SACM Working Group                                          A. Montville
Internet-Draft                                                 B. Munyan
Intended status: Standards Track                                     CIS
Expires: March 9, May 1, 2020                                September 06,                                    October 29, 2019

   Security Automation and Continuous Monitoring (SACM) Architecture
                        draft-ietf-sacm-arch-03
                        draft-ietf-sacm-arch-04

Abstract

   This memo document defines an architecture enabling a cooperative Security
   Automation and Continuous Monitoring (SACM) architecture. ecosystem.  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
   https://github.com/sacmwg/ietf-mandm-sacm-arch/.  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.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on March 9, May 1, 2020.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements notation . . . . . . . . . . . . . . . . . .   3
   2.  Terms and Definitions . . . . . . . . . . . . . . . . . . . .   3
   3.  Architectural Overview  . . . . . . . . . . . . . . . . . . .   3
     3.1.  Architectural Components  . .  SACM Role-based Architecture  . . . . . . . . . . . . . .   4
       3.1.1.  Orchestrator
     3.2.  Architectural Roles/Components  . . . . . . . . . . . . .   5
       3.2.1.  Orchestrator(s) . . . . . . .   5
       3.1.2.  Repositories/CMDBs . . . . . . . . . . . .   5
       3.2.2.  Repositories/CMDBs  . . . . .   5
       3.1.3.  Component Integration Service . . . . . . . . . . . .   5
     3.2.  Sub-Architectures . . .
       3.2.3.  Integration Service . . . . . . . . . . . . . . . . .   6   5
     3.3.  Downstream Uses . . . . . . . . . . . . . . . . . . . . .   6
       3.3.1.  Reporting . . . . . . . . . . . . . . . . . . . . . .   6
       3.3.2.  Analytics . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Sub-Architectural Components  . . . . . . . . . . .   6
     3.4.  Sub-Architectures . . . . .   7
     4.1.  Collection Sub-Architecture . . . . . . . . . . . . . . .   7
       4.1.1.  Posture
       3.4.1.  Collection Service  . . . . . . . . . Sub-Architecture . . . .   8
       4.1.2.  Endpoint . . . . . . . . .   7
       3.4.2.  Evaluation Sub-Architecture . . . . . . . . . . . . .   9
       4.1.3.  Posture Attribute Repository  . . . . . .
   4.  Interactions  . . . . . .   9
     4.2.  Evaluation Sub-Architecture . . . . . . . . . . . . . . .   9
       4.2.1.  Posture Evaluation Service . . .  11
   5.  Security Domain Workflows . . . . . . . . . .  10
       4.2.2.  Policy Repository . . . . . . . .  12
     5.1.  IT Asset Management . . . . . . . . . .  10
       4.2.3.  Evaluation Results Repository . . . . . . . . .  12
       5.1.1.  Components, Capabilities and Workflow(s)  . . .  11
   5.  Interactions . . .  13
     5.2.  Vulnerability Management  . . . . . . . . . . . . . . . .  13
       5.2.1.  Components, Capabilities and Workflow(s)  . . . . .  11
   6.  Security Domain Workflows .  14
     5.3.  Configuration Management  . . . . . . . . . . . . . . . .  15
       5.3.1.  Components, Capabilities and Workflow(s)  .  12
     6.1.  IT Asset Management . . . . .  16
   6.  Privacy Considerations  . . . . . . . . . . . . . .  12
     6.2.  Vulnerability Management . . . . .  18
   7.  Security Considerations . . . . . . . . . . .  13
     6.3.  Configuration Management . . . . . . . .  18
   8.  IANA Considerations . . . . . . . .  13
   7.  Configuration Management Components and Capabilities . . . .  14
     7.1.  Components . . . . . . . . .  18
   9.  References  . . . . . . . . . . . . . .  15
     7.2.  Capabilities . . . . . . . . . . .  19
     9.1.  Normative References  . . . . . . . . . . .  15
   8.  Configuration Assessment Workflow . . . . . . .  19
     9.2.  Informative References  . . . . . . .  15
   9.  Privacy Considerations . . . . . . . . . .  19
   Appendix A.  Mapping to RFC8248 . . . . . . . . .  17
   10. Security Considerations . . . . . . . .  21
   Appendix B.  Example Components . . . . . . . . . . .  17
   11. IANA Considerations . . . . . .  24
     B.1.  Policy Services . . . . . . . . . . . . . . .  17
   12. References . . . . . .  24
     B.2.  Software Inventory  . . . . . . . . . . . . . . . . . . .  18
     12.1.  Normative References  25
     B.3.  Datastream Collection . . . . . . . . . . . . . . . . . .  18
     12.2.  Informative References  26
     B.4.  Network Configuration Collection  . . . . . . . . . . . .  26
   Appendix C.  Exploring An XMPP-based Solution . . . . .  18
   Appendix A.  Mapping to RFC8248 . . . . .  27
     C.1.  Example Architecture using XMPP-Grid and Endpoint Posture
           Collection Protocol . . . . . . . . . . . .  20
   Appendix B.  Example Components . . . . . . .  30
   Authors' Addresses  . . . . . . . . . .  23
     B.1.  Policy Services . . . . . . . . . . . . . . . . . . . . .  23
     B.2.  Software Inventory  . . . . . . . . . . . . . . . . . . .  24
     B.3.  Datastream Collection . . . . . . . . . . . . . . . . . .  25
     B.4.  Network Configuration Collection  . . . . . . . . . . . .  25
   Appendix C.  Exploring An XMPP-based Solution . . . . . . . . . .  25
     C.1.  Example Architecture using XMPP-Grid and Endpoint Posture
           Collection Protocol . . . . . . . . . . . . . . . . . . .  29
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  31  32

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.

          +----------------+
          | SACM Component |
          |   (Provider)   |
          +-------+--------+
                  |
                  |
   +--------------v----------------+
   |      Integration Service      |
   +--------------+----------------+
                  |
                  |
          +-------v--------+
          | SACM Component |
          |   (Consumer)   |
          +----------------+

                  Figure 1: Basic Architectural Structure

   A provider can be described as an abstraction that refers to an
   entity capable of sending SACM-relevant information to one or many
   consumers.  Consumers can be described as an abstraction that refers
   to an entity capable of receiving SACM-relevant information from one
   or many providers.  Different roles within a cooperative ecosystem
   may act as both providers and consumers of SACM-relevant information.

3.1.  SACM Role-based Architecture

   Within the cooperative SACM ecosystem, a number of roles act in
   coordination to provide relevant policy/guidance, perform data
   collection, storage, evaluation, and support downstream analytics and
   reporting.

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

                Figure 1: 2: Notional Role-based Architecture

   As shown in Figure 1, 2, the SACM role-based architecture consists of
   some basic SACM Components communicating using a component an 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) point-to-point) and
   proxied data exchange.

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

3.1.

3.2.  Architectural Components Roles/Components

   This document suggests a variety of players in a cooperative
   ecosystem - we call
   ecosystem; these players are known as 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  Roles may act as providers of information information, consumers of
   information, or a both provider
   of information.  The and consumer.  Figure 1 diagram illustrates 2 depicts a
   number of SACM components which are architecturally significant and
   therefore warrant discussion and clarification.

3.1.1.  Orchestrator

   An

3.2.1.  Orchestrator(s)

   Orchestration component components 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.

3.2.2.  Repositories/CMDBs

   The

   Figure 1 diagram 2 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

3.2.3.  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
   services are woven together.  The Component Integration Service acts as a
   message broker, combining a canonical data model, a set of common command set, message categories 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 various information payloads, orchestration of
   component 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.
   SACM components will "attach" to the Integration Service either
   through native support for the integration implementation, or through
   the use of "adapters" which provide a proxied attachment.

   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 Integration Service MUST provide 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 for
   payloads between producers and Evaluation. consumers.  The following section, Architectural
   Workflows (TBD - ADD LINK) Integration Service
   MAY provide further expands on capabilities within the payload delivery
   pipeline.  Examples of these components/
   workflows. capabilities include, but are not
   limited to, intermediate processing, message transformation, type
   conversion, validation, etc.

3.3.  Downstream Uses

   As depicted by Figure 1, 2, 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 outside of the SACM
   architecture scope 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 outside of the SACM
   architecture scope 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

3.4.  Sub-Architectures

   Figure 2 shows two sub-architectures depicted components representing sub-architectural roles
   involved in the Figure 1: a cooperative ecosystem of SACM components: Collection
   and Evaluation.

4.1.

3.4.1.  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                    Orchestrator(s)                       |
   +-----------+----------------------------------------------+
               |               +------------------------------+
               |               | Posture Attribute Repository |
               |               +--------------^---------------+
            Perform                           |                              |
               |
           Collection                         |
               |                       Collected Data
               |                              ^
               |                              |
   +-----------v------------------------------+---------------+
   |             Component                    Integration Service                   |
   +----+------------------^-----------+------------------^---+
        |                  |           |                  |
        |                  |           |                  |
        v                  |           v                  |
     Perform           Collected    Perform           Collected
    Collection           Data      Collection           Data
        |                  ^           |                  ^
        |                  |           |                  |
        |                  |           |                  |
   +----v------------------+----+ +----v------------------+----+
   +----v-----------------------+ +----v------------------+------+
   | Posture Collection Service | | Posture Collection Service          Endpoint            |
   +---^------------------------+ | +--------------------------+ |
       |                   |      | +------------------------+ |Posture Collection Service| |
       |                   v      | |        Endpoint        | +--------------------------+ |
     Events             Queries   | +------------------------+ |   +------------------------------+
       ^                   |      +----------------------------+
       |                   |
   +---+-------------------v----+
   |          Endpoint          |
   +----------------------------+

             Figure 2: 3: Decomposed Collection Sub-Architecture

4.1.1.

3.4.1.1.  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.

3.4.1.2.  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.

3.4.1.3.  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.

3.4.1.4.  Posture Collection Workflow

   Posture collection may be triggered from a number of components, but
   commonly begin either via event-based triggering on an endpoint or
   through manual orchestration, both illustrated in Figure 3 above.
   Once orchestration has provided the directive to perform collection,
   posture collection services consume the directives.  Posture
   collection is invoked for those endpoints overseen by the respective
   posture collection services.  Collected data is then provided to the
   Integration Service, with a directive to store that information in an
   appropriate repository.

3.4.2.  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

                     +------------------+
                     |
+-------------------+-------------------+    Collection    |    +-------------------------------+
                     | Sub-Architecture |
+-------------------v-------------------+    |     Component Integration Service Evaluation Results Repository |
+--------+------------^--------^--------+
+--------------+     +--------^---------+    +-----------------^-------------+
| Orchestrator |              |                                |
+------+-------+              |                                |
         v
       |    Retrieve         +--------------------------------+                   Perform         |     Posture <-------+  Posture Attribute Repository                 Store Evaluation Results
    Perform               Collection                           |
   Evaluation                 |    Attributes       +--------------------------------+                                |
       |                      |                                |
+------v----------------------v--------------------------------+-------------+
|                             Integration Service                            |
+--------+----------------------------^----------------------^---------------+
         |                     +--------------------------------+                            |            +-----Retrieve <------+        Policy Repository                      |
         |                            |                      |
      Perform                  Retrieve Posture              |
     Evaluation                   Attributes          Retrieve Policy         +--------------------------------+
         |
+--------v------------------------------+                            |                      |
         |                            |                      |
+--------v-------------------+  +-----v------+        +------v-----+
| Posture Evaluation Service |
+----------------------------+----------+  |
                             v
                         Evaluation
                          Results  Posture   |        |
        +--------------------v----------+   Policy   |
+----------------------------+  | Attribute  |        | Evaluation Results Repository |
        +-------------------------------+
                                | Repository |        +------------+
                                +------------+

             Figure 3: 4: Decomposed Evaluation Sub-Architecture

4.2.1.

3.4.2.1.  Posture Evaluation Service

   The Posture Evaluation Service (PES) 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.

3.4.2.2.  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.

3.4.2.3.  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.

3.4.2.4.  Posture Evaluation Workflow

   Posture evaluation is orchestrated through the Integration Service to
   the appropriate Posture Evaluation Service.  The PES will, through
   coordination with the Integration Service, query both the Posture
   Attribute Repository and the Policy Repository to obtain relevant
   state data for comparison.  If necessary, the PES may be required to
   invoke further posture collection.  Once all relevant posture
   information has been collected, it is compared to expected state
   based on applicable policy.  Comparison results are then persisted to
   an evaluation results repository for further downstream use and
   analysis.

4.  Interactions

   SACM Components are intended to interact with other SACM Components.
   These interactions can be thought of, at the level of this architectural approach, level, 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 sub-domain-specific
   characteristics and instructions.

   Two categories of interactions SHOULD be supported by the Integration
   Service; broadcast interactions, and directed interactions.

   o  *Publish/Subscribe*:  *Broadcast*: A broadcast interaction, commonly known as "publish/
      subscribe", allows for a wider distribution of a message payload.
      When a payload is published to a topic on the Integration Service,
      all subscribers to that topic are alerted and may consume the
      message payload.  A broadcast interaction may also simulate a
      "directed" interaction when a topic only has a single subscriber.
      An example of a broadcast interaction could be to publish to a
      topic that new configuration assessment content is available.
      Subscribing consumers receive the notification, and proceed to
      collect endpoint configuration posture based on the new content.

   o  *Directed*: The intent of a directed interaction is to enable
      point-to-point communications between a producer and consumer,
      through the standard interfaces provided by the Integration
      Service.  The provider component publishes information indicates which consumer is
      intended to a
      messaging system receive the payload, and a set of other components, subscribed the Integration Service
      routes the payload directly to that
      information type, receive consumer.  Two "styles" of
      directed interaction exist, differing only by the published information.

   o  *Request/Response*: A response from
      the payload consumer:

      *  *Synchronous (Request/Response)*: Synchronous, request/response
         style interaction can take a
      number of forms, but will always be synchronous operations
      involving requires that the requesting component waiting/blocking until a
      response is received from block
         and wait for the requested receiving component to respond, or a timeout
      occurs.

      *  *Information Request*: An information request to time out
         when that response is simply one
         component requesting information from another component, such
         as an Orchestrator requesting collection capabilities from delayed past a
         Posture Collection Service.

      *  *Query*: given time threshold.  A query
         synchronous interaction can take one of two forms,
         "selection" or "storage".

         +  _Selection_: A component requests data from a repository.

         +  _Storage_: A component provides data to example may be persisted in querying a
            repository.

   o  *Directive*: Commonly referred CMDB for
         posture attribute information in order to as "Send-and-Forget", a
      directive is perform an
         evaluation.

      *  *Asynchronous (Fire-and-Forget)*: An asynchronous interaction whereby
         involves the payload producer directing the message to a component
      requests information from another component
         consumer, but does not wait/
      block blocking or waiting for a response.  This
         style of interaction allows the producer to continue on to
         other activities without the need to wait for responses.  This
         style is particularly useful when the interaction payload
         invokes a potentially long-running task, such as data
         collection, report generation, or policy evaluation.  The
         receiving component may reply later via callbacks or further
         interactions, but it is not mandatory.

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

6. instructions to
   be interpreted by receiving components.

5.  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.

5.1.  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. virtual, on-premises or in the cloud.

5.1.1.  Components, Capabilities and Workflow(s)

   TBD

5.1.1.1.  Components

   TBD

5.1.1.2.  Capabilities

   An IT asset management capability needs to be able to:

   o  Identify and catalog new assets by executing Target Endpoint
      Discovery Tasks

   o  Provide information about its managed assets, including uniquely
      identifying information (for that enterprise)

   o  Handle software and/or hardware (including virtual assets)

   o  Represent cloud hybrid environments

6.2.

5.1.1.3.  Workflow(s)

   TBD

5.2.  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:

   o  Endpoint information collected by the endpoint management
      capabilities is examined by the vulnerability management
      capabilities through Evaluation Tasks.

   o  If the data possessed by the endpoint management capabilities is
      insufficient, a Collection Task is triggered and the necessary
      data is collected from the target endpoint.

   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:

   o  A specific software version is installed on the endpoint

   o  File system attributes

   o  Specific state attributes

   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.

5.2.1.  Components, Capabilities and Workflow(s)

   TBD

5.2.1.1.  Components

   TBD

5.2.1.2.  Capabilities

   TBD

5.2.1.3.  Workflow(s)

   TBD

5.3.  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:

   o  Reputable source publishes new or updated configuration guidance

   o  Enterprise configuration assessment capability retrieves
      configuration guidance from reputable source

   o  Optional: Configuration guidance is tailored for enterprise-
      specific needs

   o  Configuration assessment tool queries asset inventory repository
      to retrieve a list of affected endpoints

   o  Configuration assessment tool queries configuration state
      repository to evaluate compliance

   o  If information is stale or unavailable, configuration assessment
      tool triggers an ad hoc assessment

   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

5.3.1.  Components, Capabilities and Workflow(s)

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

7.1.

5.3.1.1.  Components

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

   o  Configuration Policy Feed: An external source of authoritative
      configuration recommendations.

   o  Configuration Policy Repository: An internal repository of
      enterprise standard configurations.

   o  Configuration Assessment Orchestrator: A component responsible for
      orchestrating assessments.

   o  Posture Attribute Collection Subsystem: A component responsible
      for collection of posture attributes from systems.

   o  Posture Attribute Repository: A component used for storing system
      posture attribute values.

   o  Configuration Assessment Evaluator: A component responsible for
      evaluating system posture attribute values against expected
      posture attribute values.

   o  Configuration Assessment Results Repository: A component used for
      storing evaluation results.

7.2.

5.3.1.2.  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.

5.3.1.3.  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  |   +----------------------------------------+  Orchestrator  |  |    Evaluation    |
+-----v------+  2   +----------------+  5  +-----v-----+  6   +------------+  |   Policy   +------>  Orchestrator  +-----> Evaluator +------> Evaluation |
+------+------+  +-------+--------+  | Sub-Architecture |  |   Results  |
       |                 |           +---^----------+---+  | Repository |
       |                 |               |          |      +------^-----+
       |                 |               |          |             |
     1.|               3.|             8.|        9.|          10.|
       |                 |               |          |             |
       |                 |               |          | Repository             |      +-------+--------+     +-----^-----+
+------v-----------------v---------------+----------v-------------+-----+
|   Results                           Integration Service                         |
+------------+
+-----+----------------------------------+----------^---------+------^--+
      |                                  |          | Repository         |      | 3
      |            +------------+                                  |          | 5.2
                 +----------|--------+         |      | +--------v------+
    2.|                                4.|        5.|       6.|    7.|
      |                                  |          |         |   Collector      |
      |                                  |          | +-------+-------+         |   4   +------------+      |
+-----v------+                       +---v----------+---+  +--v------+--+
|         +-------> Posture   Policy   |                       | +-------+-------+    Collection    |  | Attribute  Posture   |
| Repository | Target System                       | Sub-Architecture |  | Repository Attribute  |
+------------+                       +------------------+  | +---------------+ Repository |
                                                           +------------+
                 +-------------------+
              Collection Sub-Architecture

         Figure 4: 5: Configuration Assessment Component Interactions

   Figure 4 5 depicts configuration assessment components and their
   interactions, which are further described below.

   1.  Policy is stored in   A policy feed provides a configuration assessment policy payload
        to the Policy Repository: TODO - add specific
       interaction options here. Integration Service.

   2.   The Orchestrator obtains collection information from Policy Repository, a consumer of Policy Feed information,
        receives and persists the Policy
       Repository: TODO - add specific interaction options here. Feed's payload.

   3.  The Orchestrator initiates collection   Orchestration component(s), either manually invoked, scheduled,
        or event-based, publish a payload to begin the configuration
        assessment process.

   4.   If necessary, Collection Sub-Architecture components may be performed by
        invoked to collect neeeded posture attribute information.

   5.   If necessary, the Collection Sub-Architecture: TODO - add specific interaction
       options here.

   4.  Collected Sub-Architecture will provide
        collected posture attributes are stored n to the Integration Service for
        persistence to the Posture Attribute
       Repository: TODO - add specific interaction options here.

   5. Repository.

   6.   The Orchestrator initiates Posture Attribute Repository will consume a payload querying
        for relevant posture attribute information.

   7.   The Posture Attribute Repository will provide the Evaluator (optionally with
       evaluation requested
        information gathered from to the Policy Repository): TODO
       - add specific interaction options here

       1. Integration Service, allowing further
        orchestration payloads requesting the Evaluation Sub-
        Architecture perform evaluation tasks.

   8.   The Evaluator obtains Evaluation Sub-Architecture consumes the evaluation information from payload
        and performs component-specific state comparison operations to
        produce evaluation results.

   9.   A payload containing evaluation results are provided by the Policy
           Repository (optionally): TODO - add specific interaction
           options here

       2.  The Evaluator obtains relevant posture attributes from
        Evaluation Sub-Architecture to the
           Posture Attribute Repository: TODO - add specific interaction
           options here

   6. Integration Service

   10.  Evaluation results are stored in consumed by/persisted to the Evaluation
        Results
       Repository: TODO - add specific interaction options here Repository

   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 a directed 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.

6.  Privacy Considerations

   TODO

10.

7.  Security Considerations

   TODO

11.

8.  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:

   o  Capability/operation semantics

   o  SACM Component implementation identifiers
   o  SACM Component versions

   o  Associations of SACM Components (and versions) to specific
      Capabilities

   o  Collection sub-architecture Identification

12.

9.  References

12.1.

9.1.  Normative References

   [I-D.ietf-sacm-ecp]
              Haynes, D., Fitzgerald-McKay, J., and L. Lorenzin,
              "Endpoint Posture Collection Profile", draft-ietf-sacm-
              ecp-05 (work in progress), 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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [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,
              <https://www.rfc-editor.org/info/rfc8412>.

   [RFC8600]  Cam-Winget, N., Ed., 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,
              <https://www.rfc-editor.org/info/rfc8600>.

12.2.

9.2.  Informative References

   [CISCONTROLS]
              "CIS Controls v7.0", n.d.,
              <https://www.cisecurity.org/controls>.

   [draft-birkholz-sacm-yang-content]
              Birkholz, H. and N. Cam-Winget, "YANG subscribed
              notifications via SACM Statements", n.d.,
              <https://tools.ietf.org/html/
              draft-birkholz-sacm-yang-content-01>.
              <https://tools.ietf.org/html/draft-birkholz-sacm-yang-
              content-01>.

   [HACK100]  "IETF 100 Hackathon - Vulnerability Scenario EPCP+XMPP",
              n.d., <https://www.github.com/sacmwg/vulnerability-
              scenario/ietf-hackathon>.

   [HACK101]  "IETF 101 Hackathon - Configuration Assessment XMPP",
              n.d., <https://www.github.com/CISecurity/Integration>.

   [HACK102]  "IETF 102 Hackathon - YANG Collection on Traditional
              Endpoints", n.d.,
              <https://www.github.com/CISecurity/YANG>.

   [HACK103]  "IETF 103 Hackathon - N/A", n.d.,
              <https://www.ietf.org/how/meetings/103/>.

   [HACK104]  "IETF 104 Hackathon - A simple XMPP client", n.d.,
              <https://github.com/CISecurity/SACM-Architecture>.

   [HACK105]  "IETF 105 Hackathon - A more robust XMPP client including
              collection extensions", n.d.,
              <https://github.com/CISecurity/SACM-Architecture>.

   [HACK99]   "IETF 99 Hackathon - Vulnerability Scenario EPCP", n.d.,
              <https://www.github.com/sacmwg/vulnerability-scenario/
              ietf-hackathon>.

   [I-D.ietf-sacm-terminology]
              Birkholz, H., Lu, J., Strassner, J., Cam-Winget, N., and
              A. Montville, "Security Automation and Continuous
              Monitoring (SACM) Terminology", draft-ietf-sacm-
              terminology-16 (work in progress), 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,
              <https://csrc.nist.gov/publications/detail/sp/800-126/rev-
              3/final>.

   [NISTIR7694]
              Halbardier, A., Waltermire, D., and M. Johnson, "NISTIR
              7694 Specification for Asset Reporting Format 1.1", n.d.,
              <https://csrc.nist.gov/publications/detail/nistir/7694/
              final>.

   [RFC5023]  Gregorio, J., Ed. and B. de hOra, Ed., "The Atom
              Publishing Protocol", RFC 5023, DOI 10.17487/RFC5023,
              October 2007, <https://www.rfc-editor.org/info/rfc5023>.

   [RFC7632]  Waltermire, D. and D. Harrington, "Endpoint Security
              Posture Assessment: Enterprise Use Cases", RFC 7632,
              DOI 10.17487/RFC7632, September 2015,
              <https://www.rfc-editor.org/info/rfc7632>.

   [RFC8248]  Cam-Winget, N. and L. Lorenzin, "Security Automation and
              Continuous Monitoring (SACM) Requirements", RFC 8248,
              DOI 10.17487/RFC8248, September 2017,
              <https://www.rfc-editor.org/info/rfc8248>.

   [RFC8322]  Field, J., Banghart, S., and D. Waltermire, "Resource-
              Oriented Lightweight Information Exchange (ROLIE)",
              RFC 8322, DOI 10.17487/RFC8322, February 2018,
              <https://www.rfc-editor.org/info/rfc8322>.

   [XMPPEXT]  "XMPP Extensions", n.d., <https://xmpp.org/extensions/>.

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:

   o  N/A: The requirement is not applicable to this architectural
      exploration

   o  Architecture: This architecture (possibly assuming some
      components) should meet the requirement

   o  XMPP: The set of XMPP Core specifications and the collection of
      applicable extensions, deployment, and operational considerations.

   o  XMPP-Core: The requirement is satisfied by a core XMPP feature

   o  XEP-nnnn: The requirement is satisfied by a numbered XMPP
      extension (see [XMPPEXT])

   o  Operational: The requirement is an operational concern or can be
      addressed by an operational deployment

   o  Implementation: The requirement is an implementation concern

   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: 6: EPCP Collection Architecture

   In Figure 5, 6, 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:

   o  [HACK99]: A partial implementation of a vulnerability assessment
      scenario involving an [I-D.ietf-sacm-ecp] implementation, a
      [RFC8322] implementation, and a proprietary evaluator to pull the
      pieces together.

   o  [HACK100]: Work to combine the vulnerability assessment scenario
      from [HACK99] with an XMPP-based YANG push model.

   o  [HACK101]: A fully automated configuration assessment
      implementation using XMPP (specifically Publish/Subscribe
      capabilities) as a communication mechanism.

   o  [HACK102]: An exploration of how we might model assessment,
      collection, and evaluation abstractly, and then rely on YANG
      expressions for the attributes of traditional endpoints.

   o  [HACK103]: No SACM participation at the Bangkok hackathon.

   o  [HACK104]: Basic XMPP-to-Concise MAP - Created an XMPP adapter
      that can accept basic posture attributes and translate them to
      Concise MAP.  This hackathon only proved the concept that system
      characteristics information can be transported via XMPP and
      translated to a (very basic) concise MAP implementation.

   o  [HACK105]: Advanced XMPP-to-Concise MAP: Full orchestration of
      collection capabilities using XMPP.  Collector implementations
      extend the core XMPP structure to allow OVAL collection
      instructions (OVAL objects) to inform posture attribute
      collection.  Collected system characteristics can be provided to
      the Concise MAP XMPP adapter using all 3 available XMPP
      capabilities: Publish/Subscribe, Information Query (iq - request/
      response) stanzas, or direct Message stanzas.  CDDL was created to
      map collected posture attributes to Concise MAP structure.  The
      XMPP adapter translates the incoming system characteristics and
      stores the information in the MAP.

   Figure 6 7 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, 7, 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 7 may be a provider, a consumer, or both,
   depending on the workflow in context.

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

                     Figure 6: 7: XMPP-based Architecture

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

   o  Service Discovery (XEP-0030): Service Discovery allows XMPP
      entities to discover information about other XMPP entities.  Two
      kinds of information can be discovered: the identity and
      capabilities of an entity, such as supported features, and items
      associated with an entity.

   o  Publish-Subscribe (XEP-0060): The PubSub extension enables
      entities to create nodes (topics) at a PubSub service and publish
      information at those nodes.  Once published, an event notification
      is broadcast to all entities that have subscribed to that node.

   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 7 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:

   o  Entity Capabilities (XEP-0115): This extension defines the methods
      for broadcasting and dynamically discovering an entities'
      capabilities.  This information is transported via standard XMPP
      presence.  Example capabilities that could be discovered could
      include support for posture attribute collection, support for
      specific types of posture attribute collection such as EPCP,
      SWIMA, OVAL, or YANG.  Other capabilities are still to be
      determined.

   o  Ad Hoc Commands (XEP-0050): This extension allows an XMPP entity
      to advertise and execute application-specific commands.  Typically
      the commands contain data forms (XEP-0004) in order to structure
      the information exchange.  This extension may be usable for simple
      orchestration (i.e. "do assessment").

   o  HTTP File Upload (XEP-0363): The HTTP File Upload extension allows
      for large data sets to be published to a specific path on an HTTP
      server, and receive a URL from which that file can later be
      downloaded again.  XMPP messages and IQs are meant to be compact,
      and large data sets, such as collected posture attributes, may
      exceed a message size threshold.  Usage of this XEP allows those
      larger data sets to be persisted, thus necessitating only the
      download URL to be passed via XMPP messages.

   o  Personal Eventing Protocol (XEP-0163): The Personal Eventing
      Protocol can be thought of as a virtual PubSub service, allowing
      an XMPP account to publish events only to their roster instead of
      a generic PubSub topic.  This XEP may be useful in the cases when
      collection requests or queries are only intended for a subset of
      endpoints and not an entire subscriber set.

   o  File Repository and Sharing (XEP-0214): This extension defines a
      method for XMPP entities to designate a set of file available for
      retrieval by other users of their choosing, and is based on PubSub
      Collections.

   o  Easy User Onboarding (XEP-401): The goal of this extension is
      simplified client registration, and may be useful when adding new
      endpoints or SACM components to the ecosystem.

   o  Bidirectional-streams Over Synchronous HTTP (BOSH) (XEP-0124):
      BOSH emulates the semantics of a long-lived, bidirectional TCP
      connection between two entities (aka "long polling").  Consider a
      SACM component that is updated dynamically, i.e. an internal
      vulnerability definition repository ingesting data from a Feed/
      Repository of External Data, and a second SACM component such as
      an Orchestrator.  Using BOSH, the Orchestrator can effectively
      continuously poll the vulnerability definition repository for
      changes/updates.

   o  PubSub Collection Nodes (XEP-0248): Effectively an extension to
      XEP-0060 (Publish-Subscribe), PubSub Collections aim to simplify
      an entities' subscription to multiple related topics, and
      establishes a "node graph" relating parent nodes to its
      descendents.  An example "node graph" could be rooted in a
      "vulnerability definitions" topic, and contain descendent topics
      for OS family-level vulnerability definitions (i.e.  Windows), and
      further for OS family version-level definitions (i.e.  Windows 10
      or Windows Server 2016).

   o  PubSub Since (XEP-0312): This extension enables a subscriber to
      automatically receive PubSub and Personal Eventing Protocol (PEP)
      notifications since its last logout time.  This extension may be
      useful in intermittent connection scenarios, or when entities
      disconnect and reconnect to the ecosystem.

   o  PubSub Chaining (XEP-0253): This extension describes the
      federation of publishing nodes, enabling a publish node of one
      server to be a subscriber to a publishing node of another server.

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

   Figure 7 8 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
********************v*********************** Boundary ************ of Responsibility *******
*                   |                                                         *
*  +--------------+ | +-------------------+ +-------------+                   *
*  | 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: 8: XMPP-based Architecture including EPCP

Authors' Addresses

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

   Email: adam.montville.sdo@gmail.com

   Bill Munyan
   Center for Internet Security
   31 Tech Valley Drive
   East Greenbush, NY  12061
   USA

   Email: bill.munyan.ietf@gmail.com