object.

2.4 Common Data Model

The CybOX Common data model defines object classes that are shared across the various CybOX data models. At a high level, the CybOX Common data model provides object property classes, content aggregation classes, shared classes, and a pattern class for permitting complex (i.e. regular-expression based) specifications. Please see CybOX™ Version 2.1.1 Part 2: Common for complete information on the CybOX Common data model.

2.4.1 Object Property Model

The Object Property data model in CybOX is sophisticated, enabling the description of complex Observables. Observables can be made up of Objects or Events. In this section, we will concentrate on the Object aspect of an Observable.

Objects have two main properties, Properties and Related_Objects. This is shown in Figure 2‑1.

Figure 2‑1. UML diagram for ObjectType class

The Object data models, described in Section 2.2, are not extensions of ObjectType, but instead are used in an ObjectType class instance via the Properties property. Accordingly, they are extensions of ObjectPropertiesType, an abstract class. Notice that only a single toplevel instance from one of the Object data models is specified in the Properties property. Instances of other Objects can be referred to via the Related_Objects property.

Once the Object data model to be used in an ObjectType instance is selected, its properties can be assigned values. Such Object properties are based on one of four different kinds of property types:

· BasicTypes

· ObjectPropertyType extension classes

· Other classes defined in the same Object domain model

· Other toplevel classes from other Object domain models.

The following figures provide an example.

Figure 2‑2. Toplevel class of the Email_Message_Object data model

The EmailMessageObjectType class extends the ObjectPropertiesType, and therefore can be used in the ObjectType class (Figure 2‑2). The properties of EmailMessageObjectType use other classes from the same UML package as well as StringObjectPropertyType, an extension of ObjectPropertyType.

Figure 2‑3. Details of other classes of the Email_Message_Object data model

Expanding the detail of the EmailHeaderType class (Figure 2‑3), one can see that in addition to data type-based properties extended from the ObjectPropertyType class (e.g., IntegerObjectPropertyType) it also makes use of a class from the domain model of another Object (AddressObjectType). Notice that AddressObjectType contains properties that use data types from the BasicTypes package (see Section 2.7).

Figure 2‑4. UML diagram of the BaseObjectPropertyType data type

Use of UML data types that extend from BaseObjectPropertyType enables a producer of content to include much more detail about the value of an Object’s property (Figure 2‑4). BaseObjectPropertyType data type extends from BaseObjectPropertyGroup, which is an abstract data type that contains the auxiliary metadata properties associated with the main property value being represented. For example, when using StringObjectPropertyType to describe the File_Name property of a File Object, one might want to include that the observed encoding of the string is “windows-1251”.

In addition, the BaseObjectPropertyType data type also inherits from PatternFieldGroup data type. This data type incorporates pattern matching capabilities to all specializations of BaseObjectPropertyType. An example of using properties from PatternFieldGroup would be to use a StringObjectPropertyType to specify that the File Object’s File_Extension property satisfied the condition: not equal to “exe”.

Accordingly, it follows that properties from BaseObjectPropertyGroup are used only when specifying an actual observation and properties from PatternFieldGroup are used only when specifying an observable pattern.

2.5 Default Extensions Data Model

A primary design principle of CybOX is to avoid duplicating data models that already exist for capturing cyber threat information. Therefore, CybOX leverages a number of other structured languages and identifiers through the use of default extensions.

More precisely, the CybOX Default Extensions data model provides loose-coupling mechanisms and default extensions for leveraging constituent data models such as the Common Platform Enumeration [CPE] and OASIS Customer Information Quality model [CIQ].

Please see CybOX™ Version 2.1.1 Part 4: Default Extensions for complete information on the CybOX Default Extensions data model.

2.6 Default Vocabularies

For some properties captured in CybOX, a content creator may choose to constrain the set of possible values by referencing an externally-defined vocabulary or by leveraging a default vocabulary class defined within CybOX. Alternatively, the content creator may use an arbitrary value without specifying any vocabulary. Please see CybOX™ Version 2.1.1 Part 5: Vocabularies for more information about the default vocabularies defined in CybOX.

2.7 Basic Data Types

The Basic Data Types data model defines basic UML data types used in CybOX. As stated in the [UML 2.4.1] specification, UML data types are similar to UML classes, but also different:

“A data type is a special kind of classifier, similar to a class. It differs from a class in that instances of a data type are identified only by their value. All copies of an instance of a data type and any instances of that data type with the same value are considered to be equal instances. Instances of a data type that have attributes (i.e., is a structured data type) are considered to be equal if the structure is the same and the values of the corresponding attributes are equal. If a data type has attributes, then instances of that data type will contain attribute values matching the attributes.”

Although four of the requisite primitive data types (Boolean, Integer, String, UnlimitedNatural) are defined in UML, the need for a broader set in CybOX drove the decision to define a complete set of basic data types in a separate, stand-alone UML package (the Basic Data Types data model). We explicitly define the data types in the Basic Data Types data model in Sections 2.7.1 and 2.7.2.

Note, that the use of UML data types from the Basic Data Types data model (e.g., BasicString, Boolean) is not the same as using UML data types defined as specializations of BaseObjectPropertyType (e.g., StringObjectPropertyType, HexBinaryObjectPropertyType, etc.). The latter data types permits the use of properties from BaseObjectPropertyGroup and PatternFieldGroup, which allow for a much richer characterization of cyber observables. Also, it’s worth noting that not all data types defined in the Basic Data Types data model are used in CybOX.

2.7.1 Common Basic Data Types

Common data types, such as string and integer, are defined in the Basic DataTypes data model and adhere to the following definitions shown in Table 2‑1. These definitions are based on the specification of the corresponding data types found in [W3DT].

Table 2‑1. Common basic data types

Data Type	Definition
BasicString	The BasicString data type is a sequence of characters. Currently, characters are defined using the UTF-8 character encoding. The number of characters allowed is finite, but unbounded.
Boolean	The Boolean data type is defined with two possible literals: ‘true’ and ‘false’.
Decimal	The Decimal data type is a sequence of decimal digits, with perhaps an intervening decimal point, “.”. The number of digits on either side of the decimal point is finite, but unbounded. Often used to express currency amounts.
Integer	The Integer data type is a sequence of decimal digits, with perhaps a leading minus sign “-“. The number of decimal digits allowed is finite, but unbounded.
NonNegativeInteger	The NonNegativeInteger data type is a restriction on the Integer data type such that the leading minus sign is not allowed.
PositiveInteger	The PositiveInteger data type is a restriction on the NonNegativeInteger data type that disallows zero (0).

2.7.2 Specializations of the BasicString Data Type

The data types in Table 2‑2 correspond to strings that have semantics associated with them. Because of this, they usually are restricted to a certain pattern, defined via a regular expression, and/or more formally defined in a standardization document.

Table 2‑2. Specializations of the BasicString Data Type

Data Type	Definition
CAPEC_ID	The CAPEC_ID data type is a restriction on the BasicString data type, such that it adheres to the regular expression “CAPEC-\d+”. The CAPEC_ID values should correspond to those defined at [CAPEC].
CCE_ID	The CCE_ID data type is a restriction on the BasicString data type such that it adheres to the regular expression “CCE-\d+\d”. The CCE_ID values should correspond to those defined at [CEE].
CVE_ID	The CVE_ID data type is a restriction on the BasicString data type such that it adheres to the regular expression “CVE-\d\d\d\d+\d+”. The CVE_ID values should correspond to those defined at [CVE].
CWE_ID	The CWE_ID data type is a restriction on the BasicString data type such that it adheres to the regular expression “CWE-\d+”. The CWE_ID values should correspond to those defined at [CWE].
DateTime	The DateTime data type is a restriction on the BasicString data type such that it adheres to the standard defined in [ISO8601].
HexBinary	The HexBinary data type is a restriction on the BasicString data type such that it adheres to the regular expression [0-9A-Fa-f]*. The number of characters allowed is finite but unbounded. The number of digits must be even in length.
LanguageCode	The LanguageCode data type is a restriction on the BasicString data type, such that it adheres to the standard defined in [RFC5646].
QualifiedName	The QualifiedName data type is a restriction on the BasicString data type such that it adheres to the requirements specified in [W3Name].
NoEmbeddedQuoteString	The NoEmbeddedQuoteString data type is a restriction on the BasicString data type such that it does not include any double quote characters. This data type captures properties that were attributes in the XML model.
URI	The URI data type is a restriction on the BasicString data type such that it adheres to the standard defined at [RFC3986].

3 Data Model Conventions

The following general information and conventions are used to define the individual data models in CybOX™ Version 2.1.1 Part 6: UML Model. It should be noted that the CybOX data models actually evolved as XML schemas, and as a consequence, our UML model follows some conventions so as to be compatible with the preexisting XML implementation. However, we have abstracted away from the XML implementation as much as possible.

3.1 UML Packages

Each CybOX data model is captured in a different UML package (e.g., Core package, File_Object package, etc.). To refer to a particular class of a specific package, we use the format package_prefix:class, where package_prefix corresponds to the appropriate UML package. Table 3‑1 lists the basic packages used throughout the CybOX data model specification documents, along with the prefix notation and an example. Descriptions of the packages are provided in Section 2.

Table 3‑1. Package prefixes used by the CybOX Language

Package	CybOX Core
Prefix	cybox
Description	The CybOX Core data model defines the main classes of the CybOX data model, such as ActionType, EventType, ObservableType and ObjectType.
Example	cyboxCore:ObservableType

Package	CybOX Common
Prefix	cyboxCommon
Description	The CybOX Common data model defines classes that are shared across the various CybOX data models.
Example	cyboxCommon:ConfidenceType

Package	CybOX Default Vocabularies
Prefix	cyboxVocabs
Description	The CybOX default vocabularies define the classes for default controlled vocabularies used within CybOX.
Example	cyboxVocabs:ActionTypeVocab

Package	CybOX Basic Data Types
Prefix	basicDataTypes
Description	The Basic Data Types data model defines the types used within CybOX.
Example	basicDataTypes:URI

3.2 Naming Conventions

The UML classes, enumerations, and properties defined in CybOX follow the particular naming conventions outlined in Table 3‑2.

Table 3‑2. Naming formats of different object types

Object Type	Format	Example
Class	CamelCase ending with “Type”	IndicatorBaseType
Property (simple)	Lowercase with underscores between words	capec_id
Property (complex)	Capitalized with underscores between words	Associated_Actor
Enumeration	CamelCase ending with “Enum”	DateTimePrecisionEnum
Enumeration value	varies	Flash drive; Public Disclosure; Externally-Located
Data type	CamelCase or if the words are acronyms, all capitalized with underscores between words.	PositiveInteger; CVE_ID

3.3 Identifiers

Optional identifiers (IDs) can be assigned to several CybOX constructs so that the constructs can be unambiguously referenced. Technically, the decision to specify an ID on a given construct is optional based on the specifics of the usage context. As a general rule, specifying IDs on particular instances of constructs enables clear referencing, relating, and pivoting.

In CybOX v2.1.1, each CybOX ID is a fully qualified name, which consists of a producer namespace and a unique identifier. The producer namespace is a short-hand prefix, which is separated from the unique identifier by a colon (“:”):

[producer namespace]:[unique identifier]

This format provides high assurance that IDs will be both meaningful and unique. Meaning comes from producer namespace, which denotes who is producing it, and uniqueness comes from the unique identifier.

4 Relationships to Other Externally-defined Data Models

CybOX™ Version 2.1.1 leverages several other externally-defined data models that are relevant to the cyber threat domain. A listing of these other data models is given below.

Please see CybOX™ Version 2.2.1 Part 4: Default Extensions for further information on all of the externally-defined data models CybOX leverages by default (with the exception of CybOX, for which a different reference is given in Section Error! Reference source not found.).

4.1 Customer Information Quality (CIQ)

The OASIS Customer Information Quality (CIQ) Version 3.0 is a set of XML specifications for representing characteristic information about individuals and organizations [CIQ]. By extending the CybOX Common AddressAbstractType and IdentityType classes, CybOX™ Version 2.2.1 leverages CIQ Version 3.0 to capture geographic address information and identity information associated with Threat Actors, victims, and sources of information.

4.2 Common Platform Enumeration (CPE)

CPE is a structured naming scheme for information technology systems, software, and packages. Based upon the generic syntax for Uniform Resource Identifiers (URI), CPE includes a formal name format, a method for checking names against a system, and a description format for binding text and tests to a name. An XSD schema for CPE version 2.3 can be found at [CPE].

5 Conformance

Implementations have discretion over which parts (components, properties, extensions, controlled vocabularies, etc.) of CybOX they implement (e.g., Observable/Object).

[1] Conformant implementations must conform to all normative structural specifications of the UML model or additional normative statements within this document that apply to the portions of CybOX they implement (e.g., Implementers of the entire Observable class must conform to all normative structural specifications of the UML model regarding the Observable class or additional normative statements contained in the document that describes the Observable class).

[2] Conformant implementations are free to ignore normative structural specifications of the UML model or additional normative statements within this document that do not apply to the portions of CybOX they implement (e.g., Non-implementers of any particular properties of the Observable class are free to ignore all normative structural specifications of the UML model regarding those properties of the Observable class or additional normative statements contained in the document that describes the Observable class).

The conformance section of this document is intentionally broad and attempts to reiterate what already exists in this document.

Appendix A. Acknowledgments

The following individuals have participated in the creation of this specification and are gratefully acknowledged:

Aetna

David Crawford

AIT Austrian Institute of Technology

Roman Fiedler

Florian Skopik

Australia and New Zealand Banking Group (ANZ Bank)

Dean Thompson

Blue Coat Systems, Inc.

Owen Johnson

Bret Jordan

Century Link

Cory Kennedy

CIRCL

Alexandre Dulaunoy

Andras Iklody

Raphaël Vinot

Citrix Systems

Joey Peloquin

Dell

Will Urbanski

Jeff Williams

DTCC

Dan Brown

Gordon Hundley

Chris Koutras

EMC

Robert Griffin

Jeff Odom

Ravi Sharda

Financial Services Information Sharing and Analysis Center (FS-ISAC)

David Eilken

Chris Ricard

Fortinet Inc.

Gavin Chow

Kenichi Terashita

Fujitsu Limited

Neil Edwards

Frederick Hirsch

Ryusuke Masuoka

Daisuke Murabayashi

Google Inc.

Mark Risher

Hitachi, Ltd.

Kazuo Noguchi

Akihito Sawada

Masato Terada

iboss, Inc.

Paul Martini

Individual

Jerome Athias

Peter Brown

Elysa Jones

Sanjiv Kalkar

Bar Lockwood

Terry MacDonald

Alex Pinto

Intel Corporation

Tim Casey

Kent Landfield

JPMorgan Chase Bank, N.A.

Terrence Driscoll

David Laurance

LookingGlass

Allan Thomson

Lee Vorthman

Mitre Corporation

Greg Back

Jonathan Baker

Sean Barnum

Desiree Beck

Nicole Gong

Jasen Jacobsen

Ivan Kirillov

Richard Piazza

Jon Salwen

Charles Schmidt

Emmanuelle Vargas-Gonzalez

John Wunder

National Council of ISACs (NCI)

Scott Algeier

Denise Anderson

Josh Poster

NEC Corporation

Takahiro Kakumaru

North American Energy Standards Board

David Darnell

Object Management Group

Cory Casanave

Palo Alto Networks

Vishaal Hariprasad

Queralt, Inc.

John Tolbert

Resilient Systems, Inc.

Ted Julian

Securonix

Igor Baikalov

Siemens AG

Bernd Grobauer

Soltra

John Anderson

Aishwarya Asok Kumar

Peter Ayasse

Jeff Beekman

Michael Butt

Cynthia Camacho

Aharon Chernin

Mark Clancy

Brady Cotton

Trey Darley

Mark Davidson

Paul Dion

Daniel Dye

Robert Hutto

Raymond Keckler

Ali Khan

Chris Kiehl

Clayton Long

Michael Pepin

Natalie Suarez

David Waters

Benjamin Yates

Symantec Corp.

Curtis Kostrosky

The Boeing Company

Crystal Hayes

ThreatQuotient, Inc.

Ryan Trost

U.S. Bank

Mark Angel

Brad Butts

Brian Fay

Mona Magathan

Yevgen Sautin

US Department of Defense (DoD)

James Bohling

Eoghan Casey

Gary Katz

Jeffrey Mates

VeriSign

Robert Coderre

Kyle Maxwell

Eric Osterweil

Airbus Group SAS

Joerg Eschweiler

Marcos Orallo

Anomali

Ryan Clough

Wei Huang

Hugh Njemanze

Katie Pelusi

Aaron Shelmire

Jason Trost

Bank of America

Alexander Foley

Center for Internet Security (CIS)

Sarah Kelley

Check Point Software Technologies

Ron Davidson

Cisco Systems

Syam Appala

Ted Bedwell

David McGrew

Pavan Reddy

Omar Santos

Jyoti Verma

Cyber Threat Intelligence Network, Inc. (CTIN)

Doug DePeppe

Jane Ginn

Ben Othman

DHS Office of Cybersecurity and Communications (CS&C)

Richard Struse

Marlon Taylor

EclecticIQ

Marko Dragoljevic

Joep Gommers

Sergey Polzunov

Rutger Prins

Andrei Sîrghi

Raymon van der Velde

eSentire, Inc.

Jacob Gajek

FireEye, Inc.

Phillip Boles

Pavan Gorakav

Anuj Kumar

Shyamal Pandya

Paul Patrick

Scott Shreve

Fox-IT

Sarah Brown

Georgetown University

Eric Burger

Hewlett Packard Enterprise (HPE)

Tomas Sander

IBM

Peter Allor

Eldan Ben-Haim

Sandra Hernandez

Jason Keirstead

John Morris

Laura Rusu

Ron Williams

IID

Chris Richardson

Integrated Networking Technologies, Inc.

Patrick Maroney

Johns Hopkins University Applied Physics Laboratory

Karin Marr

Julie Modlin

Mark Moss

Pamela Smith

Kaiser Permanente

Russell Culpepper

Beth Pumo

Lumeta Corporation

Brandon Hoffman

MTG Management Consultants, LLC.

James Cabral

National Security Agency

Mike Boyle

Jessica Fitzgerald-McKay

New Context Services, Inc.

John-Mark Gurney

Christian Hunt

James Moler

Daniel Riedel

Andrew Storms

OASIS

James Bryce Clark

Robin Cover

Chet Ensign

Open Identity Exchange

Don Thibeau

PhishMe Inc.

Josh Larkins

Raytheon Company-SAS

Daniel Wyschogrod

Retail Cyber Intelligence Sharing Center (R-CISC)

Brian Engle

Semper Fortis Solutions

Joseph Brand

Splunk Inc.

Cedric LeRoux

Brian Luger

Kathy Wang

TELUS

Greg Reaume

Alan Steer

Threat Intelligence Pty Ltd

Tyron Miller

Andrew van der Stock

ThreatConnect, Inc.

Wade Baker

Cole Iliff

Andrew Pendergast

Ben Schmoker

Jason Spies

TruSTAR Technology

Chris Roblee

United Kingdom Cabinet Office

Iain Brown

Adam Cooper

Mike McLellan

Chris O’Brien

James Penman

Howard Staple

Chris Taylor

Laurie Thomson

Alastair Treharne

Julian White

Bethany Yates

US Department of Homeland Security

Evette Maynard-Noel

Justin Stekervetz

ViaSat, Inc.

Lee Chieffalo

Wilson Figueroa

Andrew May

Yaana Technologies, LLC

Anthony Rutkowski

The authors would also like to thank the larger CybOX Community for its input and help in reviewing this document.

Appendix B. Revision History

Revision	Date	Editor	Changes Made
wd01	15 December 2015	Desiree Beck Trey Darley Ivan Kirillov Rich Piazza	Initial transfer to OASIS template