Open Command and Control (OpenC2) Language Specification Version 2.0

Committee Specification Draft 02

15 May 2024

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Technical Committee:

OASIS Open Command and Control (OpenC2) TC

Chairs:

Duncan Sparrell (duncan@sfractal.com), sFractal Consulting LLC
Michael Rosa (mjrosa@nsa.gov), National Security Agency

Editors:

Duncan Sparrell (duncan@sfractal.com), sFractal Consulting LLC
Toby Considine (toby.considine@unc.edu), University of North Carolina at Chapel Hill
David Lemire (david.lemire@hii-tsd.com), National Security Agency

Abstract:

Cyber attacks are increasingly sophisticated, less expensive to execute, dynamic and automated. The provision of cyber defense via statically configured products operating in isolation is untenable. Standardized interfaces, protocols and data models will facilitate the integration of the functional blocks within a system and between systems. Open Command and Control (OpenC2) is a concise and extensible language to enable machine-to-machine communications for purposes of command and control of cyber defense components, subsystems and/or systems in a manner that is agnostic of the underlying products, technologies, transport mechanisms or other aspects of the implementation. It should be understood that a language such as OpenC2 is necessary but insufficient to enable coordinated cyber responses that occur within cyber relevant time. Other aspects of coordinated cyber response such as sensing, analytics, and selecting appropriate courses of action are beyond the scope of OpenC2.

Status:

This document was last revised or approved by the OASIS Open Command and Control (OpenC2) TC on the above date. The level of approval is also listed above. Check the "Latest stage" 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://groups.oasis-open.org/communities/tc-community-home2?CommunityKey=a34c9baf-48b2-44c5-a567-018dc7d32296

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, technical-committee-comments@oasis-open.org

This specification is provided under the Non-Assertion Mode of the OASIS IPR Policy, the mode chosen when the Technical Committee was established. 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/openc2/ipr.php).

Note that any machine-readable content (Computer Language Definitions) declared Normative for this Work Product is provided in separate plain text files. In the event of a discrepancy between any such plain text file and display content in the Work Product's prose narrative document(s), the content in the separate plain text file prevails.

Key words:

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] and [RFC8174] when, and only when, they appear in all capitals, as shown here.

Citation format:

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

[OpenC2-Lang-v2.0]

Open Command and Control (OpenC2) Language Specification Version 2.0. Edited by Duncan Sparrell, Toby Considine, and David Lemire. 15 May 2024. OASIS Committee Specification Draft 02. https://docs.oasis-open.org/openc2/oc2ls/v2.0/csd02/oc2ls-v2.0-csd02.html. Latest stage: https://docs.oasis-open.org/openc2/oc2ls/v2.0/oc2ls-v2.0.html.

Notices

Copyright © OASIS Open 2024. All Rights Reserved.

Distributed under the terms of the OASIS IPR Policy.

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.

For complete copyright information please see the full Notices section in an Appendix below.

Table of Contents

• 1 Introduction
  • 1.1 Changes From Earlier Versions
  • 1.2 Glossary
    • 1.2.1 Definitions of Terms
    • 1.2.2 Acronyms and abbreviations
    • 1.2.3 Document Conventions
      • 1.2.3.1 Naming Conventions
      • 1.2.3.2 Font Colors and Style
  • 1.4 Purpose and Scope
• 2 OpenC2 Language Description
  • 2.1 OpenC2 Command
  • 2.2 OpenC2 Response
• 3 OpenC2 Language Definition
  • 3.1 Base Components and Structures
    • 3.1.1 Data Types
    • 3.1.2 Semantic Value Constraints
    • 3.1.3 Multiplicity
    • 3.1.4 Extensions
    • 3.1.5 Serialization
  • 3.2 Message
  • 3.3 Content
    • 3.3.1 OpenC2 Command
      • 3.3.1.1 Action
      • 3.3.1.2 Target
      • 3.3.1.3 Profile
      • 3.3.1.4 Command Arguments
    • 3.3.2 OpenC2 Response
      • 3.3.2.1 Response Status Code
      • 3.3.2.2 Response Results
    • 3.3.3 OpenC2 Event
    • 3.3.4 Message Signatures
  • 3.4 Type Definitions
    • 3.4.1 Target Types
      • 3.4.1.1 Artifact
      • 3.4.1.2 Device
      • 3.4.1.3 Domain Name
      • 3.4.1.4 Email Address
      • 3.4.1.5 Features
      • 3.4.1.6 File
      • 3.4.1.7 Internationalized Domain Name
      • 3.4.1.8 Internationalized Email Address
      • 3.4.1.9 IPv4 Address Range
      • 3.4.1.10 IPv4 Connection
      • 3.4.1.11 IPv6 Address Range
      • 3.4.1.12 IPv6 Connection
      • 3.4.1.13 IRI
      • 3.4.1.14 MAC Address
      • 3.4.1.15 Process
      • 3.4.1.16 URI
    • 3.4.2 Data Types
      • 3.4.2.1 Action-Targets
      • 3.4.2.2 Command-ID
      • 3.4.2.3 Date-Time
      • 3.4.2.4 Duration
      • 3.4.2.5 Feature
      • 3.4.2.6 Hashes
      • 3.4.2.7 Hostname
      • 3.4.2.8 Internationalized Hostname
      • 3.4.2.9 IPv4 Address
      • 3.4.2.10 IPv6 Address
      • 3.4.2.11 L4 Protocol
      • 3.4.2.12 Message-Type
      • 3.4.2.13 Namespace Identifier
      • 3.4.2.14 Payload
      • 3.4.2.15 Port
      • 3.4.2.16 Response-Type
      • 3.4.2.17 Targets
      • 3.4.2.18 Version
• 4 Mandatory Commands/Responses
  • 4.1 Implementation of 'query features' Command
  • 4.2 Examples of 'query features' Commands and Responses
    • 4.2.1 Example 1: Bare "query : features"
    • 4.2.2 Example 2: Query for Specific Features
    • 4.2.3 Example 3: Query Features Detailed Response with Multiple Profiles
• 5 Conformance
  • 5.1 Conformance Clause 1: Command
  • 5.2 Conformance Clause 2: Response
  • 5.3 Conformance Clause 3: Producer
  • 5.4 Conformance Clause 4: Consumer
• Appendix A. References
  • A.1 Normative References
  • A.2 Informative References
• Appendix B. Safety, Security and Privacy Considerations
• Appendix C. Acknowledgments
  • C.1 Special Thanks
  • C.2 Participants
• Appendix D. Revision History
• Appendix E. Examples
  • E.1 Example 1: Device Quarantine
  • E.2 Example 2: Block Connection
• Appendix F. Notices

1 Introduction

The content in this section is non-normative, except where it is marked normative.

OpenC2 is a suite of specifications that enables command and control of cyber defense systems and components. OpenC2 typically uses a request-response paradigm where a Command is encoded by a Producer (managing application) and transferred to a Consumer (managed device or virtualized function) using a secure transfer protocol, and the Consumer can respond with status and any requested information. An overview of the concepts that underlie OpenC2 and the structure of the suite of specifications can be found in the OpenC2 Architecture Specification [OpenC2-Arch-v1.0].

The goal of OpenC2 is to provide a language for interoperating between functional elements of cyber defense systems. This language, used in conjunction with OpenC2 Actuator Profiles (e.g., the [Stateless Packet Filtering AP]) and OpenC2 Transfer Specifications (e.g., for [MQTT] and [HTTPS]), allows for vendor-agnostic cybertime response to attacks.

This OpenC2 Language Specification provides the semantics for the essential elements of the language, the structure for Commands and Responses, and the schema that defines the proper syntax for the language elements that represents the Command or Response. It also describes the mechanisms for extending the capabilities of the language.

OpenC2 allows the application producing the commands to discover the set of capabilities supported by the managed devices. These capabilities permit the managing application to adjust its behavior to take advantage of the features exposed by the managed device. The capability definitions can be easily extended in a non-centralized manner, allowing standard and non-standard capabilities to be defined with semantic and syntactic rigor.

1.1 Changes From Earlier Versions

To Be Supplied.

1.2 Glossary

1.2.1 Definitions of Terms

This section is normative.

• Action: The task or activity to be performed (e.g., 'deny').

• Actuator: The Consumer that executes a Command.

• Actuator Profile (AP): A defined subset of the OpenC2 language (i.e., actions, targets, command arguments, results) plus any extensions required to specify the use of OpenC2 to command a particular function. Actuator Profiles are defined in JADN schemas associated with published actuator profile specification documents.

• Argument: A property of a Command that provides additional information on how to perform the Command, such as date/time, periodicity, duration, etc.

• Command: A Message defined by an Action-Target pair that is sent from a Producer and received by a Consumer.

• Consumer: A managed device / application that receives Commands. Note that a single device / application can have both Consumer and Producer capabilities. A Consumer will implement one or more Actuator Profiles.

• Message: A content- and transport-independent set of elements conveyed between Consumers and Producers.

• Producer: A manager application that sends Commands.

• Response: A Message from a Consumer to a Producer acknowledging a Command or returning the requested resources or status to a previously received Command.

• Specifier: A property or field that identifies a Target to some level of precision.

• Target: The object of the Action, i.e., the Action is performed on the Target (e.g., IP Address).

1.2.2 Acronyms and abbreviations

1.2.3 Document Conventions

1.2.3.1 Naming Conventions

The OpenC2 language is formally defined by a schema written in JSON Abstract Data Notation (JADN) [JADN-v1.0]. The naming conventions used in this specification are consistent with JADN's default conventions.

• All property names and literals are in lowercase, except when referencing canonical names defined in another standard (e.g., literal values from an IANA registry).

• All type names begin with an uppercase character.

• Property names and type names are between 1 and 32 characters long.

• Words in property names are separated with an underscore (_), while words in type names are separated with a hyphen (-).

• "Underscore" refers to Unicode "low line", U+005F; "hyphen" refers to Unicode "hyphen-minus", U+002D.

1.2.3.2 Font Colors and Style

The following color, font and font style conventions are used in this document:

• A fixed width font is used for all type names, property names, and literals.

• Property names are in bold style – 'created_at'.

• All examples in this document are expressed in JSON. They are in fixed width font, with straight quotes, black text and a light shaded background, and 4-space indentation. JSON examples in this document are representations of JSON Objects. They should not be interpreted as string literals. The ordering of object keys is insignificant. Whitespace before or after JSON structural characters in the examples are insignificant [RFC8259].

• Parts of the example may be omitted for conciseness and clarity. These omitted parts are denoted with ellipses (...).

Example:

{
    "action": "deny",
    "target": {
        "file": {
            "hashes": {
                "sha256": "22fe72a34f006ea67d26bb7004e2b6941b5c3953d43ae7ec24d41b1a928a6973"
            }
        }
    }
}

1.4 Purpose and Scope

This OpenC2 Language Specification defines the set of components to assemble a complete command and control Message and provides a framework so that the language can be extended. To achieve this purpose, the scope of this specification includes:

1. the set of Actions and options that may be used in Commands;
2. the set of Targets and Target Specifiers;
3. a syntax that defines the structure of Commands and Responses;
4. a JSON serialization of Commands and Responses;
5. the procedures for extending the language.

The OpenC2 language assumes that the event has been detected, a decision to act has been made, the act is warranted, and the initiator and recipient of the Commands are authenticated and authorized. The OpenC2 language was designed to be agnostic of the other aspects of cyber defense implementations that realize these assumptions. The following items are beyond the scope of this specification:

1. Language elements applicable to some Actuator functions, which may be defined in individual Actuator profiles.

2. Alternate serializations of Commands and Responses.

3. The enumeration of the protocols required for transport, information assurance, sensing, analytics and other external dependencies.

2 OpenC2 Language Description

The content in this section is non-normative.

The OpenC2 language has two distinct content types: Command and Response. The Command is sent from a Producer to a Consumer and describes an Action to be performed by the Consumer on a Target. The Response is sent from a Consumer, usually back to the Producer, and is a means to provide information (such as acknowledgment, status, etc.) as a result of a Command.

2.1 OpenC2 Command

A command has four main components, two required and two optional. The required components are the Action and the Target. The optional components are command Arguments and the Profile identifier. A command can also contain an optional Command identifier, if necessary. Section 3.3.1 defines the syntax of an OpenC2 Command.

The following list summarizes the main four components of a command.

• Action (required): The task or activity to be performed.

• Target (required): The object of the action. The Action is performed on the Target. Properties of the Target, called Target Specifiers, further identify the Target to some level of precision, such as a specific Target, a list of Targets, or a class of Targets.

• Arguments (optional): Provide additional information on how the command is to be performed, such as date/time, periodicity, duration, etc.

• Profile (optional): Specifies the Actuator Profile that defines the function to be performed by the command.

The Action and Target components are required and are populated by one of the Actions in Section 3.3.1.1 and and either a Target from Section 3.3.1.2 or an extension Target defined in an AP. A particular Target may be further refined by the Target type definitions in Section 3.4.1. Procedures to extend the Targets are described in Section 3.1.4.

Command Arguments, if present, influence the command by providing information such as timing, periodicity, duration, or other details on what is to be executed. They can also be used to convey the need for acknowledgment or additional status information about the execution of a command. The valid Arguments defined in this specification are in Section 3.3.1.4. Procedures to extend Arguments are described in Section 3.1.4.

The Profile field, if present, specifies the profile that defines the function to be performed. A Consumer executes the command if it supports the specified profile, otherwise the command is ignored. The Profile field may be omitted and typically will not be included in implementations where the functions of the recipients are unambiguous or when a high-level effects-based command is desired and tactical decisions on how the effect is achieved is left to the recipient. If Profile is omitted and the recipient supports multiple profiles, the command will be executed in the context of each profile that supports the command's combination of action and target.

2.2 OpenC2 Response

The Response is a Message sent from the recipient of a Command. Response messages provide acknowledgment, status, results from a query, or other information. At a minimum, a Response will contain a status code to indicate the result of performing the Command. Additional status text and response fields optionally provide more detailed information that is specific to or requested by the Command. Section 3.3.2 defines the syntax of an OpenC2 Response.

3 OpenC2 Language Definition

The content in this section is normative.

3.1 Base Components and Structures

OpenC2 data types are defined using using the types and options available in [JADN]. JADN is a UML-based information modeling language that defines data structure independently of data format. RFC 3444, "Information Models and Data Models", describes the main purpose of an information model as modeling objects at a conceptual level, independent of specific implementations or protocols used to transport the data. This concept of an information model is consistent with the goal of defining OpenC2 commands and responses independent of their representation in any specific implementation. JADN provides a tool for developing information models, which can be used to define and generate physical data models, validate information instances, and enable lossless translation across data formats. Information modeling concepts are discussed in more detail in Information Modeling with JADN [IM-JADN-v1.0].

This section provides a concise summary of JADN type definitions to facilitate readability; for more complete explanations refer to the JADN Committee Specification and the Information Modeling with JADN Committee Note.

3.1.1 Data Types

The use of JADN enables type definitions that are independent of both their representation within applications ("API" values) and their format for transmission between applications ("serialized" values). The data types used in OpenC2 Messages are:

• API values do not affect interoperability, and although they must exhibit the characteristics specified above, their representation within applications is unspecified. A Python application might represent the Map type as a dict variable, a javascript application might represent it as an object literal or an ES6 Map type, and a C# application might represent it as a Dictionary or a Hashtable.

• Serialized values are critical to interoperability, and this document defines a set of serialization rules that unambiguously define how each of the above types are serialized using a human-friendly JSON format. Other serialization rules, such as for XML, machine-optimized JSON, and Concise Binary Object Representation (CBOR) formats, exist but are out of scope for this document.

Usage Requirement:

• OpenC2 messages in JSON format SHALL be serialized in accordance with the rules defined in the JADN Specification [JADN], section 4.

OpenC2 type definitions are presented in this specification in table format. All table columns except Description are Normative, however any conflict between the table presentation and the JADN schema must be resolved by applying the schema definition. The Description column is always Non-normative.

Usage Requirement:

• The format-agnostic type definitions in Section 3.4 are Normative.

For types without individual field definitions (Primitive types and ArrayOf), the type definition includes the name of the type being defined and the definition of that type. This table defines a type called Email-Addr that is a String that has a semantic value constraint of email:

For Structured types, the definition includes the name of the type being defined, the built-in type on which it is based, and options applicable to the type as a whole. This is followed by a table defining each of the fields in the structure. This table defines a type called Args that is a Map containing at least one field. Each of the fields has an integer Tag/ID, a Name, and a Type. Each field in this example type definition is optional (Multiplicity = 0..1), but per the type definition (Multiplicity = 1..*) at least one field must be present.

Type: Args (Map{1..*})

The field columns present in a structure definition depends on the base type:

The ID column of Array and Record types contains the ordinal position of the field, numbered sequentially starting at 1. The ID column of Choice, Enumerated, and Map types contains tags with arbitrary integer values. IDs and Names are unique within each type definition.

3.1.2 Semantic Value Constraints

Structural validation alone may be insufficient to validate that an instance meets all the requirements of an application. Semantic validation keywords specify value constraints for which an authoritative definition exists.

Usage Requirements:

• Properties identified as conforming to eui SHOULD be interpreted according to the values documented in the [IEEE Registration Authority registry].

3.1.3 Multiplicity

Property tables for types based on Array, Choice, Map and Record include a multiplicity column (#) that specifies the minimum and maximum cardinality (number of elements) of a field. As used in the Unified Modeling Language ([UML]), typical examples of multiplicity are:

When a repeatable field type is converted to a separate ArrayOf() Type, multiplicity is converted to the array size, enclosed in curly brackets, e.g.,:

A multiplicity of 0..1 denotes a single optional value of the specified type. A multiplicity of 0..n denotes a field that is either omitted or is an array containing one or more values of the specified type.

An array containing zero or more values of a specified type cannot be created implicitly using multiplicity, it must be defined explicitly as a named ArrayOf type. The named type can then be used as the type of a required field (multiplicity 1). Results are unspecified if an optional field (multiplicity 0..1) is a named ArrayOf type with a minimum length of zero.

3.1.4 Extensions

One of the main design goals of OpenC2 is extensibility. Actuator Profiles define the language extensions that are meaningful and possibly unique to the Actuator.

Each Profile has a unique name used to identify the profile document and a short reference called a namespace identifier (NSID). The NSID is a prefix used to separate types defined in one profile document from types defined in other profiles or this specification. OpenC2 conventions for managing namespaces are described in Appendix F of the OpenC2 Architecture Specification [Openc2-Arch-v1.0].

Example: the OASIS standard Stateless Packet Filtering profile has:

• Namespace: http://docs.oasis-open.org/openc2/ns/ap/slpf/v1.0
• NSID: slpf
• Language-defined type: IPv4-Net
• Profile-defined type: slpf/Rule-ID

Example: the fictional, non-standard Superwidget Profile has:

• Namespace: http://www.acme.com/openc2/superwidget-v1.0.html
• NSID: acmesw
• Language-defined type: Device
• Profile-defined type: acmesw/Device

Usage Requirements:

• The list of Actions in Section 3.3.1.1 SHALL NOT be extended.

• Targets, defined in Section 3.3.1.2, MAY be extended. Extended Target type names MUST be prefixed with a namespace identifier followed by a slash ("/"). Extended target properties appear beneath (nested within) a profile property name.

Example: The Stateless Packet Filtering Profile supports both common and profile-specific targets:

Targets used in Consumers that support the SLPF actuator profile:

Type: Target (Choice)

Targets defined in the SLPF actuator profile:

Type: slpf/AP-Target (Choice)

In this example Command, the extended Target rule_number of type slpf/Rule-ID appears within the SLPF profile property name slpf:

{
    "action": "delete",
    "target": {
        "slpf": {
            "rule_number": 1234
        }
    }
}

Usage Requirement:

• Command Arguments, defined in Section 3.3.1.4, MAY also be extended using profile-defined types appearing within the profile property name.

Type: Args (Map)

Args defined in the SLPF actuator profile:

Type: slpf/AP-Args (Map)

Example: In this example Command, the extended Argument, direction of type slpf:Direction contained in type slpf:AP-Args, appears in the Stateless Packet Filtering property name slpf:

{
    "action": "deny",
    "target": {
        "ipv6_net": {...}
    },
    "args": {
        "slpf": {
            "direction": "ingress"
        }
    }
}

The Profile property of a Command, defined in Section&nbps;3.3.1.3, specifies the property name of the Actuator Profile that defines the function to be performed.

Example: In this example Command, the profile name slpf indicates that the deny ipv4_connection command is to be performed as defined by the Stateless Packet Filtering Profile.

{
    "action": "deny",
    "target": {
        "ipv4_connection": {...}
    },
    "profile": "slpf"
}

Usage Requirement:

• Response results, defined in Section 3.3.2.2, MAY be extended using the namespace identifier as the results name, called an extended results namespace. Extended results MUST be defined within the extended results namespace.

Example: In this example Response, the Response results property, rule_number, is defined within the Stateless Packet Filtering Profile namespace, slpf.

{
    "status": 200,
    "results": {
        "slpf": {
            "rule_number": 1234
        }
    }
}

3.1.5 Serialization

OpenC2 is agnostic of any particular serialization; however, implementations MUST support JSON serialization in accordance with

• [RFC7493] and
• [JADN].

Types defined with the ".ID" appended to the base type (Enumerated, Choice, Map) are serialized in accordance with [JADN].

3.2 Message

This language specification and one or more Actuator Profiles define the content of Commands and Responses, while transfer specifications define the on-the-wire format of a Message over specific secure transport protocols. Transfer specifications are agnostic with regard to content, and content is agnostic with regard to transfer protocol. This decoupling is accomplished by defining a standard message interface used to transfer any type of content over any transfer protocol.

A message is a content- and transport-independent set of elements conveyed between Producers and Consumers. To ensure interoperability all transfer specifications must unambiguously define how the Message elements in Table 3-1 are represented within the secure transport protocol. This does not imply that all Message elements must be used in all Messages. Content, content_type, and msg_type are required in all Messages. Other Message elements are not required by this specification but may be required by other specifications. The internal representation of a Message does not affect interoperability and is therefore beyond the scope of OpenC2.

Table 3-1. Common Message Elements

Usage Requirement:

• As an alternative to using protocol-specific mechanisms to convey message elements, transfer specifications MAY collect all message elements into a single Message structure used as a protocol payload.

The media type "application/openc2" is reserved with IANA to designate content in OpenC2 Message format. The Message structure and its media type are intended to remain stable across future versions of this specification.

Type: Message (Record)

Headers contains optional common message elements. Additional constraints on common header values may be defined. Additional headers may be defined. The "signature" field is used to contain an option digital signature to provide source authentication and integrity protections of the OpenC2 message.

Type: Headers (Map{1..*})

Body indicates the Message content format and is intended to support new types of OpenC2 Content such as command lists or bundle objects, but OpenC2 may also assign Body types for non-OpenC2 content such as STIX or CACAO objects.

Type: Body (Choice)

Type: OpenC2-Content (Choice)

Example JSON-serialized Message payload (without signature):

{
  "headers": {
    "request_id": "95ad511c-3339-4111-9c47-9156c47d37d3",
    "created": 1595268027000,
    "from": "Producer1@example.com",
    "to": ["consumer1@example.com", "consumer2@example.com", "consumer3@example.com"]
  },
  "body": {
    "openc2": {
      "request": {
        "action": "deny",
        "target": {
          "uri": "http://www.example.com" }}}}}

Usage Requirements:

• A Producer MUST include a request_id in the Message header of a Command if it requests a Response.

• The request_id of a Message SHOULD be a Version 4 UUID as specified in [RFC4122], Section 4.4.

• A Consumer MUST copy the request_id from the Message header of a Command into each Response to that Command.

3.3 Content

The purpose of this specification is to define the Action and Target portions of a Command and the common portions of a Response. The properties of the Command are defined in Section 3.3.1 and the properties of the Response are defined in Section 3.3.2.

In addition to the Action and Target, a Command has an optional Profile field. The semantics associated with Command and Response content are defined in the specified Actuator Profile.

3.3.1 OpenC2 Command

The Command defines an Action to be performed on a Target.

Type: OpenC2-Command (Record)

Usage Requirements:

• A Consumer receiving a Command with command_id absent and request_id present in the header of the Message MUST use the value of request_id as the command_id.

• If present, the args property MUST contain at least one element defined in Section 3.3.1.4.

• If a Consumer that implements multiple actuator profiles receives a Command with no Profile specified, the command will be executed in the context of each profile that supports the command's combination of action and target.

3.3.1.1 Action

Type: Action (Enumerated)

Usage Requirements:

• Each Command MUST contain exactly one Action defined in Section 3.3.1.1.

3.3.1.2 Target

Type: Target (Choice)

Usage Requirements:

• The target field in a Command MUST contain exactly one type of Target (e.g., ipv4_net).

3.3.1.3 Profile

OpenC2 maintains an administrative document listing current, planned, and extension actuator profile information.

Type: Profile (Enumerated)

3.3.1.4 Command Arguments

Type: Args (Map{1..*})

Usage Requirements:

• start_time, stop_time, duration:

  • If none are specified, then start_time is now, stop_time is never, and duration is infinity.

    • Only two of the three are allowed on any given Command and the third is derived from the equation stop_time = start_time + duration.

    • If only start_time is specified then stop_time is never and duration is infinity.

    • If only stop_time is specified then start_time is now and duration is derived.

    • If only duration is specified then start_time is now and stop_time is derived.

• response_requested:

  • If response_requested is specified as none and the Consumer successfully executes the Command then the Consumer SHOULD NOT send a Response.

  • If response_requested is specified as none and the Consumer encounters an error then the Consumer SHOULD send a Response with a status consistent with the error detected.

  • If response_requested is specified as ack then the Consumer SHOULD send a Response acknowledging receipt of the Command: {"status": 102}.

  • If response_requested is specified as status then the Consumer SHOULD send a Response containing the current status of Command execution.

  • If response_requested is specified as complete then the Consumer SHOULD send a Response containing the status or results upon completion of Command execution.

  • If response_requested is not explicitly specified then the Consumer SHOULD respond as if complete was specified.

3.3.2 OpenC2 Response

OpenC2-Response defines the structure of a response to OpenC2-Command.

Type: OpenC2-Response (Record)

Example:

{
    "status": 200,
    "results": {
        "versions": ["1.1"]
    }
}

Usage Requirements:

• All Responses MUST contain a status.

3.3.2.1 Response Status Code

Type: Status-Code (Enumerated.ID)

3.3.2.2 Response Results

Type: Results (Map{1..*})

Usage Requirements:

NOTE: Confirm whether any language schema changes are necessary to support this.

• pairs results SHOULD be grouped by profile such that a Producer processing the Response message can identify the commands available for each supported profile. See Example 3 in Section 4.2.

3.3.3 OpenC2 Event

OpenC2-Event defines the content of a one-way notification. This structure defines no common event fields, but is the point at which profile-defined event content may be added.

Type: OpenC2-Event (Map{1..*})

3.3.4 Message Signatures

To-Do: develop a replacement JSS-based example and add to Appendix E. Need to find tooling to assist.

Command and control mechanisms need to provide appropriate security controls protecting message content (especially authentication of command origin and protection of command integrity) so that Consumers receiving commands can proceed to execute them with confidence and Producers can have confidence that the feedback in response messages is meaningful. Digital signatures can provide both of those security properties. OpenC2 messages can be protected with digital signatures using standard mechanisms. ITU-T Recommendation X.590 [ITU-T X.590], JSON Signature Scheme (JSS) provides a signature mechanism for JSON content that aligns with the needs of OpenC2.

Usage Requirements:

• OpenC2 messages SHOULD be digitally signed, unless message integrity and source authentication are provided by other mechanisms.

• OpenC2 messages serialized in JSON MUST conform to the requirements of [RFC 7493] to support canonicalization.

• Digitally-signed OpenC2 messages serialized in JSON MUST be signed using JSON Signature Scheme in accordance with ITU-T X.590.

The method for message recipients to identify and validate the appropriate public key to validate a message signature is beyond the scope of this specification. Alternative, appropriate signature mechanisms will need to be specified for serializations other than JSON.

3.4 Type Definitions

3.4.1 Target Types

3.4.1.1 Artifact

Type: Artifact (Record{1..*})

Usage Requirements:

• An "Artifact" Target MUST contain at least one property.
• media_type "Artifact" property values SHOULD be interpreted according to the values documented in the IANA Media Types registry.

3.4.1.2 Device

Type: Device (Map{1..*})

Usage Requirement:

• A "Device" Target MUST contain at least one property.

3.4.1.3 Domain Name

3.4.1.4 Email Address

3.4.1.5 Features

Usage Requirements:

• A Producer MUST NOT send a list containing more than one instance of any Feature.

• A Consumer receiving a list containing more than one instance of any Feature SHOULD behave as if the duplicate(s) were not present.

• A Producer MAY send a 'query' Command containing an empty list of features. A Producer could do this to determine if a Consumer is responding to Commands (a heartbeat command) or to generate idle traffic to keep a connection to a Consumer from being closed due to inactivity (a keep-alive command). An active Consumer could return an empty response to this command, minimizing the amount of traffic used to perform heartbeat / keep-alive functions.

3.4.1.6 File

Type: File (Map{1..*})

Usage Requirement:

• A "File" Target MUST contain at least one property.

3.4.1.7 Internationalized Domain Name

3.4.1.8 Internationalized Email Address

3.4.1.9 IPv4 Address Range

An IPv4 address range is a CIDR block per "Classless Inter-domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan" [RFC4632] and consists of two values, an IPv4 address and a prefix.

For example, "192.168.17.0/24" is range of IP addresses with a prefix of 24 (i.e. 192.168.17.0 - 192.168.17.255).

Type: IPv4-Net (Array /ipv4-net)

Usage Requirements:

• JSON serialization of an IPv4 address range SHALL use the 'dotted/slash' textual representation of [RFC4632].

• CBOR serialization of an IPv4 address range SHALL use a binary representation of the IP address and the prefix, each in their own field.

3.4.1.10 IPv4 Connection

Type: IPv4-Connection (Record{1..*})

Usage Requirement:

• An "IPv4-Connection" MUST contain at least one property.

3.4.1.11 IPv6 Address Range

An IPv6 address range is a a block of contiguous IPv6 addresses, per "IP Version 6 Addressing Architecture" [RFC4291] and consists of two values, an IPv6 address and a prefix.

For example, "2001:0DB8:0000:CD30:0000:0000:0000:0000/60" is range of IPv6 addresses with a 60-bit prefix. Per Section 2.3 of RFC4291, the address portion may completely specify a node address (i.e., all 128-bits are meaningful) while the prefix value identifies the node's subnet.

Type: IPv6-Net (Array /ipv6-net)

Usage Requirements:

• JSON serialization of an IPv6 address range SHALL use the textual representation of IPv6 addresses and prefix lengths defined in [RFC4291].

• CBOR serialization of an IPv6 address range SHALL use a binary representation of the IP address and the prefix, each in their own field.

3.4.1.12 IPv6 Connection

Type: IPv6-Connection (Record{1..*})

Usage Requirement:

• An "IPv6-Connection" Target MUST contain at least one property.

3.4.1.13 IRI

3.4.1.14 MAC Address

3.4.1.15 Process

Type: Process (Map{1..*})

Usage Requirement:

• A "Process" Target MUST contain at least one property.

3.4.1.16 URI

3.4.2 Data Types

3.4.2.1 Action-Targets

3.4.2.2 Command-ID

Included in a Command message by an OpenC2 Producer to enable future references to the specific command. OpenC2 Consumers can include the command_id from the Command message in Responses to specify the Command to which the Response corresponds.

Usage Requirement:

• Value SHOULD be a string representation of a UUIDv4 as defined in [RFC4122].

3.4.2.3 Date-Time

Usage Requirement:

• Value is the number of milliseconds since 00:00:00 UTC, 1 January 1970

3.4.2.4 Duration

Usage Requirement:

• Value is a number of milliseconds

3.4.2.5 Feature

Specifies the results to be returned from a query features Command.

Type: Feature (Enumerated)

3.4.2.6 Hashes

Type: Hashes (Map{1..*})

Usage Requirement:

• A "Hashes" data type MUST contain at least one property.

3.4.2.7 Hostname

3.4.2.8 Internationalized Hostname

3.4.2.9 IPv4 Address

3.4.2.10 IPv6 Address

3.4.2.11 L4 Protocol

Value of the IPv4 "protocol" or IPv6 "next header" field in an IP packet. Recognized values for these fields are registered with IANA, according to the process defined in [RFC5237]. The table below identifies a non-exhaustive set of commonly used values.

Type: L4-Protocol (Enumerated)

Usage Requirements:

• The IPv4 Protocol field and IPv6 Next Header field are 8-bit values, therefore L4-Protocol is an enumeration from 0..255.
• Values of L4-Protocol SHOULD be interpreted as documented in [IANA_Protocols].

3.4.2.12 Message-Type

Identifies the type of Message.

Type: Message-Type (Enumerated)

3.4.2.13 Namespace Identifier

3.4.2.14 Payload

Type: Payload (Choice)

3.4.2.15 Port

Value of the port specified by a Layer 4 protocol, such as the source port in a TCP protocol header. Recognized values for these fields are registered with IANA, according to the process defined in [RFC6335].

Usage Requirements:

• The Port type is a 16-bit value, therefore provides an enumeration from 0..65535.
• Values of Port SHOULD be interpreted as documented in [IANA_Ports].

3.4.2.16 Response-Type

Type: Response-Type (Enumerated)

3.4.2.17 Targets

3.4.2.18 Version

Used to report the version(s) of OpenC2 supported by Consumers.

Usage Requirement:

• A Version string MUST contain the major and minor version numbers, represented as integers separated by a period (e.g., "1.1").

4 Mandatory Commands/Responses

The content in this section is normative, except where it is marked non-normative.

A Command consists of an Action/Target pair and associated Specifiers and Arguments. This section enumerates the allowed Commands, identifies which are required or optional to implement, and presents the associated responses.

4.1 Implementation of 'query features' Command

The 'query features' Command is REQUIRED for all Producers and Consumers implementing OpenC2. This section defines the REQUIRED and OPTIONAL aspects of the 'query features' Command and associated response for Producers and Consumers.

The 'query features' Command is REQUIRED for all Producers. The 'query features' Command MAY include one or more Features as defined in Section 3.4.2.5. The 'query features' Command MAY include the "response_requested": "complete" Argument. The 'query features' Command MUST NOT include any other Argument.

The 'query features' Command is REQUIRED for all Consumers. Consumers that receive and parse the 'query features':

• With any Argument other than "response_requested": "complete"

  • MUST NOT respond with OK/200.
  • SHOULD respond with Bad Request/400.
  • MAY respond with the 500 status code.

• With no Target Specifiers MUST respond with response code 200.

• With the "versions" Target Specifier MUST respond with status 200 and populate the versions field with a list of the OpenC2 Language Versions supported by the consumer.

• With the "profiles" Target Specifier MUST respond with status 200 and populate the profiles field with a list of profiles supported by the consumer.

• With the "pairs" Target Specifier MUST respond with status 200 and populate the pairs field with a list of action target pairs that define valid commands supported by the consumer.

• With the "rate_limit" Target Specifier populated:

  • SHOULD respond with status 200 and populate the rate_limit field with the maximum number of Commands per minute that the Consumer may support.

  • MAY respond with status 200 and with the rate_limit field unpopulated.

4.2 Examples of 'query features' Commands and Responses

This section is non-normative.

This sub-section provides examples of query features Commands and Responses. The examples provided in this section are for illustrative purposes only and are not to be interpreted as operational examples for actual systems.

4.2.1 Example 1: Bare "query : features"

There are no features specified in the query features Command. A simple "OK" Response Message is returned.

Command:

{
    "action": "query",
    "target": {
        "features": []
    }
}

Response:

{
    "status": 200
}

4.2.2 Example 2: Query for Specific Features

There are several features requested in the query features Command. All requested features can be returned in a single Response Message.

Command:

{
    "action": "query",
    "target": {
        "features": ["versions", "profiles", "rate_limit"]
    }
}

Response:

{
    "status": 200,
    "results": {
        "versions": ["1.1"],
        "profiles": ["slpf", "x-lock"],
        "rate_limit": 30
    }
}

4.2.3 Example 3: Query Features Detailed Response with Multiple Profiles

This example illustrates a response to the query features command from a Consumer that implements two Profiles: stateless packet filtering (slpf) and a notional blinky profile. The Command exercises the full range of query features options. Both profiles define custom targets:

• slpf defines the rule_number target
• blinky defines the device and display targets

This example illustrates the response to this mandatory command is split among aspects defined at the Consumer level and aspects defined at the individual Profile level. In a sense, the requirements of Section 4.1 of this specification constitute a base "profile" for the Consumer as a whole, and the results for versions, profiles, rate_limit and the basic "query": ["features"] appear in that portion of the response. The remaining content in the response is grouped by the two supported profiles.

Command:

{
  "action": "query",
  "target": {
    "features": ["versions", "profiles", "pairs", "rate_limit"]
  }
}

Response:

{
  "status": 200,
  "results": {
    "versions": ["1.1"],
    "profiles": ["slpf", "blinky"],
    "pairs": {
      "query": ["features"]
    },
    "rate_limit": 30,
    "slpf": {
      "pairs": {
        "allow": ["ipv6_net", "ipv6_connection"],
        "deny": ["ipv6_net", "ipv6_connection"],
        "delete": ["slpf/rule_number"],
        "update": ["file"]
      }
    },
    "blinky": {
      "pairs": {
        "query": ["blinky/device"],
        "set": ["blinky/display"]
      }
    }
  }
}

5 Conformance

This content in this section is normative.

5.1 Conformance Clause 1: Command

A conformant Command

• 5.1-1 MUST be structured in accordance with Section 3.3.1.

• 5.1-2 MUST include exactly one action property defined in accordance with Section 3.3.1.1.

• 5.1-3 MUST include exactly one target property defined in accordance with Section 3.3.1.2 or exactly one imported target property defined in accordance with Section 3.1.4.

• 5.1-4 MUST include zero or one profile property defined in accordance with Section 3.3.1.3.

• 5.1-5 MUST include zero or one args property defined in accordance with Section 3.3.1.4 or zero or one imported args property defined in accordance with Section 3.1.4.

5.2 Conformance Clause 2: Response

A conformant Response

• 5.2-1 MUST be structured in accordance with Section 3.3.2.

• 5.2-2 MUST include exactly one status property defined in accordance with Section 3.3.2.1.

5.3 Conformance Clause 3: Producer

A conformant Producer

• 5.3-1 MUST issue Commands and process Responses in accordance with Section 4.

• 5.3-2 MUST implement JSON serialization of generated Commands in accordance with [RFC7493].

• 5.3-3 MUST implement JSON deserialization of received Responses in accordance with [RFC7493].

5.4 Conformance Clause 4: Consumer

A conformant Consumer

• 5.4-1 MUST process Commands and issue Responses in accordance with Section 4.

• 5.4-2 MUST implement JSON serialization of generated Responses in accordance with [RFC7493].

• 5.4-3 MUST implement JSON deserialization of received Commands in accordance with [RFC7493].

Appendix A. References

This appendix contains the normative and informative references that are used in this document. Normative references are specific (identified by date of publication and/or edition number or version number) and Informative references are either specific or non-specific.

While any hyperlinks included in this appendix were valid at the time of publication, OASIS cannot guarantee their long-term validity.

A.1 Normative References

The following documents are referenced in such a way that some or all of their content constitutes requirements of this document.

[JADN-v1.0]

JSON Abstract Data Notation Version 1.0. Edited by David Kemp. 17 August 2021. OASIS Committee Specification 01. https://docs.oasis-open.org/openc2/jadn/v1.0/cs01/jadn-v1.0-cs01.html. Latest stage: https://docs.oasis-open.org/openc2/jadn/v1.0/jadn-v1.0.html.

[OpenC2-Arch-v1.0]

Open Command and Control (OpenC2) Architecture Specification Version 1.0. Edited by Duncan Sparrell. 30 September 2022. OASIS Committee Specification 01. https://docs.oasis-open.org/openc2/oc2arch/v1.0/cs01/oc2arch-v1.0-cs01.html. Latest stage: https://docs.oasis-open.org/openc2/oc2arch/v1.0/oc2arch-v1.0.html.

[OpenC2-HTTPS-v1.1]

Specification for Transfer of OpenC2 Messages via HTTPS Version 1.1. Edited by David Lemire. 30 November 2021. OASIS Committee Specification 01. https://docs.oasis-open.org/openc2/open-impl-https/v1.1/cs01/open-impl-https-v1.1-cs01.html. Latest stage: https://docs.oasis-open.org/openc2/open-impl-https/v1.1/open-impl-https-v1.1.html.

[OpenC2-MQTT-v1.0]

Specification for Transfer of OpenC2 Messages via MQTT Version 1.0. Edited by David Lemire. 19 November 2021. OASIS Committee Specification 01. https://docs.oasis-open.org/openc2/transf-mqtt/v1.0/cs01/transf-mqtt-v1.0-cs01.html. Latest stage: https://docs.oasis-open.org/openc2/transf-mqtt/v1.0/transf-mqtt-v1.0.html

[OpenC2-SLPF-v1.0]

Open Command and Control (OpenC2) Profile for Stateless Packet Filtering Version 1.0. Edited by Joe Brule, Duncan Sparrell, and Alex Everett. Latest version: http://docs.oasis-open.org/openc2/oc2slpf/v1.0/oc2slpf-v1.0.html

[RFC0768]

Postel, J., "User Datagram Protocol", STD 6, RFC 768, DOI 10.17487/RFC0768, August 1980, https://www.rfc-editor.org/info/rfc768.

[RFC0791]

Postel, J., "Internet Protocol", STD 5, RFC 791, DOI 10.17487/RFC0791, September 1981, https://www.rfc-editor.org/info/rfc791.

[RFC0792]

Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, DOI 10.17487/RFC0792, September 1981, https://www.rfc-editor.org/info/rfc792.

[RFC1034]

Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, https://www.rfc-editor.org/info/rfc1034.

[RFC1123]

Braden, R., Ed., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, DOI 10.17487/RFC1123, October 1989, https://www.rfc-editor.org/info/rfc1123.

[RFC1321]

Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, DOI 10.17487/RFC1321, April 1992, https://www.rfc-editor.org/info/rfc1321.

[RFC2119]

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, https://www.rfc-editor.org/info/rfc2119.

[RFC3444]

Pras, A., Schoenwaelder, J., "On the Difference between Information Models and Data Models", RFC 3444, January 2003, https://tools.ietf.org/html/rfc3444.

[RFC3986]

Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, https://www.rfc-editor.org/info/rfc3986.

[RFC3987]

Duerst, M. and M. Suignard, "Internationalized Resource Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987, January 2005, https://www.rfc-editor.org/info/rfc3987.

[RFC4122]

Leach, P., Mealling, M., and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, DOI 10.17487/RFC4122, July 2005, https://www.rfc-editor.org/info/rfc4122.

[RFC4291]

Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2006, https://www.rfc-editor.org/info/rfc4291.

[RFC4632]

Fuller, V. and T. Li, "Classless Inter-domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August 2006, https://www.rfc-editor.org/info/rfc4632.

[RFC4960]

Stewart, R., Ed., "Stream Control Transmission Protocol", RFC 4960, DOI 10.17487/RFC4960, September 2007, https://www.rfc-editor.org/info/rfc4960.

[RFC5237]

Arkko, J. and S. Bradner, "IANA Allocation Guidelines for the Protocol Field", BCP 37, RFC 5237, DOI 10.17487/RFC5237, February 2008, https://www.rfc-editor.org/info/rfc5237.

[RFC5322]

Resnick, P., Ed., "Internet Message Format", RFC 5322, DOI 10.17487/RFC5322, October 2008, https://www.rfc-editor.org/info/rfc5322.

[RFC5890]

Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework", RFC 5890, DOI 10.17487/RFC5890, August 2010, https://www.rfc-editor.org/info/rfc5890.

[RFC6234]

Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms (SHA and SHA-based HMAC and HKDF)", RFC 6234, DOI 10.17487/RFC6234, May 2011, https://www.rfc-editor.org/info/rfc6234.

[RFC6335]

Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. Cheshire, "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry", BCP 165, RFC 6335, DOI 10.17487/RFC6335, August 2011, https://www.rfc-editor.org/info/rfc6335.

[RFC6531]

Yao, J. and W. Mao, "SMTP Extension for Internationalized Email", RFC 6531, DOI 10.17487/RFC6531, February 2012, https://www.rfc-editor.org/info/rfc6531.

[RFC6838]

Freed, N., Klensin, J., and T. Hansen, "Media Type Specifications and Registration Procedures", BCP 13, RFC 6838, DOI 10.17487/RFC6838, January 2013, https://www.rfc-editor.org/info/rfc6838.

[RFC7493]

Bray, T., Ed., "The I-JSON Message Format", RFC 7493, DOI 10.17487/RFC7493, March 2015, https://www.rfc-editor.org/info/rfc7493.

[RFC8174]

Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, https://www.rfc-editor.org/info/rfc8174.

[RFC8200]

Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, https://www.rfc-editor.org/info/rfc8200.

[RFC8259]

Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, December 2017, https://www.rfc-editor.org/info/rfc8259.

[RFC9293]

Eddy, W., "Transmission Control Protocol (TCP)", RFC 9293, DOI: 10.17487/RFC9293, August 2022, https://www.rfc-editor.org/info/rfc9293.

[EUI]

"IEEE Registration Authority Guidelines for use of EUI, OUI, and CID", IEEE, August 2017, https://standards.ieee.org/content/dam/ieee-standards/standards/web/documents/tutorials/eui.pdf

[IEEE_RA]

"IEEE Registration Authority: Assignments", IEEE, August 2022, https://regauth.standards.ieee.org/standards-ra-web/pub/view.html#registries

[IANA_Ports]

"Internet Assigned Numbers Authority Service Name and Transport Protocol Port Number Registry", IANA, April 2024, https://www.iana.org/assignments/service-names-port-numbers/

[IANA_Protocols]

"Internet Assigned Numbers Authority Protocol Numbers", IANA, January 2024, https://www.iana.org/assignments/protocol-numbers

[IANA_Media]

"Internet Assigned Numbers Authority Media Types", IANA, April 2024, https://www.iana.org/assignments/media-types

[ITU-T X.590]

Recommendation ITU-T X.509 | ISO/IEC 9594-8 (2019), Information technology – Open Systems Interconnection – The Directory: Public-key and attribute certificate frameworks. JSON Signature Scheme (JSS), https://www.itu.int/rec/T-REC-X.590-202310-I

A.2 Informative References

[RFC3552]

Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on Security Considerations", BCP 72, RFC 3552, DOI 10.17487/RFC3552, July 2003, https://www.rfc-editor.org/info/rfc3552.

[IACD]

"What is IACD?", IACD, Integrated Adaptive Cyber Defense, 3/17/2018, https://www.iacdautomate.org/

[IM-JADN-v1.0]

Information Modeling with JADN Version 1.0. Edited by David Kemp. 19 April 2023. OASIS Committee Note 01. https://docs.oasis-open.org/openc2/imjadn/v1.0/cn01/imjadn-v1.0-cn01.html. Latest stage: https://docs.oasis-open.org/openc2/imjadn/v1.0/imjadn-v1.0.html.

[JSON-Schema]

"JSON Schema, a vocabulary that allows you to annotate and validate JSON documents.", retrieved 9/26/2022, https://json-schema.org/

[UML]

"Unified Modeling Language", Version 2.5.1, December 2017, https://www.omg.org/spec/UML/2.5.1/About-UML/

Appendix B. Safety, Security and Privacy Considerations

OpenC2, as a cyber defense automation tool, is high-value target for adversaries attempting to exploit an environment where it is used. Appendix B of the OpenC2 Architecture Specification [OpenC2-Arch-v1.0] discusses:

• Threats to OpenC2
• Applying security services to OpenC2 operations
• Network topology considerations for OpenC2 messages

Refer to that document for a review of these topics in the context of OpenC2.

Appendix C. Acknowledgments

The content in this section is non-normative.

C.1 Special Thanks

Substantial contributions to this document from the following individuals are gratefully acknowledged:

• Jason Romano, National Security Agency

C.2 Participants

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

OpenC2 TC Members:

Appendix D. Revision History

Appendix E. Examples

The content in this section is non-normative.

E.1 Example 1: Device Quarantine

This Command would be used to quarantine a device on the network.

{
    "action": "contain",
    "target": {
        "device": {
            "device_id": "9BCE8431AC106FAA3861C7E771D20E53"
        }
    }
}

E.2 Example 2: Block Connection

This Command blocks a particular connection within the domain. The standard Actuator Profile slpf defines the extended Command Argument drop_process. The Response is a simple acknowledgment that was requested in the Command arguments.

Command:

{
    "action": "deny",
    "target": {
        "ipv4_connection": {
            "protocol": "tcp",
            "src_addr": "1.2.3.4",
            "src_port": 10996,
            "dst_addr": "198.2.3.4",
            "dst_port": 80
        }
    },
    "args": {
        "start_time": 1534775460000,
        "duration": 500,
        "response_requested": "ack",
        "slpf": {
            "drop_process": "none"
        }
    },
    "profile": "slpf"
}

Response:

{
    "status": 102
}

Editor's Note: Replace with an example that does not use "properties".

Appendix F. Notices

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