SACM Working Group A. Montville
Internet-Draft B. Munyan
Intended status: Standards Track CIS
Expires: March 9, 2020 September 06, 2019

Security Automation and Continuous Monitoring (SACM) Architecture


This memo defines a Security Automation and Continuous Monitoring (SACM) architecture. This work is built upon [RFC8600], and is predicated upon information gleaned from SACM Use Cases and Requirements ([RFC7632] and [RFC8248] respectively), and terminology as found in [I-D.ietf-sacm-terminology].

WORKING GROUP: The source for this draft is maintained in GitHub. Suggested changes should be submitted as pull requests at Instructions are on that page as well.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on March 9, 2020.

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Table of Contents

1. Introduction

The purpose of this draft is to define an architectural approach for a SACM Domain, based on the spirit of use cases found in [RFC7632] and requirements found in [RFC8248]. This approach gains the most advantage by supporting a variety of collection systems, and intends to enable a cooperative ecosystem of tools from disparate sources with minimal operator configuration.

1.1. Requirements notation

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 RFC 2119, BCP 14 [RFC2119].

2. Terms and Definitions

This draft defers to [I-D.ietf-sacm-terminology] for terms and definitions.

3. Architectural Overview

The generic approach proposed herein recognizes the need to obtain information from existing and future state collection systems, and makes every attempt to respect [RFC7632] and [RFC8248]. At the foundation of any architecture are entities, or components, that need to communicate. They communicate by sharing information, where, in a given flow, one or more components are consumers of information and one or more components are providers of information.

              | Feeds/Repositories |
              |  of External Data  |
****************************************************** Enterprise Boundary ***
      +--------------+  |  +--------------------+
      | Orchestrator |  |  | Repositories/CMDBs |
      +------^-------+  |  +----------^---------+
             |          |             |             +--------------------+
             |          |             |             |  Downstream Uses   |
             |          |             |             | +----------------+ |
 +-----------v----------v-------------v------+      | |   Analytics    | |
 |       Component Integration Service       <------> +----------------+ |
 +----- -----^--------------------------^----+      | +----------------+ |
             |                          |           | |   Reporting    | |
             |                          |           | +----------------+ |
 +-----------v-------------------+      |           +--------------------+
 |  Collection Sub-Architecture  |      |
 +-------------------------------+      |
                  |  Evaluation Sub-Architecture  |

Figure 1: Notional Architecture

As shown in Figure 1, the SACM architecture consists of some basic SACM Components communicating using a component integration service. The component integration service is expected to maximally align with the requirements described in [RFC8248], which means that the component integration service will support brokered (i.e. point-to-point) and proxied data exchange.

The enterprise boundary is not intended to imply a physical boundary. Rather, the enterprise boundary is intended to be inclusive of various cloud environments and vendor-provided services in addition to any physical systems the enterprise operates.

3.1. Architectural Components

This document suggests a variety of players in a cooperative ecosystem - we call these players SACM Components. SACM Components may be composed of other SACM Components, and each SACM Component plays one, or more, of several roles relevant to the ecosystem. Generally each role is either a consumer of information or a provider of information. The Figure 1 diagram illustrates a number of SACM components which are architecturally significant and therefore warrant discussion and clarification.

3.1.1. Orchestrator

An Orchestration component exists to aid in the automation of configuration, coordination, and management for the ecosystem of SACM components. The Orchestrator performs control-plane operations, administration of an implementing organization's components (including endpoints, posture collection services, and downstream activities), scheduling of automated tasks, and any ad-hoc activities such as the initiation of collection or evaluation activities. The Orchestrator is the key administrative interface into the SACM architecture.

3.1.2. Repositories/CMDBs

The Figure 1 diagram only includes a single reference to "Repositories/CMDBs", but in practice, a number of separate data repositories may exist, including posture attribute repositories, policy repositories, local vulnerability definition data repositories, and state assessment results repositories. These data repositories may exist separately or together in a single representation, and the design of these repositories may be as distinct as their intended purpose, such as the use of relational database management systems or graph/map implementations focused on the relationships between data elements. Each implementation of a SACM repository should focus on the relationships between data elements and implement the SACM information and data model(s).

3.1.3. Component Integration Service

If each SACM component represents a set of services, capabilities, and/or functions, the Component Integration Service represents the "fabric" by which all those services, capabilities and functions are woven together. The Component Integration Service acts as a message broker, combining a canonical data model, a common command set, and a messaging infrastructure to allow other SACM components to communicate using a shared set of interfaces. The Component Integration Service's brokering capabilities enable the exchange of information, the orchestration of capabilities, message routing and reliable delivery. The Component Integration Service minimizes the dependencies from one system to another through the loose coupling of applications through messaging.

The Component Integration Service should provide mechanisms for synchronous "request/response"-style messaging, asynchronous "send and forget" messaging, or publish/subscribe. It is the responsibility of the Component Integration Service to coordinate and manage the sending and receiving of messages. The Component Integration Service should allow components the ability to directly connect and produce or consume messages, or connect via message translators which can act as a proxy, transforming messages from a component format to one implementing a SACM data model.

A number of pieces come together to form the Component Integration Service:

  1. Common communication infrastructure: The physical communications infrastructure, providing a cross-platform, cross-language universal adapter between SACM components. This infrastructure commonly includes message routing capabilities to facilitate the correct routing of messages from SACM component to SACM component, as well as using Publish/Subscribe functionality to facilitate sending messages to all receivers.
  2. Adapters: The use of a standard, canonical data model will likely require SACM components to translate component-specific information into the canonical format used by the message broker.
  3. Common command/interaction structure: Just as PC architectures have a common set of commands to represent the different operations possible on a physical bus, there must be common interactions that all SACM components can understand.

3.2. Sub-Architectures

The Figure 1 shows two components representing the architectural workflows involved in a cooperative ecosystem of SACM components: Collection and Evaluation. The following section, Architectural Workflows (TBD - ADD LINK) further expands on these components/workflows.

3.3. Downstream Uses

As depicted by Figure 1, a number of downstream uses exist in the cooperative ecosystem. Each notional SACM component represents distinct sub-architectures which will exchange information via the component integration services, using interactions described in this draft.

3.3.1. Reporting

The Reporting component represents the capabilities of the SACM architecture dealing with the query and retrieval of collected posture attribute information, evaluation results, etc. in various display formats that are useful to a wide range of stakeholders.

3.3.2. Analytics

The Analytics component represents the capabilities of the SACM architecture dealing with the discovery, interpretation, and communication of any meaningful patterns of data in order to inform effective decision making within the organization.

4. Sub-Architectural Components

This section describes the workflows derived from the interactions with the two sub-architectures depicted in the Figure 1: Collection and Evaluation.

4.1. Collection Sub-Architecture

The Collection sub-architecture, in a SACM context, is the mechanism by which posture attributes are collected from applicable endpoints and persisted to a repository, such as a configuration management database (CMDB). Orchestration components will choreograph endpoint data collection via interactions using the Component Integration Service as a message broker. Instructions to perform endpoint data collection are directed to a Posture Collection Service capable of performing collection activities utilizing any number of methods, such as SNMP, NETCONF/RESTCONF, SSH, WinRM, or host-based.

|                       Orchestrator                       |
            |               +------------------------------+
            |               | Posture Attribute Repository |
            |               +--------------^---------------+
            |                              |
            |                              |
            |                       Collected Data
            |                              ^
            |                              |
|             Component Integration Service                |
     |                  |           |                  |
     |                  |           |                  |
     v                  |           v                  |
  Perform           Collected    Perform           Collected
 Collection           Data      Collection           Data
     |                  ^           |                  ^
     |                  |           |                  |
     |                  |           |                  |
+----v------------------+----+ +----v------------------+----+
| Posture Collection Service | | Posture Collection Service |
+---^------------------------+ |                            |
    |                   |      | +------------------------+ |
    |                   v      | |        Endpoint        | |
  Events             Queries   | +------------------------+ |
    ^                   |      +----------------------------+
    |                   |
|          Endpoint          |

Figure 2: Collection Sub-Architecture

4.1.1. Posture Collection Service

The Posture Collection Service (PCS) is the SACM component responsible for the collection of posture attributes from an endpoint or set of endpoints. A single PCS may be responsible for management of posture attribute collection from many endpoints. The PCS will interact with the Component Integration Service to receive collection instructions and to provide collected posture data for persistence to the Posture Attribute Repository. Collection instructions may be supplied in a variety of forms, including subscription to a publish/subscribe topic to which the Component Integration Service has published instructions, via request/response-style synchronous messaging, or via asynchronous "send-and-forget" messaging. Collected posture information may then be supplied to the Component Integration Service via similar channels. The various interaction types are discussed later in this draft (TBD).

4.1.2. Endpoint

Building upon [I-D.ietf-sacm-terminology], the SACM Collection Sub-Architecture augments the definition of an Endpoint as a component within an organization's management domain from which a Posture Collection Service will collect relevant posture attributes.

4.1.3. Posture Attribute Repository

The Posture Attribute Repository is a SACM component responsible for the persistent storage of posture attributes collected via interactions between the Posture Collection Service and Endpoints.

4.2. Evaluation Sub-Architecture

The Evaluation Sub-Architecture, in the SACM context, is the mechanism by which policy, expressed in the form of expected state, is compared with collected posture attributes to yield an evaluation result, that result being contextually dependent on the policy being evaluated.

|              Orchestrator             |
|     Component Integration Service     |
         |            |        |
         |            |        |
         v            |    Retrieve         +--------------------------------+
      Perform         |     Posture <-------+  Posture Attribute Repository  |
     Evaluation       |    Attributes       +--------------------------------+
         |            |
         |            |
         |            |                     +--------------------------------+
         |            +-----Retrieve <------+        Policy Repository       |
         |                   Policy         +--------------------------------+
|       Posture Evaluation Service      |
        | Evaluation Results Repository |

Figure 3: Evaluation Sub-Architecture

4.2.1. Posture Evaluation Service

The Posture Evaluation Service represents the SACM component responsible for coordinating the policy to be evaluated and the collected posture attributes relevant to that policy, as well as the comparison engine responsible for correctly determining compliance with the expected state.

4.2.2. Policy Repository

The Policy Repository represents a persistent storage mechanism for the policy to be assessed against collected posture attributes to determine if an endpoint meets the defined expected state. Examples of information contained in a Policy Repository would be Vulnerability Definition Data or configuration recommendations as part of a CIS Benchmark or DISA STIG.

4.2.3. Evaluation Results Repository

The Evaluation Results Repository persists the information representing the results of a particular posture assessment, indicating those posture attributes collected from various endpoints which either meet or do not meet the expected state defined by the assessed policy. Consideration should be made for the context of individual results. For example, meeting the expected state for a configuration attribute indicates a correct configuration of the endpoint, whereas meeting an expected state for a vulnerable software version indicates an incorrect and therefore vulnerable configuration.

5. Interactions

SACM Components are intended to interact with other SACM Components. These interactions can be thought of, at the level of this architectural approach, as the combination of interfaces with their supported operations. Each interaction will convey a payload of information. The payload information is expected to contain sub-domain-specific characteristics and instructions.

Each interaction will convey a payload of information. The payload information is expected to contain sub-domain-specific characteristics and instructions.

6. Security Domain Workflows

This section describes three primary information security domains from which workflows may be derived: IT Asset Management, Vulnerability Management, and Configuration Management.

6.1. IT Asset Management

Information Technology asset management is easier said than done. The [CISCONTROLS] have two controls dealing with IT asset management. Control 1, Inventory and Control of Hardware Assets, states, "Actively manage (inventory, track, and correct) all hardware devices on the network so that only authorized devices are given access, and unauthorized and unmanaged devices are found and prevented from gaining access." Control 2, Inventory and Control of Software Assets, states, "Actively manage (inventory, track, and correct) all software on the network so that only authorized software is installed and can execute, and that unauthorized and unmanaged software is found and prevented from installation or execution."

In spirit, this covers all of the processing entities on your network (as opposed to things like network cables, dongles, adapters, etc.), whether physical or virtual.

An IT asset management capability needs to be able to:

6.2. Vulnerability Management

Vulnerability management is a relatively established process. To paraphrase the [CISCONTROLS], continuous vulnerability management is the act of continuously acquiring, assessing, and taking subsequent action on new information in order to identify and remediate vulnerabilities, therefore minimizing the window of opportunity for attackers.

A vulnerability assessment (i.e. vulnerability detection) is performed in two steps:

Vulnerability detection relies on the examination of different endpoint information depending on the nature of a specific vulnerability. Common endpoint information used to detect a vulnerability includes:

In some cases, the endpoint information needed to determine an endpoint's vulnerability status will have been previously collected by the endpoint management capabilities and available in a Repository. However, in other cases, the necessary endpoint information will not be readily available in a Repository and a Collection Task will be triggered to perform collection from the target endpoint. Of course, some implementations of endpoint management capabilities may prefer to enable operators to perform this collection even when sufficient information can be provided by the endpoint management capabilities (e.g. there may be freshness requirements for information).

6.3. Configuration Management

Configuration management involves configuration assessment, which requires state assessment. The [CISCONTROLS] specify two high-level controls concerning configuration management (Control 5 for non-network devices and Control 11 for network devices). As an aside, these controls are listed separately because many enterprises have different organizations for managing network infrastructure and workload endpoints. Merging the two controls results in the following paraphrasing: Establish, implement, and actively manage (track, report on, correct) the security configuration of systems using a rigorous configuration management and change control process in order to prevent attackers from exploiting vulnerable services and settings.

Typically, an enterprise will use configuration guidance from a reputable source, and from time to time they may tailor the guidance from that source prior to adopting it as part of their enterprise standard. The enterprise standard is then provided to the appropriate configuration assessment tools and they assess endpoints and/or appropriate endpoint information.

A preferred flow follows:

The SACM architecture needs to support varying deployment models to accommodate the current state of the industry, but should strongly encourage event-driven approaches to monitoring configuration.

7. Configuration Management Components and Capabilities

This section provides more detail about the components and capabilities required when considering the aforementioned configuration management workflow.

7.1. Components

The following is a minimal list of SACM Components required to implement the aforementioned configuration assessment workflow.

7.2. Capabilities

Per [RFC8248], solutions MUST support capability negotiation. Components implementing specific interfaces and operations (i.e. interactions) will need a method of describing their capabilities to other components participating in the ecosystem; for example, "As a component in the ecosystem, I can assess the configuration of Windows, MacOS, and AWS using OVAL".

8. Configuration Assessment Workflow

This section describes the components and interactions in a basic configuration assessment workflow. For simplicity, error conditions are recognized as being necessary and are not depicted. When one component messages another component, the message is expected to be handled appropriately unless there is an error condition, or other notification, messaged in return.

| Policy Feed |
      |                     5.1
  1   |   +----------------------------------------+
      |   |                                        |            
+-----v------+  2   +----------------+  5  +-----v-----+  6   +------------+
|   Policy   +------>  Orchestrator  +-----> Evaluator +------> Evaluation |
| Repository |      +-------+--------+     +-----^-----+      |   Results  |
+------------+              |                    |            | Repository |
                            | 3                  |            +------------+
                            |                    | 5.2
                 +----------|--------+           |
                 | +--------v------+ |           |
                 | |   Collector   | |           |
                 | +-------+-------+ |   4   +------------+
                 |         |         +-------> Posture    |
                 | +-------+-------+ |       | Attribute  |
                 | | Target System | |       | Repository |
                 | +---------------+ |       +------------+
              Collection Sub-Architecture

Figure 4: Configuration Assessment Component Interactions

Figure 4 depicts configuration assessment components and their interactions, which are further described below.

  1. Policy is stored in the Policy Repository: TODO - add specific interaction options here.
  2. The Orchestrator obtains collection information from the Policy Repository: TODO - add specific interaction options here.
  3. The Orchestrator initiates collection to be performed by the Collection Sub-Architecture: TODO - add specific interaction options here.
  4. Collected posture attributes are stored n the Posture Attribute Repository: TODO - add specific interaction options here.
  5. The Orchestrator initiates the Evaluator (optionally with evaluation information gathered from the Policy Repository): TODO - add specific interaction options here
    1. The Evaluator obtains evaluation information from the Policy Repository (optionally): TODO - add specific interaction options here
    2. The Evaluator obtains relevant posture attributes from the Posture Attribute Repository: TODO - add specific interaction options here
  6. Evaluation results are stored in the Evaluation Results Repository: TODO - add specific interaction options here

In the above flow, the payload information is expected to convey the context required by the receiving component for the action being taken under different circumstances. For example, the Tell message sent from an Orchestrator to a Collection sub-architecture might be telling that Collector to watch a specific posture attribute and report only specific detected changes to the Posture Attribute Repository, or it might be telling the Collector to gather that posture attribute immediately. Such details are expected to be handled as part of that payload, not as part of the architecture described herein.

9. Privacy Considerations


10. Security Considerations


11. IANA Considerations

TODO: Revamp this section after the configuration assessment workflow is fleshed out.

IANA tables can probably be used to make life a little easier. We would like a place to enumerate:

12. References

12.1. Normative References

[I-D.ietf-sacm-ecp] Haynes, D., Fitzgerald-McKay, J. and L. Lorenzin, "Endpoint Posture Collection Profile", Internet-Draft draft-ietf-sacm-ecp-05, June 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC8412] Schmidt, C., Haynes, D., Coffin, C., Waltermire, D. and J. Fitzgerald-McKay, "Software Inventory Message and Attributes (SWIMA) for PA-TNC", RFC 8412, DOI 10.17487/RFC8412, July 2018.
[RFC8600] Cam-Winget, N., Appala, S., Pope, S. and P. Saint-Andre, "Using Extensible Messaging and Presence Protocol (XMPP) for Security Information Exchange", RFC 8600, DOI 10.17487/RFC8600, June 2019.

12.2. Informative References

[CISCONTROLS] "CIS Controls v7.0", n.d..
[draft-birkholz-sacm-yang-content] Birkholz, H. and N. Cam-Winget, "YANG subscribed notifications via SACM Statements", n.d..
[HACK100] "IETF 100 Hackathon - Vulnerability Scenario EPCP+XMPP", n.d..
[HACK101] "IETF 101 Hackathon - Configuration Assessment XMPP", n.d..
[HACK102] "IETF 102 Hackathon - YANG Collection on Traditional Endpoints", n.d..
[HACK103] "IETF 103 Hackathon - N/A", n.d..
[HACK104] "IETF 104 Hackathon - A simple XMPP client", n.d..
[HACK105] "IETF 105 Hackathon - A more robust XMPP client including collection extensions", n.d..
[HACK99] "IETF 99 Hackathon - Vulnerability Scenario EPCP", n.d..
[I-D.ietf-sacm-terminology] Birkholz, H., Lu, J., Strassner, J., Cam-Winget, N. and A. Montville, "Security Automation and Continuous Monitoring (SACM) Terminology", Internet-Draft draft-ietf-sacm-terminology-16, December 2018.
[NIST800126] Waltermire, D., Quinn, S., Booth, H., Scarfone, K. and D. Prisaca, "SP 800-126 Rev. 3 - The Technical Specification for the Security Content Automation Protocol (SCAP) - SCAP Version 1.3", February 2018.
[NISTIR7694] Halbardier, A., Waltermire, D. and M. Johnson, "NISTIR 7694 Specification for Asset Reporting Format 1.1", n.d..
[RFC5023] Gregorio, J. and B. de hOra, "The Atom Publishing Protocol", RFC 5023, DOI 10.17487/RFC5023, October 2007.
[RFC7632] Waltermire, D. and D. Harrington, "Endpoint Security Posture Assessment: Enterprise Use Cases", RFC 7632, DOI 10.17487/RFC7632, September 2015.
[RFC8248] Cam-Winget, N. and L. Lorenzin, "Security Automation and Continuous Monitoring (SACM) Requirements", RFC 8248, DOI 10.17487/RFC8248, September 2017.
[RFC8322] Field, J., Banghart, S. and D. Waltermire, "Resource-Oriented Lightweight Information Exchange (ROLIE)", RFC 8322, DOI 10.17487/RFC8322, February 2018.
[XMPPEXT] "XMPP Extensions", n.d..

Appendix A. Mapping to RFC8248

TODO: Consider removing or placing in a separate solution draft.

This section provides a mapping of XMPP and XMPP Extensions to the relevant requirements from [RFC8248]. In the table below, the ID and Name columns provide the ID and Name of the requirement directly out of [RFC8248]. The Supported By column may contain one of several values:

If there is no entry in the Supported By column, then there is a gap that must be filled.

ID Name Supported By
G-001 Solution Extensibility XMPP-Core
G-002 Interoperability XMPP
G-003 Scalability XMPP
G-004 Versatility XMPP-Core
G-005 Information Extensibility XMPP-Core
G-006 Data Protection Operational
G-007 Data Partitioning Operational
G-008 Versioning and Backward Compatibility XEP-0115/0030
G-009 Information Discovery XEP-0030
G-010 Target Endpoint Discovery XMPP-Core
G-011 Push and Pull Access XEP-0060/0312
G-012 SACM Component Interface N/A
G-013 Endpoint Location and Network Topology
G-014 Target Endpoint Identity XMPP-Core
G-015 Data Access Control
ARCH-001 Component Functions XMPP
ARCH-002 Scalability XMPP-Core
ARCH-003 Flexibility XMPP-Core
ARCH-004 Separation of Data and Management Functions
ARCH-005 Topology Flexibility XMPP-Core
ARCH-006 Capability Negotiation XEP-0115/0030
ARCH-007 Role-Based Authorization XMPP-Core
ARCH-008 Context-Based Authorization
ARCH-009 Time Synchronization Operational
IM-001 Extensible Attribute Vocabulary N/A
IM-002 Posture Data Publication N/A
IM-003 Data Model Negotiation N/A
IM-004 Data Model Identification N/A
IM-005 Data Lifetime Management N/A
IM-006 Singularity and Modularity N/A
DM-001 Element Association N/A
DM-002 Data Model Structure N/A
DM-003 Search Flexibility N/A
DM-004 Full vs. Partial Updates N/A
DM-005 Loose Coupling N/A
DM-006 Data Cardinality N/A
DM-007 Data Model Negotiation N/A
DM-008 Data Origin N/A
DM-009 Origination Time N/A
DM-010 Data Generation N/A
DM-011 Data Source N/A
DM-012 Data Updates N/A
DM-013 Multiple Collectors N/A
DM-014 Attribute Extensibility N/A
DM-015 Solicited vs. Unsolicited Updates N/A
DM-016 Transfer Agnostic N/A
OP-001 Time Synchronization
OP-002 Collection Abstraction
OP-003 Collection Composition
OP-004 Attribute-Based Query
OP-005 Information-Based Query with Filtering
OP-006 Operation Scalability
OP-007 Data Abstraction
OP-008 Provider Restriction
T-001 Multiple Transfer Protocol Support Architecture
T-002 Data Integrity Operational
T-003 Data Confidentiality Operational
T-004 Transfer Protection
T-005 Transfer Reliability
T-006 Transfer-Layer Requirements
T-007 Transfer Protocol Adoption Architecture

Appendix B. Example Components

TODO: Consider removing.

B.1. Policy Services

Consider a policy server conforming to [RFC8322]. [RFC8322] describes a RESTful way based on the ATOM Publishing Protocol ([RFC5023]) to find specific data collections. While this represents a specific binding (i.e. RESTful API based on [RFC5023]), there is a more abstract way to look at ROLIE.

ROLIE provides notional workspaces and collections, and provides the concept of information categories and links. Strictly speaking, these are logical concepts independent of the RESTful binding ROLIE specifies. In other words, ROLIE binds a logical interface (i.e. GET workspace, GET collection, SET entry, and so on) to a specific mechanism (namely an ATOM Publication Protocol extension).

It is not inconceivable to believe there could be a different interface mechanism, or a connector, providing these same operations using XMPP-Grid as the transfer mechanism.

Even if a [RFC8322] server were external to an organization, there would be a need for a policy source inside the organization as well, and it may be preferred for such a policy source to be connected directly to the ecosystem's communication infrastructure.

B.2. Software Inventory

The SACM working group has accepted work on the Endpoint Posture Collection Profile [I-D.ietf-sacm-ecp], which describes a collection architecture and may be viewed as a collector coupled with a collection-specific repository.

                                 Posture Manager              Endpoint
                Orchestrator    +---------------+        +---------------+
                +--------+      |               |        |               |
                |        |      | +-----------+ |        | +-----------+ |
                |        |<---->| | Posture   | |        | | Posture   | |
                |        | pub/ | | Validator | |        | | Collector | |
                |        | sub  | +-----------+ |        | +-----------+ |
                +--------+      |      |        |        |      |        |
                                |      |        |        |      |        |
Evaluator       Repository      |      |        |        |      |        |
+------+        +--------+      | +-----------+ |<-------| +-----------+ |
|      |        |        |      | | Posture   | | report | | Posture   | |
|      |        |        |      | | Collection| |        | | Collection| |
|      |<-----> |        |<-----| | Manager   | | query  | | Engine    | |
|      |request/|        | store| +-----------+ |------->| +-----------+ |
|      |respond |        |      |               |        |               |
|      |        |        |      |               |        |               |
+------+        +--------+      +---------------+        +---------------+

Figure 5: EPCP Collection Architecture

In Figure 5, any of the communications between the Posture Manager and EPCP components to its left could be performed directly or indirectly using a given message transfer mechanism. For example, the pub/sub interface between the Orchestrator and the Posture Manager could be using a proprietary method or using [RFC8600] or some other pub/sub mechanism. Similarly, the store connection from the Posture Manager to the Repository could be performed internally to a given implementation, via a RESTful API invocation over HTTPS, or even over a pub/sub mechanism.

Our assertion is that the Evaluator, Repository, Orchestrator, and Posture Manager all have the potential to represent SACM Components with specific capability interfaces that can be logically specified, then bound to one or more specific transfer mechanisms (i.e. RESTful API, [RFC8322], [RFC8600], and so on).

B.3. Datastream Collection

[NIST800126], also known as SCAP 1.3, provides the technical specifications for a "datastream collection". The specification describes the "datastream collection" as being "composed of SCAP data streams and SCAP source components". A "datastream" provides an encapsulation of the SCAP source components required to, for example, perform configuration assessment on a given endpoint. These source components include XCCDF checklists, OVAL Definitions, and CPE Dictionary information. A single "datastream collection" may encapsulate multiple "datastreams", and reference any number of SCAP components. Datastream collections were intended to provide an envelope enabling transfer of SCAP data more easily.

The [NIST800126] specification also defines the "SCAP result data stream" as being conformant to the Asset Reporting Format specification, defined in [NISTIR7694]. The Asset Reporting Format provides an encapsulation of the SCAP source components, Asset Information, and SCAP result components, such as system characteristics and state evaluation results.

What [NIST800126]did not do is specify the interface for finding or acquiring source datastream information, nor an interface for publishing result information. Discovering the actual resources for this information could be done via ROLIE, as described in the Policy Services section above, but other repositories of SCAP data exist as well.

B.4. Network Configuration Collection

[draft-birkholz-sacm-yang-content] illustrates a SACM Component incorporating a YANG Push client function and an XMPP-grid publisher function. [draft-birkholz-sacm-yang-content] further states "the output of the YANG Push client function is encapsulated in a SACM Content Element envelope, which is again encapsulated in a SACM statement envelope" which are published, essentially, via an XMPP-Grid Connector for SACM Components also part of the XMPP-Grid.

This is a specific example of an existing collection mechanism being adapted to the XMPP-Grid message transfer system.

Appendix C. Exploring An XMPP-based Solution

TODO: Consider removing or placing in a separate draft.

Ongoing work has been taking place around and during IETF hackathons. The list of hackathon efforts follows:

Figure 6 depicts a slightly more detailed view of the architecture (within the enterprise boundary) - one that fosters the development of a pluggable ecosystem of cooperative tools. Existing collection mechanisms can be brought into this architecture by specifying the interface of the collector and creating the XMPP-Grid Connector binding for that interface.

Additionally, while not directly depicted in Figure 6, this architecture does allow point-to-point interfaces. In fact, [RFC8600] provides brokering capabilities to facilitate such point-to-point data transfers). Additionally, each of the SACM Components depicted in Figure 6 may be a provider, a consumer, or both, depending on the workflow in context.

 +--------------+           +--------------+
 | Orchestrator |           | Repositories |
 +------^-------+           +------^-------+       
        |                          |
        |                          |
+-------v--------------------------v--------+     +-----------------+
|                XMPP-Grid+                 <-----> Downstream Uses |
+------------------------^------------------+     +-----------------+
                 |  XMPP-Grid   |   
                 | Connector(s) |
                 | Collector(s) |

Figure 6: XMPP-based Architecture

[RFC8600] details a number of XMPP extensions (XEPs) that MUST be utilized to meet the needs of [RFC7632] and [RFC8248]:

At this point, [RFC8600] specifies fewer features than SACM requires, and there are other XMPP extensions (XEPs) we need to consider to meet the needs of [RFC7632] and [RFC8248]. In Figure 6 we therefore use "XMPP-Grid+" to indicate something more than [RFC8600] alone, even though we are not yet fully confident in the exact set of XMPP-related extensions we will require. The authors propose work to extend (or modify) [RFC8600] to include additional XEPs - possibly the following:

C.1. Example Architecture using XMPP-Grid and Endpoint Posture Collection Protocol

Figure 7 depicts a further detailed view of the architecture including the Endpoint Posture Collection Protocol as the collection subsystem, illustrating the idea of a pluggable ecosystem of cooperative tools.

          | Feeds/Repositories |
          |  of External Data  |
********************v************************* Enterprise Boundary ************
*                   |                                                         *
*  +--------------+ | +-------------------+ +-------------+                   *
*  | Orchestrator | | | Posture Attr Repo | | Policy Repo |                   *
*  +------^-------+ | +---------^---------+ +---^---------+                   *
*         |         |           |               |          +----------------+ *
*         |         |           |               |          | Downstream Uses| *
*         |         |           |               |          | +-----------+  | *
*  +------v---------v-----------v---------------v--+       | |Evaluations|  | *
*  |                    XMPP-Grid                  <-------> +-----------+  | *
*  +----------------^-------------------^----------+       | +-----------+  | *
*                   |                   |                  | | Analytics |  | *
*                   |                   |                  | +-----------+  | *
*                   |             +-----v--------+         | +-----------+  | *
*                   |             | Results Repo |         | | Reporting |  | *
*                   |             +--------------+         | +-----------+  | *
*                   |                                      +----------------+ *
*         +---------v-----------+                                             *
*         | XMPP-Grid Connector |                                             *
*         +---------^-----------+                                             *
*                   |                                                         *
* +-----------------v-------------------------------------------------------+ *
* |                                                                         | *
* | +--Posture Collection Manager------------------------------------------+| *
* | |+-----------------------+ +----------------+ +----------------------+ || *
* | || Communications Server | | Posture Server | | Posture Validator(s) | || *
* | |+----------^------------+ +----------------+ +----------------------+ || *
* | +-----------|----------------------------------------------------------+| *
* |             |                                                           | *
* | +-----------|-------------------------Endpoint or Endpoint Proxy-------+| *
* | |+----------v------------+ +----------------+ +----------------------+ || *
* | || Communications Client | | Posture Client | | Posture Collector(s) | || *
* | |+-----------------------+ +----------------+ +----------------------+ || *
* | +----------------------------------------------------------------------+| *
* +-----------------Endpoint Posture Collection Profile---------------------+ *
*                                                                             *

Figure 7: XMPP-based Architecture including EPCP

Authors' Addresses

Adam W. Montville Center for Internet Security 31 Tech Valley Drive East Greenbush, NY 12061 USA EMail:
Bill Munyan Center for Internet Security 31 Tech Valley Drive East Greenbush, NY 12061 USA EMail: