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Versions: 00 01 02 03 04 05                                             
SACM                                                  N. Cam-Winget, Ed.
Internet-Draft                                             Cisco Systems
Intended status: Informational                               L. Lorenzin
Expires: April 18, 2016                                     Pulse Secure
                                                             I. McDonald
                                                          High North Inc
                                                               A. Woland
                                                           Cisco Systems
                                                        October 16, 2015

    Secure Automation and Continuous Monitoring (SACM) Architecture


   This document defines an architecture for standardization of
   interfaces, protocols, and information models related to security
   automation and continuous monitoring.  It describes the basic
   architecture, components, and interfaces defined to enable the
   collection, acquisition, and verification of Posture and Posture

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 18, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Architectural Overview  . . . . . . . . . . . . . . . . . . .   3
     3.1.  Component Roles . . . . . . . . . . . . . . . . . . . . .   5
       3.1.1.  Provider  . . . . . . . . . . . . . . . . . . . . . .   6
       3.1.2.  Consumer  . . . . . . . . . . . . . . . . . . . . . .   7
       3.1.3.  Types of Providers and Consumers  . . . . . . . . . .   8  Collector . . . . . . . . . . . . . . . . . . . .   8  Evaluator . . . . . . . . . . . . . . . . . . . .   9  Report Generator  . . . . . . . . . . . . . . . .   9  Data Store  . . . . . . . . . . . . . . . . . . .   9
       3.1.4.  Controller  . . . . . . . . . . . . . . . . . . . . .   9
   4.  Interfaces between Consumers, Providers, and Controllers  . .  11
   5.  Component Functions . . . . . . . . . . . . . . . . . . . . .  12
     5.1.  Control Plane Functions . . . . . . . . . . . . . . . . .  12
     5.2.  Data Plane Functions  . . . . . . . . . . . . . . . . . .  14
   6.  Component Capabilities  . . . . . . . . . . . . . . . . . . .  15
   7.  Example Illustration of Functions and Workflow  . . . . . . .  15
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  18
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  18
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  19
     11.2.  Informative References . . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   Several data models and protocols (including - but not limited to -
   NEA, TCG TNC, SCAP, SWIDs, XMPP, etc.) are in use today that allow
   different applications to perform the collection, acquisition, and
   assessment of posture.  These applications can vary from being
   focused on general system and security management to specialized
   configuration, compliance, and control systems.  With an existing
   varied set of applications, there is a strong desire to standardize
   data models, protocols, and interfaces to better allow for the
   automation of such data processes.

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   This document addresses general and architectural requirements
   defined in [I-D.ietf-sacm-requirements].  The architecture described
   enables standardized collection, acquisition, and verification of
   Posture and Posture Assessments.  This architecture includes the
   components and interfaces that can be used to better identify the
   Information Model and type(s) of transport protocols needed for

   This document uses terminology defined in

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

   When the words appear in lower case, their natural language meaning
   is used.

2.  Problem Statement

   Securing information and the systems that store, process, and
   transmit that information is a challenging task for organizations of
   all sizes, and many security practitioners spend much of their time
   on manual processes.  Administrators can't get technology from
   disparate sources to work together; they need information to make
   decisions, but the information is not available.  Everyone is
   collecting the same data, but storing it as different information.
   Administrators therefore need to collect data and craft their own
   information, which may not be accurate or interoperable because it's
   customized by each administrator, not shared.

   Security automation and continuous monitoring require a large and
   broad set of mission and business processes; to make the most
   effective use of technology, the same data must support multiple
   processes.  The need for complex characterization and assessment
   necessitates components and functions that interoperate and can build
   off each other to enable far-ranging and/or deep-diving analysis.
   SACM is standardizing an information model, data models, operations,
   and transports that will allow for administrators to share with
   others and to use data from others interoperably.

3.  Architectural Overview

   At a high level, the SACM architecture describes "Where" and "How"
   information and assessment of posture may be collected, processed
   (e.g. normalization, translation, aggregation, etc.), assessed,

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   exchanged, and/or stored.  This section provides an architectural
   overview of

   o  the basic architectural building blocks, which - in combination -
      constitute SACM components (the entities, the "where"), and

   o  the relationships and interaction between these building blocks on
      the data plane and control plane (communications and flows between
      entities, the "how").

   The SACM architecture provides the basic means to describe and
   compose SACM components.  Components enable the basic functionality
   in SACM, such as Endpoint Attribute Collection or Target Endpoint
   Posture Assessment.

   The role(s) a component plays in the SACM architecture are determined
   by the function(s) that component instantiates.  Three main component
   roles are defined: a Consumer (Cs), a Provider (Pr), and a Controller
   (Cr) used to facilitate some of the security functions such as
   authentication and authorization and other metadata functions.  See
   Section 3.1 for details on roles.

   In SACM, components are composed of functions, the modular building
   blocks in the SACM architecture.  The SACM architecture defines the
   purpose of these functions.  Attributes and operations used by
   component functions are described in other SACM documents.  See
   Section 5 for details on component functions.

   Functions use SACM interfaces for communications between components.
   Interfaces handle management and control functions (such as
   authentication, authorization, registration, and discovery), and
   enable SACM components to share information (via publication, query,
   and subscription).  Three primary interfaces are defined: an
   interface for management and control (A), an interface for data
   communication between the controller and providers or consumers (B),
   and an interface for data communication directly between a provider
   and a consumer (C).  See Section 4 for details on interfaces.

   Figure 1 illustrates the relationships between component roles and

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                         | +--------------------------------------+
                         | | +--------------------------------------+
                         | | |                                      |
                         +-| |            Consumer (Cs)             |
                           +-|                                      |
                               /   \         /   \            /   \
                              /     \       /     \          /     \
                              -     -       -  d  -          -     -
                               || ||A        | a  |B          |   |C
                               || ||         | t  |           |   |
                              -     -       -  a  -           |   |
                              \     /       \     /           |   |
                               \   /         \   /            |   |
                            /|---------------------|\         |   |
                     /|----/                         \--------| d |--|\
                    /     /      Controller (Cr)      \ ctrl  | a |    \
                    \     \                           / plane | t |    /
                     \|----\                         /--------| a |--|/
                            \|---------------------|/         |   |
                               /   \         /   \            |   |
                              /     \       /     \           |   |
                              -     -       -  d  -           |   |
                               || ||A        | a |B           |   |C
                               || ||         | t |            |   |
                              -     -       -  a  -          -     -
                              \     /       \     /          \     /
                               \   /         \   /            \   /
                             |                                    |-+
                             |            Provider (Pr            | |
                             |                                    | |-+
                             +------------------------------------+ | |
                               +------------------------------------+ |

                   Figure 1: Simple Architectural Model

3.1.  Component Roles

   An endpoint, as defined in [I-D.ietf-sacm-terminology], can operate
   in two primary ways: as the target of an assessment, and/or as a
   functional component of the SACM architecture that can instantiate
   one or more functions (see Section 5).  In the SACM architecture,

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   individual endpoints may be a target endpoint, a component, or both
   simultaneously.  An endpoint acting as a component may perform one or
   more roles.  Components can take on the role(s) of Provider,
   Consumer, and/or Controller.

3.1.1.  Provider

   The Provider (Pr) is the component that contributes Posture
   Assessment Information and/or Guidance either spontaneously or in
   response to a request.  A Provider can be a Posture Evaluator,
   Posture Collector, Data Store (see Section 3.1.3), or an application
   that has aggregated Posture Assessment Information that can be

   The Provider implements the capabilities and functions that must be
   handled to share or provide Posture Assessment information.

   One means by which a Provider shares information, is in response to a
   direct request from a Consumer.

   A Provider may also share information spontaneously.  Use cases such
   as the change in a posture state require that a Provider be able to
   provide such changes or updates especially to Consumers such as
   Security Information and Event Management (SIEM) systems; similarly,
   SIEM applications that are providing live information require any
   such updates or changes to posture information to be provided
   spontaneously.  Authorization for the enabling for these unsolicited
   messages happens through the Controller at the time that both
   Provider and Consumers request authorization for (spontaneous)

   The information provided, may be filtered or truncated to provide a
   subset of the requested information to honor the request.  This
   truncation may be performed based on the Consumer's request and/or
   the Provider's ability to filter.  The latter case may be due to
   security considerations (e.g. authorization restrictions due to
   domain segregation, privacy, etc.).

   The Provider may only be able to share the Posture Assessment
   Information using a specific data model and protocol.  It may use a
   standard data model and/or protocol, a non-standard data model and/or
   protocol, or any combination of standard and non-standard data models
   and protocols.  However, it must support either one or more standard
   data models, or one or more standard protocols.  It may also choose
   to advertise its capabilities through a metadata abstraction within
   the data model itself, or through the use of the registration
   function of the Controller (see Section 3.1.4).

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   The Provider must be authorized to provide the Posture Assessment
   Information for specific consumers.

3.1.2.  Consumer

   The Consumer (Cs) is the component that requests or accepts Posture
   Assessment Information and/or Guidance.  A Consumer can be a Posture
   Evaluator, Report Generator, Data Store (see Section 5.2), or an
   application that consumes Posture Assessment Information in order to
   perform another function.

   As described in Section 2.2 of the SACM Use Cases
   [I-D.ietf-sacm-use-cases], several usage scenarios are posed with
   different application types requesting posture assessment
   information.  Whether it is a configuration verification system; a
   checklist verification system; or a system for detecting posture
   deviations, compliance or vulnerabilities, they all need to acquire
   information about Posture Assessment.  The architectural component
   performing such requests is a Consumer.

   The Consumer implements the capabilities and functions that must be
   handled in order to enable a Posture Assessment Information Request.
   Requests can be either for a single posture attribute or a set of
   posture attributes; those attributes can be the raw information, or
   an evaluation result based upon that information.  The Consumer may
   further choose to query for the information directly (one-time
   query), or to request for updates to be provided as the Posture
   Assessment Information changes (subscription).  A request could be
   made directly to an explicitly identified Provider, but a Consumer
   may also desire to obtain the information without having to know the
   available Providers.

   There may be instances where a Consumer may be requesting information
   from various Providers and, due to its policy or application
   requirements, may need to be better informed of the Providers and
   their capabilities.  In those use cases, a Consumer may also request
   to discover the respective capabilities of those Providers using the
   discovery function of the Controller (see Section 3.1.4) or may
   request metadata reflecting the capabilities of the Providers.

   The Controller (described below) must authorize a Consumer to acquire
   the information it is requesting.  The Consumer may also be subject
   to limits or constraints on the numbers, types, sizes, and rate of

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3.1.3.  Types of Providers and Consumers

   SACM Providers and Consumers can perform a variety of SACM-related
   tasks.  For example, a Collector can perform Collection tasks; an
   Evaluator can perform Evaluation tasks.  A single Provider or
   Consumer may be able to perform only one task, or multiple tasks.
   SACM defines the following types of Providers/Consumers:  Collector

   A collector consumes Guidance and/or other Posture Assessment
   Information; it provides Posture Assessment Information.  Collectors
   may be internal or external.  As a SACM component, a Collector may be
   a Consumer as it may consume guidance information and may also be a
   Provider as it may publish the collected information.  Internal Collector

   An internal collector is a collector that runs on the endpoint and
   collects posture information locally.  External Collector

   An external collector is a collector that observes endpoints from
   outside.  These collectors may be configured and operated to manage
   assets for reasons including, but not limited to, posture assessment.
   Collectors that are not primarily intended to support posture
   assessment (e.g. intrusion detection systems) may still provide
   information that speaks to endpoint posture (e.g. behavioral


   o  A RADIUS server, which collects information about which endpoints
      have logged onto the network

   o  A network profiling system, which collects information by
      discovering and classifying network nodes

   o  A Network Intrusion Detection System (NIDS) sensor, which collects
      information about endpoint behavior by observing network traffic

   o  A vulnerability scanner, which collects information about endpoint
      configuration by scanning endpoints

   o  A hypervisor, which collects information about endpoints running
      as virtual guests in its host environment

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   o  A management system that configures and installs software on the
      endpoint, which collects information based on its provisioning
      activities  Collector Interactions With Target Endpoints

   TODO - examples of endpoint interactions with local internal
   collector (e.g.  NEA client), endpoint with remote internal collector
   (SNMP query), and external collector (sensor)  Evaluator

   An evaluator consumes Posture Assessment Information, Evaluation
   Results, and/or Guidance; it provides Evaluation Results.  An
   evaluator may consume endpoint attribute assertions, previous
   evaluations of posture attributes, or previous reports of Evaluation

   TODO: update the terminology doc to reflect this definition

   Example: a NEA posture validator [RFC5209]  Report Generator

   A report generator consumes Posture Assessment Information,
   Evaluation Results, and/or Guidance; it provides reports.  These
   reports are based on:

   o  Endpoint Attribute Assertions, including Evaluation Results

   o  Other Reports (e.g., a weekly report may be created from daily

   It may summarize data continually, as the data arrives.  It also may
   summarize data in response to an ad hoc query.  Data Store

   A data store consumes any data; it provides any data.

3.1.4.  Controller

   The Controller (Cr or Controller) is a component defined to
   facilitate the overall SACM management and control system functions.
   This component is responsible for handling the secure communications
   establishment (such as the authentication and authorization) between
   Providers and Consumers.  In addition, the Controller may also handle
   how the data may be routed.  While the architecture defines the

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   Controller as a single component, implementations may implement this
   to suit the different deployment and scaling requirements.  In
   particular, for the data handling, SACM defines three types of

   Broker:  Intermediary negotiating connection between Provider and
    Consumer.  Implements only control plane functions.  A Controller
    acting as a Broker:

    *  Receives a request for information from a Consumer and instructs
       the Consumer where and how retrieve the requested information.

    *  Receives a publication request from a Provider and instructs the
       Provider where and how to deliver the published information.

    *  The information itself is neither distributed nor stored by the

   Proxy:  Intermediary negotiating on behalf of a Consumer or Provider.
    Implements both control and data plane functions.  A Controller
    acting as a Proxy:

    *  Receives a request for information from a Consumer, retrieves the
       information from the appropriate Providers, and provides the
       information to the Consumer.

    *  Receives a publication request from a Provider, accepts the
       published information, and distributes it to appropriate

    *  The information itself is distributed by, but not stored by, the

   Repository:  Intermediary receiving and storing data from a Provider,
    and providing stored data to a Consumer.  Implements both control
    and data plane functions.  A Controller acting as a Repository:

    *  Receives a request for information from a Consumer, retrieves the
       information from its data stores, and provides the information to
       the Consumer.

    *  Receives a publication request from a provider, stores the
       published information, and distributes it to appropriate

    *  The information itself is both handled by and stored by the

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   A single instantiation of a Controller may be a Broker, Proxy, or
   Repository, or any combination thereof.

   Through the use of a discovery mechanism, Consumers can have
   visibility into the Providers present, the type(s) of Posture
   Assessment Information available, and how it can be requested.
   Similarly, a Provider may need to publish what Posture Assessment
   Information it can share and how it can share it (e.g. protocol,
   filtering capabilities, etc.).  Enabling this visibility through a
   Controller or through metadata publication also allows for the
   distinct definition of security considerations (e.g. authorized
   registration / publication of capabilities by Providers) beyond how a
   Provider may define its own capability.

   Beyond the control and management functions for the SACM system, a
   Controller may also provide proxy or broker or repository (and
   possibly routing) services in the data plane.  In the deployment
   scenario where Providers do not assert the need to know their
   Consumers and/or vice versa, the Controller can thus provide the
   appropriate services to ensure the Posture Assessment Information is
   appropriately communicated from the Providers to the authorized

   The Controller, acting as a management control plane, helps define
   how to manage an overall SACM system that allows for Consumers to
   obtain the desired Posture Assessment Information without the need to
   distinctly know and establish one (Consumer) to many (Provider)
   connections.  Similarly, a Provider may not need to distinctly know
   and establish one (Provider) to many (Consumer) connections; e.g. the
   Controller enables the means to allow a SACM system to support many
   to many connections.  Note that the Controller also allows for the
   direct discovery and connection between a Consumer and Provider.

   As a SACM component, the Controller may be instantiated within a
   system or device acting as a Provider or a Consumer (or both), or as
   its own distinct Controller entity.  In a rich SACM environment, it
   is feasible to instantiate a Controller that provides both the
   management (and control) functions for SACM as well as providing the
   data plane services for the actual data, e.g.  Posture Assessment
   Information flow.  Note that Controllers may be implemented to only
   provide control plane functions (broker), or both control plane
   functions and data plane services (proxy or repository).

4.  Interfaces between Consumers, Providers, and Controllers

   A SACM interface is a transport carrying operations (e.g. publication
   via a RESTful API).  As shown in Figure 1, communication can proceed
   with the following interfaces and expected functions and behaviors:

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   A:  interface "A" shown in Figure 1 handles the management and
    control functions that are needed to establish, at minimum, a secure
    communication between Consumers and Providers.  The interface must
    also handle the functions to allow for the discovery and
    registration of the Providers as well as the ways in which Posture
    Assessment Information can be provided (or requested).

   B:  interface "B" shown in Figure 1 enables Providers to share their
    Posture Assessment Information spontaneously; similarly, it enables
    Consumers to request information without having to know the
    identities (or reachability) of all the Providers that can fulfill
    Consumers' requests.

   C:  interface "C" shown in Figure 1 illustrates the ability and
    desire for Consumers and Providers to be able to communicate
    directly when a Provider is sharing Posture Assessment Information
    directly to a Consumer.  The interface allows for the different data
    models and protocols to be used between a Consumer and a Provider
    with the expectation that the appropriate authentication and
    authorization mechanisms have been employed to establish a secure
    communication link between the Consumer and the Provider.
    Typically, it is expected that the secure link establishment occurs
    as a management or control function through the abstracted
    Controller role (e.g. the Controller could be a broker or could be
    embedded in a Consumer or a Provider).

   A variety of protocols, such as SNMP, NETCONF, NEA protocols
   [RFC5209], and other similar interfaces, may be used for collection
   of data from the target endpoints by the Posture Information
   Provider.  Those interfaces are outside the scope of SACM.

5.  Component Functions

   SACM components are composed of a variety of functions, which may be
   instantiated on a single endpoint or on separate standalone endpoints
   providing various roles.  An endpoint MUST implement one or more of
   these functions to be considered a SACM component.  A SACM solution
   offers a set of functions across a set of SACM components.

   The functions described here are the minimum set that is mandatory to
   implement in a SACM solution.  A SACM solution MAY implement
   additional functions.

5.1.  Control Plane Functions

   Control plane functions represent various services offered by the
   Controller to the Providers and Consumers to facilitate sharing of

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   information.  Control plane functions include, but are not limited

   Authentication:  The authentication of Consumers and Providers
    independent of the actual information-sharing communication channel.
    While authentication between peers (e.g. a Consumer and a Provider)
    can be achieved directly through peer to peer authentication (using
    TLS for instance), there are use cases where:

    *  Consumers may request information independent of knowing the
       identities of the Providers.

    *  Providers may want to share the information without prior

   To address the above use cases, the architecture must account for an
   abstraction where a Controller may be defined to effect the
   authentication of the Consumers and Providers independent of the
   actual information-sharing communication channel.  Consumers and
   Providers that consume or publish information without requiring
   knowledge of the Providers and Consumers respectively would function
   in a SACM system where the Controller is a distinct entity.  As a
   distinct SACM component, the Controller would authenticate Providers
   and Consumers.

   Authorization:  The restriction of Posture Assessment Information
    sharing between the Consumers and Providers.  At minimum, a
    management function must define the necessary policies to control
    what Providers can publish and Consumers to accept.  The Controller
    is the authority for the type of Posture Information that a Provider
    can publish and a Consumer can accept.  If a Controller is a Broker,
    then it may only grant authorization to the capabilities requested
    by the Provider or Consumer.  When acting as a Proxy, as part of its
    authorization, the Controller may further obscure or block
    information being shared by a Provider as it distributes it to a
    Consumer.  Similarly, a Repository may block information as recieved
    by the Provider and pass to the Consumer and to its storage the
    resulting authorized information.  A Provider may also enforce its
    own authorization based upon its connection to a Controller; though,
    in the case where an application includes both the Provider and
    Controller roles, it can choose to implement all authorization on
    the Controller.  Similarly, a Consumer may enforce its own
    authorization of what data it can receive based on the Controller
    (or Provider) it is communicaticating with; in the case where an
    application includes both the Consumer and Controller roles, it can
    choose to implement all the authorization on the Controller.

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    Identity Management:  Since Identity Management for authentication
     and authorization policies is best performed via a centralized
     component, the Controller also facilitates this function.

     The Controller needs to be able to identify the endpoints
     participating as SACM components and the roles that they play.
     Similar to how access control may be effected via Authentication,
     Authorization, and Accounting Systems (e.g.  AAA services), the
     same principle is defined; as AAA services depend on Identity
     Management services, the Controller will need a similar function
     and interface to Identity Management services.  Note that
     implementations of this function is abstractly centralized, but to
     address scalability and the need to manage different resources
     (e.g. users, processes and devices) a distributed system that is
     centrally coordinated may be used.

   Registration/Discovery:  A SACM ecosystem needs to provide the
    ability for devices to discover Providers, Consumers, Controllers
    and their respective capabilities.  For a Consumer to be able to
    obtain the information of interest must either configure itself to
    know what Providers to communicate with directly (and their known
    capabilities, such as the supported data model and information
    provided) or can dynamically discover the information that is
    available.  Similarly, Providers may need to either be configured to
    know who to publish the information to, or can dynamically discover
    its Consumers.

    In the case where there is a Controller, the capabilities of the
    Controller must also be advertised so that Providers and Consumers
    may know how the data is being handled as well (e.g. if acting as a
    Broker or Repository).  The Controller also provides the function of
    registering the Providers and Consumers; the registration function
    enables the Controller to also affect the authorization afforded to
    the Provider or Consumer.

5.2.  Data Plane Functions

   There are three basic functions to facilitate data flow:

   Subscription:  A Consumer that wants to recieve information from a
    specific Provider or from the Controller advertising the
    availability of specific information (that may come from more than
    one Provider) will effectively subscribe to recieve the information
    spontaneously and continuously as new information as subscribed to
    becomes available.

   Publication  A Provider being registered through the Controller to
    provide specific information, may publish the information either

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    directly to the Consumers or to the Controller that is acting as the
    broker or respository.

   Query/Response  A Consumer may contact the Provider directly and
    request the information through a query operation; and in response,
    the Provider would send the information directly to the Consumer.

6.  Component Capabilities

   TODO: add a discussion of "capability" as being able to talk a
   specific data model, data operations, or SACM transport

   TODO: data plane capabilities / control plane capabilities can be
   discovered via querying the controller

7.  Example Illustration of Functions and Workflow

   TODO: once the group reaches consensus on content for the previous
   sections, revise all this text based upon the agreed-upon

                     | +-------------------------------+
                     | |                               |
                     +-|        Controller (Cr)        |
                          //   /            \   \\
                         //   /              \   \\
                      A //   /                \   \\ A
                       //   /                  \   \\
                      //   /  B             B   \   \\
                     //   /                      \   \\
    +------------------------+           +------------------------+
    | +----------------------+     A     | +------------------------+
    | |                      |===========| |                        |
    | |    Consumer (C)      |-----------| |      Provider (P)      |
    +-|                      |     C     +-|                        |
       +---------------------+             +------------------------+

                      Figure 2: Communications Model

   SACM's focus is on the automation of collection, verification and
   update of system security configurations pertaining to endpoint
   assessment.  In order to carry out these tasks, the architectural
   components shown in Figure 1 can be further refined as:

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   Providers:  a Provider may be dedicated to perform either the
    collection, aggregation or evaluation of one or more posture
    attributes whose results can be conveyed to a Consumer.  In this
    example form of the SACM architecture model, these are shown as
    Collection, Evaluation, and Results Providers.  Note that there may
    be posture attributes or posture assessment information that
    articulates Guidance information which may or may not be present in
    the architecture.

   Consumers:  a Consumer may request or receive one or more posture
    attributes or posture assessment information from a Provider for
    their own use.  In this example form of the SACM architecture model,
    these are shown as Collection, Evaluation, and Results Consumers.
    Note that there may be posture attributes or posture assessment
    information articulating Guidance information which may or may not
    be present in the architecture to be provided or consumed.

   Data Stores:  a Data Store is both a Provider and a Consumer, storing
    one or more posture attributes or assessments for endpoints.  It
    should be understood that these repositories interface directly to a
    Provider or Consumer (and Guidance) but the interfaces used to
    interact between them is outside the scope of SACM (e.g. no
    interface arrows are shown in the architecture).

   Figure 3 illustrates an example flow for how Posture Assessment
   Information may flow.

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                                    |Evaluation   |
                   +-------------+  |Guidance     +--+
                   |Endpoint     |  |Function     |  |
           +-------+             |  +-------------+  |
           |       |             |                   |
           |       +-------+-----+             +-----v-------+
           | Collection    |                   |Evaluation   |
         +-> Function   +--+--------+          |Function     |
         | |            |Collection |    +-----------+   +----------+
         | +------------+Provider   |    |           |---|          |
         |              |           |    |Collection |   |Evaluation|
         |              |           |    |Consumer   |   |Provider  |
         |              +----+------+    +----^------+   +---+------+
        ++---------+         |                |              |
        |Collection|   +-----v------+     +---+--------+     |
        |Guidance  |   |            |     |Collection  |     |
        |Function  |   |Collection  |     |Provider    |     |
        |          |   |Consumer    |-----|            |     |
        +----------+   +------------+     +------------+     |
                                  | Collection |             |
                                  | Data Store |             |
                                  +------------+             |
            +--------------+           +---------------+     |
            |Evaluation    |           |Evaluation     |     |
            |Results       |           |Consumer       <-----+
            |Provider      |-----------|               |
            +-----+--------+           +---------------+
                  |     |Results Reporting|
                  |     |Function         |
                  |     +------------^----+
                  |                  |
            +-----v--------+    +----+------+
            |Evaluation    |    |Reporting  |
            |Results       |    |Guidance   |
            |Consumer      |    |Data Store |
            +---+----------+    +-----------+ +-------------+
                |                             | Results     |
                +-----------------------------> Data Store  |
                                              |             |

                Figure 3: Example Posture Information Flow

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   TODO - add example of / more content around interactions with
   endpoint, possible communications patterns

8.  Acknowledgements

   The authors would like to thank Jim Bieda, Henk Birkholz, Jessica
   Fitzgerald-McKay, Trevor Freeman, Adam Montville, and David
   Waltermire for participating in architecture design discussions,
   reviewing, and contributing to this draft.

9.  IANA Considerations

   This memo includes no request to IANA.

10.  Security Considerations

   The SACM architecture defines three main components that interface
   with each other both for management and control (in the control
   plane) and for the sharing of Posture Assessment Information.
   Considerations for transitivity of trust between a Provider and
   Consumer can be made if there is a well understood trust between the
   Provider and the Controller and between the Consumer and Controller.
   The trust must include strong mutual authentication, at minimum,
   between the Provider and Controller and between the Consumer and

   To address potential Man-in-the-Middle (MitM) attacks, it is also
   strongly recommended that the communications be secured to include
   replay protection and message integrity (e.g. transport integrity and
   if required, data integrity).  Similarly, to avoid potential message
   disclosure (e.g. where privacy may be needed), confidentiality should
   also be provided.

   As the Controller provides the security functions for the SACM
   system, the Controller should provide strong authorizations based on
   either or both business and regulatory policies to ensure that only
   authorized Consumers and obtaining Posture Assessment Information
   from authorized Providers.  It is presumed that once authenticated
   and authorized, the Provider, Controller or Consumer is deemed
   trustworthy; though note that it is possible that the modules or
   devices hosting the SACM components may be compromised as well (e.g.
   due to malware or tampering); however, addressing that level of
   trustworthiness is out of scope for SACM.

   As the data models defined through the interfaces are transport
   agnostic, the Posture Assessment Information data in the interfaces
   may leverage the transport security properties as the interfaces are
   transported between the Provider, Consumer and Controller.  However,

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   there may be other devices, modules or components in the path between
   the Provider, Consumer and Controller that may observe the interfaces
   flowing through them.

11.  References

11.1.  Normative References

              Cam-Winget, N. and L. Lorenzin, "Secure Automation and
              Continuous Monitoring (SACM) Requirements", draft-ietf-
              sacm-requirements-08 (work in progress), July 2015.

              Birkholz, H., "Secure Automation and Continuous Monitoring
              (SACM) Terminology", draft-ietf-sacm-terminology-07 (work
              in progress), July 2015.

              Waltermire, D. and D. Harrington, "Endpoint Security
              Posture Assessment - Enterprise Use Cases", draft-ietf-
              sacm-use-cases-10 (work in progress), July 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

11.2.  Informative References

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444,
              DOI 10.17487/RFC3444, January 2003,

   [RFC5209]  Sangster, P., Khosravi, H., Mani, M., Narayan, K., and J.
              Tardo, "Network Endpoint Assessment (NEA): Overview and
              Requirements", RFC 5209, DOI 10.17487/RFC5209, June 2008,

Authors' Addresses

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   Nancy Cam-Winget (editor)
   Cisco Systems
   3550 Cisco Way
   San Jose, CA  95134

   Email: ncamwing@cisco.com

   Lisa Lorenzin
   Pulse Secure
   2700 Zanker Rd, Suite 200
   San Jose, CA  95134

   Email: llorenzin@pulsesecure.net

   Ira E McDonald
   High North Inc
   PO Box 221
   Grand Marais, MI  49839

   Email: blueroofmusic@gmail.com

   Aaron Woland
   Cisco Systems
   1900 South Blvd. Suite 200
   Charlotte, NC  28203

   Email: loxx@cisco.com

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