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Versions: (draft-mandm-sacm-architecture) 00 01 02 03 04

SACM Working Group                                          A. Montville
Internet-Draft                                                 B. Munyan
Intended status: Standards Track                                     CIS
Expires: August 26, 2019                               February 22, 2019


   Security Automation and Continuous Monitoring (SACM) Architecture
                        draft-ietf-sacm-arch-01

Abstract

   This memo defines a Security Automation and Continuous Monitoring
   (SACM) architecture.  This work is built upon
   [I-D.ietf-mile-xmpp-grid], 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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://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 August 26, 2019.

Copyright Notice

   Copyright (c) 2019 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
   (https://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.  Open Questions  . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements notation . . . . . . . . . . . . . . . . . .   3
   2.  Terms and Definitions . . . . . . . . . . . . . . . . . . . .   4
   3.  Architectural Overview  . . . . . . . . . . . . . . . . . . .   4
     3.1.  SACM Roles  . . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Exploring An XMPP-based Solution  . . . . . . . . . . . .   5
     3.3.  Example Architecture using XMPP-Grid and Endpoint Posture
           Collection Protocol . . . . . . . . . . . . . . . . . . .   8
   4.  Components, Capabilities, Interfaces, and Workflows . . . . .  10
     4.1.  Components  . . . . . . . . . . . . . . . . . . . . . . .  10
     4.2.  Capabilities  . . . . . . . . . . . . . . . . . . . . . .  11
     4.3.  Interfaces  . . . . . . . . . . . . . . . . . . . . . . .  11
     4.4.  Workflows . . . . . . . . . . . . . . . . . . . . . . . .  12
       4.4.1.  IT Asset Management . . . . . . . . . . . . . . . . .  12
       4.4.2.  Vulnerability Management  . . . . . . . . . . . . . .  12
       4.4.3.  Configuration Management  . . . . . . . . . . . . . .  14
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  15
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  16
   Appendix A.  Mapping to RFC8248 . . . . . . . . . . . . . . . . .  18
   Appendix B.  Example Components . . . . . . . . . . . . . . . . .  21
     B.1.  Policy Services . . . . . . . . . . . . . . . . . . . . .  21
     B.2.  Software Inventory  . . . . . . . . . . . . . . . . . . .  22
     B.3.  Datastream Collection . . . . . . . . . . . . . . . . . .  23
     B.4.  Network Configuration Collection  . . . . . . . . . . . .  23
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24

1.  Introduction

   The purpose of this draft is to define an architectural solution for
   a SACM Domain.  This draft also defines an implementation of the
   architecutre, built upon [I-D.ietf-mile-xmpp-grid] and
   [I-D.ietf-sacm-ecp].  These approaches complement each other to more
   completely meet the spirit of [RFC7632] and requirements found in
   [RFC8248].



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   This solution gains the most advantage by supporting a variety of
   collection mechanisms.  In this sense, the solution ideally intends
   to enable a cooperative ecosystem of tools from disparate sources
   with minimal operator configuration.  The solution described in this
   document seeks to accommodate these recognitions by first defining a
   generic abstract architecture, then making that solution somewhat
   more concrete.

   Keep in mind that, at this point, the draft is tracking ongoing work
   being performed primarily 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 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.

1.1.  Open Questions

   [NOTE: This section will eventually be removed.]

   The following is a list of open questions we still have about the
   path forward with this exploration:

   o  Should workflows be documented in this draft or separate drafts?

   o  Should interfaces be documented in workflow drafts or separate
      drafts (or even this draft)?

1.2.  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].






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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 state collection mechanisms, and makes
   every attempt to respect [RFC7632] and [RFC8248].  At the foundation
   of any architecture are entities, or components, that need to
   communicate.  They communicate by sharing information, where, in a
   given flow one or more components are consumers of information and
   one or more components are providers of information.

                  +--------------------+
                  | Feeds/Repositories |
                  |  of External Data  |
                  +--------------------+
                             |
                             |
*****************************v**************** Enterprise Boundary ************
*                            |                                                *
*  +--------------+          |     +--------------+                           *
*  | Orchestrator |          |     | Repositories |                           *
*  +------^-------+          |     +----^---------+                           *
*         |                  |          |              +----------------+     *
*      A  |                B |        C |              | Downstream Uses|     *
*         |                  |          |              | +-----------+  |     *
*  +------v------------------v----------v------+       | |Evaluations|  |     *
*  |           Message Transfer System         <-------> +-----------+  |     *
*  +----------------------^--------------------+     D | +-----------+  |     *
*                       E |                            | | Analytics |  |     *
*                         |                            | +-----------+  |     *
*           +-------------v---------+                  | +-----------+  |     *
*           | Collection Subsystems |                  | | Reporting |  |     *
*           +-----------------------+                  | +-----------+  |     *
*                                                      +----------------+     *
*******************************************************************************


                      Figure 1: Notional Architecture

   As shown in Figure 1, the notional SACM architecture consists of some
   basic SACM Components using a message transfer system to communicate.
   While not depicted, the message transfer system is expected to
   maximally align with the requirements described in [RFC8248], which




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   means that the message transfer system will support brokered (i.e.
   point-to-point) and proxied data exchange.

   Additionally, component-specific interfaces (i.e. such as A, B, C, D,
   and E in Figure 1) are expected to be specified logically then bound
   to one or more specific implementations.  This SHOULD be done for
   each capability related to the given SACM Component.

3.1.  SACM Roles

   This document suggests a variety of players in a cooperative
   ecosystem - we call these players SACM Components.  SACM Components
   may be composed of other SACM Components, and each SACM Component
   plays one, or more, of several roles relevant to the ecosystem.
   Generally each role is either a consumer of information or a provider
   of information.  The "Components, Capabilities, Interfaces, and
   Workflows" section provides more details about SACM Components that
   play these types of roles.

3.2.  Exploring An XMPP-based Solution

   Figure 2 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 2, this
   architecture does allow point-to-point interfaces.  In fact,
   [I-D.ietf-mile-xmpp-grid] provides brokering capabilities to
   facilitate such point-to-point data transfers).  Additionally, each
   of the SACM Components depicted in Figure 2 may be a provider, a
   consumer, or both, depending on the workflow in context.

















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

                     Figure 2: XMPP-based Architecture

   [I-D.ietf-mile-xmpp-grid] 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, [I-D.ietf-mile-xmpp-grid] 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 2 we therefore use "XMPP-Grid+" to indicate something more
   than [I-D.ietf-mile-xmpp-grid] 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)
   [I-D.ietf-mile-xmpp-grid] 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



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      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.





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   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.

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

   Figure 3 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.
























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

             Figure 3: XMPP-based Architecture including EPCP







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4.  Components, Capabilities, Interfaces, and Workflows

   The SACM Architecture consists of a variety of SACM Components, and
   named components are intended to embody one or more specific
   capabilities.  Interacting with these capabilities will require at
   least two levels of interface specification.  The first is a logical
   interface specification, and the second is at least one binding to a
   specific transfer mechanism.  An example transfer mechanism is XMPP-
   Grid+.

   The following subsections describe some of the components,
   capabilities, and interfaces we may expect to see participating in a
   SACM Domain.

4.1.  Components

   The following is a list of suggested SACM Component classes and
   specializations.

   o  Repository

      *  Vulnerability Information Repository

      *  Asset Inventory Repository

         +  Software Inventory Repository

         +  Device Inventory Repository

      *  Configuration Policy Repository

      *  Configuration State Repository

   o  Collector

      *  Vulnerability State Collector

      *  Asset Inventory Collector

         +  Software Inventory Collector

         +  Device Inventory Collector

      *  Configuration State Collector

   o  Evaluator

      *  Vulnerability State Evaluator



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      *  Asset Inventory Evaluator

         +  Software Inventory Evaluator

         +  Device Inventory Evaluator

      *  Configuration State Evaluator

   o  Orchestrator

      *  Vulnerability Management Orchestrator

      *  Asset Management Orchestrator

         +  Software Inventory Evaluator

         +  Device Inventory Evaluator

      *  Configuration Management Orchestrator

4.2.  Capabilities

   Repositories will have a need for fairly standard CRUD operations and
   query by attribute operations.  Collector interfaces may enable ad
   hoc assessment (on-demand processing), state item watch actions (i.e.
   watch a particular item for particular change), persisting other
   behaviors (i.e. setting some mandatory reporting period).  Evaluators
   may have their own set of interfaces, and an Assessor would represent
   both Collector and Evaluation interfaces, and may have additional
   concerns added to an Assessor Interface.

   Not to be overlooked, whatever solution at which we arrive, per
   [RFC8248], MUST support capability negotiation.  While not explicitly
   treated here, each interface will understand specific serializations,
   and other component needs to express those serializations to other
   components.

   A capability language is fully explored in mandl-sacm-tool-
   capability-language (to be submitted).

4.3.  Interfaces

   Interfaces should be derived directly from identified workflows,
   several of which are described in this document.







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4.4.  Workflows

   The workflows described in this document should be considered as
   candidate workflows - informational for the purpose of discovering
   the necessary components and specifying their interfaces.

4.4.1.  IT Asset Management

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

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

   An IT asset management capability needs to be able to:

   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

4.4.2.  Vulnerability Management

   Vulnerability management is a relatively established process.
   According to the [CISCONTROLS], continuous vulnerability management
   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.







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4.4.2.1.  Vulnerability Assessment Workflow Assumptions

   A number of assumptions must be stated to clarify the scope of a
   vulnerability assessment workflow:

   o  The enterprise has received vulnerability description information,
      and that the information has already been processed into
      vulnerability detection data that the enterprise's security
      software tools can understand and use.

   o  The enterprise has a suitable IT Asset Management capability

   o  The enterprise has a means of extracting relevant information
      about enterprise endpoints in a form that is compatible with the
      vulnerability description data (appropriate Collectors for their
      technologies)

   o  All information described in this scenario is available in the
      vulnerability description data and serves as the basis of
      assessments.

   o  The enterprise can provide all relevant information about any
      endpoint needed to perform the described assessment (the
      appropriate Repositories are available)

   o  The enterprise has a mechanism for long-term storage of
      vulnerability description information, vulnerability detection
      data, and vulnerability assessment results.

   o  The enterprise has a procedure for reassessment of endpoints at
      some point after initial assessment

4.4.2.2.  Vulnerability Assessment Workflow

   When new vulnerability description information is received by the
   enterprise, affected endpoints are identified and assessed.  The
   vulnerability is said to apply to an endpoint if the endpoint
   satisfies the conditions expressed in the vulnerability detection
   data.

   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.





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   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 many 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 collect it from the target
   endpoint.  Of course, some implementations of endpoint management
   capabilities may prefer to enable operators to perform this
   collection under certain circumstances, even when sufficient
   information can be provided by the endpoint management capabilities
   (e.g. there may be freshness requirements for information).

   The collection of additional endpoint information for the purpose of
   vulnerability assessment does not necessarily need to be a pull by
   the vulnerability assessment capabilities.  Over time, some new
   pieces of information that are needed during common types of
   assessments might be identified.  Endpoint management capabilities
   can be reconfigured to have this information delivered automatically.
   This avoids the need to trigger additional Collection Tasks to gather
   this information during assessments, streamlining the assessment
   process.  Likewise, it might be observed that certain information
   delivered by endpoint management capabilities is rarely used.  In
   this case, it might be useful to re-configure the endpoint management
   capabilities to no longer collect this information to reduce network
   and processing overhead.  Instead, a new Collection Task can be
   triggered to gather this data on the rare occasions when it is
   needed.

4.4.3.  Configuration Management

   Configuration management involves configuration assessment, which
   requires state assessment (TODO: Tie to SACM use cases).  The
   [CISCONTROLS] specify two high-level controls concerning



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   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 a requirement to:
   "Establish, implement, and actively manage (track, report on,
   correct) the security configuration of (endpoints) 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.

5.  Privacy Considerations

   TODO

6.  Security Considerations

   TODO






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7.  IANA Considerations

   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

8.  References

8.1.  Normative References

   [I-D.ietf-mile-xmpp-grid]
              Cam-Winget, N., Appala, S., Pope, S., and P. Saint-Andre,
              "Using XMPP for Security Information Exchange", draft-
              ietf-mile-xmpp-grid-09 (work in progress), December 2018.

   [I-D.ietf-sacm-ecp]
              Haynes, D., Fitzgerald-McKay, J., and L. Lorenzin,
              "Endpoint Posture Collection Profile", draft-ietf-sacm-
              ecp-04 (work in progress), February 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>.

8.2.  Informative References

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







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   [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>.

   [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>.

   [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>.







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   [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

   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.

   +----------+----------------------------------------+---------------+



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   | 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            |               |



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   |          |                                        |               |
   | 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                   |               |



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   |          |                                        |               |
   | 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

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).





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   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 4: EPCP Collection Architecture

   In Figure 4, 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
   [I-D.ietf-mile-xmpp-grid] 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.



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   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], [I-D.ietf-mile-xmpp-grid], 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.





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Authors' Addresses

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

   Email: adam.w.montville@gmail.com


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

   Email: bill.munyan.ietf@gmail.com

































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