Internet DRAFT - draft-salowey-sacm-xmpp-grid
draft-salowey-sacm-xmpp-grid
SACM J. Salowey
Internet-Draft Tableau Software
Intended status: Standards Track L. Lorenzin
Expires: October 31, 2015 C. Kahn
Pulse Secure
S. Pope
S. Appala
A. Woland
N. Cam-Winget, Ed.
Cisco Systems
April 29, 2015
XMPP Protocol Extensions for Use in SACM Information Transport
draft-salowey-sacm-xmpp-grid-02
Abstract
This document defines a transport protocol for use with the Security
Automation and Continuous Monitoring (SACM) Architecture.
Status of This Memo
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This Internet-Draft will expire on October 31, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Glossary of Terms . . . . . . . . . . . . . . . . . . . . 3
1.2. What is XMPP-Grid? . . . . . . . . . . . . . . . . . . . 6
1.3. Overview of XMPP-Grid . . . . . . . . . . . . . . . . . . 6
1.4. Benefits of XMPP-Grid . . . . . . . . . . . . . . . . . . 9
1.5. Example Workflow . . . . . . . . . . . . . . . . . . . . 10
2. Applicability of XMPP-Grid to SACM Use Cases . . . . . . . . 12
2.1. Applicability of XMPP-Grid to SACM Usage Scenarios . . . 12
2.1.1. SACM Definition and Publication of Automatable
Configuration Checklists . . . . . . . . . . . . . . 12
2.1.2. SACM Automated Checklist Verification . . . . . . . . 13
2.1.3. SACM Detection of Posture Deviations . . . . . . . . 13
2.1.4. SACM Endpoint Information Analysis and Reporting . . 14
2.1.5. SACM Asynchronous Compliance/Vulnerability Assessment
at Ice Station Zebra . . . . . . . . . . . . . . . . 14
2.1.6. SACM Identification and Retrieval of Guidance . . . . 14
2.1.7. SACM Guidance Change Detection . . . . . . . . . . . 15
3. XMPP-Grid Architecture . . . . . . . . . . . . . . . . . . . 15
3.1. XMPP Overview . . . . . . . . . . . . . . . . . . . . . . 16
3.2. XMPP-Grid Protocol Extensions to XMPP . . . . . . . . . . 17
3.3. XMPP-Grid Controller Protocol Flow . . . . . . . . . . . 18
3.4. XMPP-Grid Node Connection Protocol Flow . . . . . . . . . 20
3.4.1. Authentication . . . . . . . . . . . . . . . . . . . 20
3.4.2. Registration . . . . . . . . . . . . . . . . . . . . 20
3.4.3. Authorization . . . . . . . . . . . . . . . . . . . . 23
3.5. XMPP-Grid Topics Protocol Flow . . . . . . . . . . . . . 26
3.5.1. Topic Versioning . . . . . . . . . . . . . . . . . . 27
3.5.2. Topic Discovery . . . . . . . . . . . . . . . . . . . 27
3.5.3. Subtopics and Message Filters . . . . . . . . . . . . 27
3.6. XMPP-Grid Protocol Details . . . . . . . . . . . . . . . 30
4. XMPP-Grid Compatibility with IF-MAP Information Model . . . . 36
4.1. MAP Server as XMPP-Grid Subscriber for Metadata
Aggregation . . . . . . . . . . . . . . . . . . . . . . . 38
4.2. MAP Server as XMPP-Grid Publisher for Metadata
Dissemination . . . . . . . . . . . . . . . . . . . . . . 40
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40
6. Security Considerations . . . . . . . . . . . . . . . . . . . 40
6.1. Trust Model . . . . . . . . . . . . . . . . . . . . . . . 41
6.1.1. Network . . . . . . . . . . . . . . . . . . . . . . . 41
6.1.2. XMPP-Grid Nodes . . . . . . . . . . . . . . . . . . . 41
6.1.3. XMPP-Grid Controller . . . . . . . . . . . . . . . . 41
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6.1.4. Certification Authority . . . . . . . . . . . . . . . 42
6.2. Threat Model . . . . . . . . . . . . . . . . . . . . . . 42
6.2.1. Network Attacks . . . . . . . . . . . . . . . . . . . 42
6.2.2. XMPP-Grid Nodes . . . . . . . . . . . . . . . . . . . 43
6.2.3. XMPP-Grid Controllers . . . . . . . . . . . . . . . . 44
6.2.4. Certification Authority . . . . . . . . . . . . . . . 45
6.3. Countermeasures . . . . . . . . . . . . . . . . . . . . . 46
6.3.1. Securing the XMPP-Grid Transport Protocol . . . . . . 46
6.3.2. Securing XMPP-Grid Nodes . . . . . . . . . . . . . . 47
6.3.3. Securing XMPP-Grid Controllers . . . . . . . . . . . 48
6.3.4. Limit on search result size . . . . . . . . . . . . . 49
6.3.5. Cryptographically random session-id and
authentication checks for ARC . . . . . . . . . . . . 49
6.3.6. Securing the Certification Authority . . . . . . . . 49
6.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . 50
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 50
8. Evolution of XMPP-Grid . . . . . . . . . . . . . . . . . . . 51
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 51
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 51
10.1. Normative References . . . . . . . . . . . . . . . . . . 51
10.2. Informative References . . . . . . . . . . . . . . . . . 52
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 53
1. Introduction
This document describes the extensions made to Extensible Messaging
and Presence Protocol (XMPP) [RFC6120]that enables use of XMPP as a
transport protocol for collecting and distributing security telemetry
information between and among network platforms, endpoints, and most
any network connected device. Proposed use of this transport
protocol is for serving use-cases outlined by the Security Automation
and Continuous Monitoring (SACM) working group with the IETF.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Many of the terms used in this document are defined in
[I-D.ietf-sacm-terminology] and new ones referenced in this draft.
This document is being discussed on the sacm@ietf.org mailing list.
1.1. Glossary of Terms
AAA
Authentication, Authorization and Accounting.
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CA
Certification Authority.
Capability Provider
Providers who are capable of sharing information on XMPP-Grid.
CMDB
Configuration Management Database.
IDS
Intrusion Detection System.
IPS
Intrusion Prevention System.
JID
Jabber Identifier, native address of an XMPP entity.
MDM
Mobile Device Management.
NAC
Network Admission Control.
PDP
Policy Decision Point.
PEP
Policy Enforcement Point.
Presence
XMPP-Grid node availability and online status on XMPP-Grid.
Publisher
A capability provider sharing contet information to other devices
participating on XMPP-Grid.
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SIEM
Security Information and Event Management.
Subscriber
A device participating in XMPP-Grid and subscribing or consuming
information published by Publishers on XMPP-Grid.
Sub-Topics
Topic created by XMPP-Grid Controller under a capability
provider's topic based on message filter criteria expressed by
subscribers.
Topics
Contextual information channel created on XMPP-Grid where a
published message by the Publisher will be propagated by XMPP in
real-time to a set a subscribed devices.
VoIP
Voice over IP.
XMPP-Grid
Set of standards-based XMPP messages with extensions, intended for
use as a transport and communications protocol framework between
devices forming an information grid for serving SACM use-cases.
XMPP-Grid Controller
Centralized component of XMPP-Grid responsible for managing all
control plane operations.
XMPP-Grid Connection Agent
XMPP-Grid client library that a XMPP-Grid node implements to
connect and exchange information with other vendor devices on
XMPP-Grid.
XMPP-Grid Node
Platform or device that implements XMPP-Grid Connection Agent to
connect to XMPP-Grid and share or consume security data.
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1.2. What is XMPP-Grid?
XMPP-Grid is a set of standards-based XMPP messages with extensions.
It is intended for use as a transport and communications protocol
framework for devices that interconnect with each other, forming an
information grid for serving SACM use-cases.
XMPP-Grid enables secure, bi-directional multi-vendor exchange of
contextual information between IT infrastructure platforms such as
security monitoring and detection systems, network policy platforms,
asset and configuration management, identity and access management
platforms. XMPP-Grid can serve to exchange any contextual security
information, the relevance and scope for SACM is to use XMPP-Grid to
exchange Posture Assessment Information; thus this draft shall use
the terms interchangeably. XMPP-Grid is built on top of XMPP
[RFC6120], [RFC6121] which is an open IETF standard messaging routing
protocol used in commercial platforms such as Google Voice, Jabber
IM, Microsoft Messenger, AOL IM and a variety of IoT and XML message
routing services. XMPP is also being considered as a means to
transport IODEF [RFC5070]. XMPP-Grid is designed for orchestration
of data sharing between security platforms on a many-to-many basis
for millions of end systems.
XMPP-Grid provides a security data sharing framework that enables
multiple vendors to integrate to XMPP-Grid once, then both share and
consume data bi-directionally with many IT infrastructure platforms
and applications from a single consistent framework akin to a
network-wide information bus. This reduces the need to develop to
explicit, multiple platform-specific interfaces, thereby increasing
the breadth of platforms that can interface and share security data.
XMPP-Grid is also configurable thereby enabling partners to share
only security data they want to share and consume only information
relevant to their platform or use-case and to customize information
shared without revising the interfaces. XMPP-Grid is data-agnostic
enabling it to operate with virtually any data type or information
model, but does offer optional interoperability with the Interface
for Metadata Access Points (IF-MAP) [IF-MAP] or with IODEF, which are
commonly used information repositories for security data sharing.
1.3. Overview of XMPP-Grid
XMPP-Grid employs publish/subscribe/query operations brokered by a
controller, which enforces access control in the system. This
architecture controls what platforms can connect to the "grid" to
share ("publish") and/or consume ("subscribe" or "query") contextual
information ("Topics") (described in Section 3.3 and 3.5) such as
security data needed to support SACM use-cases. The control of
publish/subscribe/query operations is architecturally distinct from
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the actual sharing of the contextual information. Control functions
are split into a logical control plane, whereas information exchange
is considered a logical data plane. This separation enables
scalability and customizability.
XMPP-Grid defines an infrastructure protocol that hides the nuances
of the XMPP data plane protocol and makes the information sharing
models extensible with simple intuitive interfaces. XMPP-Grid Nodes
connect to the Grid using the XMPP-Grid Protocol. The XMPP-Grid
Protocol makes use of the XMPP transport protocol and introduces an
application layer protocol leveraging XML and XMPP extensions to
define the protocol.
The components of XMPP-Grid are:
o XMPP-Grid Controller (Controller): The Controller manages the
control plane of XMPP-Grid operations. As such it authenticates
and authorizes platforms connecting to the data exchange grid and
controls whether or not they can publish, subscribe or query
Topics of security data.
o XMPP-Grid Connection Agent (Connection Agent): The Connection
Agent enables the adopting Node to communicate with the Controller
and other vendor platforms that have adopted XMPP-Grid. Through
this communication privileges of the connecting platform--
authorization to connect, publish, subscribe, query--are
established. The Connection Agent is typically implemented as a
client library.
o XMPP-Grid Node (Node): A Node is a platform that has implemented
the Connection Agent so that it can connect to an XMPP-Grid
deployment to share and/or consume security data.
o Data Repository: This is the source of security data available on
the Grid and may be a network security platform, management
console, endpoint, etc. XMPP-Grid does not mandate a specific
information model, but instead remains open to transport
structured or unstructured data. Data may be supplied by the
security platform itself or by an external information repository.
o Topic: An XMPP-Grid Topic defines a type of security data that a
platform wants to share with other platform(s).
The operations carried out by XMPP-Grid to exchange security data
are:
o Grid Connect: This is a Controller operation that authenticates a
Node that has implemented the Connection Agent to establish a
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connection with the XMPP-Grid. Once authenticated, authorization
policies on the Controller establish a Node's privileges on the
XMPP-Grid such as the right to undertake publish, subscribe or
query operations explained below.
o Publish Topic: Security information is made available when a XMPP-
Grid enabled platform "publishes" a "Topic". This operation is
authorized by the Controller and communicated to the connecting
platform via the Connection Agent.
o Topic Discovery: Nodes on a XMPP-Grid discover Topics of security
data relevant to them by searching the Topic directory available
within the XMPP-Grid deployment. The Controller maintains such a
Topic directory for every instance of XMPP-Grid.
o Subscribe to Topic: A Node seeking to consume security information
"subscribes" to a Topic that provides the security information it
seeks to serve its use-case. This operation has its authorization
checked by the Controller and communicated with the connecting
platform via the Connection Agent.
o Query: This operation enables a Node to request a specific set of
security data regarding a specific asset (such as a specific user
endpoint) or bulk output history from a Topic over a specific span
of time. Such queries can be carried out node-to-node or by
querying a central data repository. Query structure is adaptable
to match the information model in use.
XMPP-Grid is used to exchange security context data between systems
on a 1-to-1, 1-to-many, or many-to-many basis. Security data shared
between these systems may use pre-negotiated non-standard/native data
formats or may utilize an optional common information repository with
a standardized data format, as may be specified by SACM. XMPP-Grid
is data format agnostic and accommodates transport of whatever format
the end systems agree upon.
XMPP-Grid can operate in the following deployment architectures:
o Broker-Flow: An XMPP-Grid control plane brokers the authorization
and redirects the Topic subscriber to Topic publisher directly.
In this architecture, the Controller only manages the connection;
the security data flow is directly between Nodes using data
formats negotiated out-of-band.
o Centralized Data-Flow: An XMPP-Grid maintains the data within its
optional centralized database. In this architecture, the
Controller provides a common information structure for use in
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formatting and storing security context data, such as IF-MAP, and
directly responds to Node publish and Subscribe requests.
o Proxy-Flow: An XMPP-Grid is acting as proxy, collecting the data
from the publisher(s) and presenting it to the subscriber
directly. This is used for ad-hoc queries.
Within the deployment architecture, XMPP-Grid may be used in any
combination of the following data exchange modes. The flexibility
afforded by the different modes enables security information to be
exchanged between systems in the method most suitable for serving a
given use-case.
o Continuous Topic update stream: This mode delivers in real-time
any data published to a Topic to the Nodes that are subscribed to
that Topic.
o Directed query: This mode enables Nodes to request a specific set
of security information regarding a specific asset, such as a
specific user endpoint.
o Bulk historic data query: This mode enables Nodes to request
transfer of past output from a Topic over a specific span of time.
1.4. Benefits of XMPP-Grid
Benefits of XMPP-Grid can be summarized on two fronts: 1) end-user
benefits, 2) benefits for adopting vendors.
Benefits for end-users deploying security services based on XMPP-Grid
security context information sharing capabilities are derived from
the results that come with standardization including:
o Consolidating relevant security event data from multiple systems
to the "right console at the right time".
o Cross-vendor interoperability out-of-the-box, when using a
standard data format.
o Coordinated security response across multiple products from
multiple vendors, ranging from endpoint security to AAA, NAC, IDS/
IPS, Data Loss Prevention, firewalls to infrastructure such as
SIEM, CMDB, physical access control systems.
o Customer product choice and flexibility. No need to buy all
security products from one vendor.
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Adopting XMPP-Grid security data sharing capabilities provides a
number of benefits for adopting vendors, especially when compared to
proprietary interfaces, such as:
o Integrate the XMPP-Grid Connection Agent once to interface with
many platforms, simultaneously by subscribing or publishing
relevant security data
o Security information shared is configurable (via Topics) based on
relevance to specific use-cases and platforms
o Only sharing relevant data enables both publishing and subscribing
platforms to scale their security data sharing by eliminating
excess, irrelevant data
o Integrated authorization and security ensures only appropriate
XMPP-Grid operations are executed by permitted platforms
o Ability to share security data in native or structured formats
enables data model flexibility for adopting vendors
o Flexibility, adaptability to evolve to address new use cases over
time. Utilize data-agnostic transport protocol or the extensible
schema that allows for easy support for vendor-specific data.
1.5. Example Workflow
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______________
| XMPP-Grid |
Authorize /| Controller |\Authorize
/ |____________| \
________/ ^ \_________
"I have location" |Location| | | APP |"I have app info"
"I need app & ID.."|________|\ | /|________|"I need loc & dev"
\ | /
_\___|_____/_____
|Continuous Flow|
<-----|---------------|------>
| Directed Query|
--/------|-----\-
/ | \
/ | \
__________/ | \__________
"I have sec events"| SIEM | V | PAP |"I have ID & dev-type"
"I need ID & dev"|________| ______________ |________|"I need loc & MDM"
| Device Mgr |
|____________|
"I have MDM Info!"
"I need location..."
Figure 1: Typical XMPP-Grid Workflow
a. XMPP-Grid Controller establishes a grid for platforms wanting to
exchange security data.
b. A platform (Node) with a source of security data requests
connection to the Grid.
c. Controller authenticates and establishes authorized privileges
(e.g. privilege to publish and/or subscribe to security data
Topics) for the requesting Node.
d. Node may either publish a security data Topic, subscribe to a
security data Topic, query a Node or Topic, or any combination of
these operations.
e. Publishing Nodes unicast Topic updates to the Grid in real-time.
The Grid handles replication and distribution of the Topic to
subscribing Nodes. A Node may publish multiple Topics, thereby
allowing for customized relevance of the security data shared.
f. Subscribing Nodes receive continuous real-time stream of updates
to the Topic to which they are subscribed.
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g. Any Node on the Grid may subscribe to any Topics published to the
Grid (as permitted by authorization policy), thereby allowing for
one-to-one, one-to-many and many-to-many meshed security data
sharing between Nodes.
2. Applicability of XMPP-Grid to SACM Use Cases
This section discusses the applicability of XMPP-Grid to the usage
scenarios defined in [I-D.ietf-sacm-use-cases].
Within the SACM use-cases, the working group has outlined four use-
cases and seven usage-scenarios. XMPP-Grid is applicable to each one
of the use-cases and usage-scenarios by following one of the three
main logical flows of XMPP-Grid as outlined in section 1.1.1. The
three flows are summarized here:
o Broker-Flow: XMPP-Grid brokers the authorization and redirects the
Topic subscriber to Topic publisher directly.
o Centralized Data-Flow: XMPP-Grid is maintaining the data within
its optional centralized database.
o Proxy-Flow: XMPP-Grid is acting as proxy, collecting the data from
the publisher(s) and presenting it to the subscriber directly.
This is used for ad-hoc queries.
Each of the seven defined usage-scenarios is listed below, along with
a summary of how XMPP-Grid is applicable to each use-case.
It is important to note that XMPP-Grid is data model agnostic, and
may use any information model to structure data between systems. The
most common standardized security information model deployed
currently is IF-MAP, which XMPP-Grid interoperates with today.
2.1. Applicability of XMPP-Grid to SACM Usage Scenarios
2.1.1. SACM Definition and Publication of Automatable Configuration
Checklists
XMPP-Grid is fully applicable to the usage-scenario 2.2.1 as defined
within the SACM use-cases document. As a vendor creates a new guide,
they would publish an entry describing the existence of the checklist
to the applicable Topic within XMPP-Grid. For the purposes of this
explanation, the Topic name will be "Guide".
Grid Nodes who are subscribed to the Topic, will receive the
notification of the Topic update. In response or on-demand, the Node
will query XMPP-Grid in order to initiate the downloading of the new
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guide(s). The Grid Controller authorizes the download and proceeds
to retrieve the guide(s) from the publisher, and transfers that
download to the subscriber.
Similarly, when an administrator publishes a new checklist, they
would publish an entry describing the existence of the checklist to
the applicable Topic within XMPP-Grid. For the purposes of this
explanation, the Topic name will be "Checklist".
Grid Nodes who are subscribed to the Topic, will receive the
notification of the Topic update. In response or on-demand, the
participating entity will query XMPP-Grid in order to initiate the
downloading of the new checklist(s). The Grid Controller authorizes
the download and proceeds to retrieve the checklist(s) from the
publisher, and transfers that download to the subscriber. This is an
example of XMPP-Grid in Proxy-Flow mode.
2.1.2. SACM Automated Checklist Verification
An Endpoint Management System (EMS) publishes a Topic to XMPP-Grid
defining itself as an owner of Endpoint Data. Other network services
that are interested in endpoint data may subscribe to the Topic on
Endpoint Data, which is authorized by the XMPP-Grid.
A Baseline Service is subscribed to the Endpoint Data Topic, and has
a need for that updated endpoint data. The Baseline Service
(subscriber) requests the data from the XMPP-Grid, which authorizes
the retrieval and informs the subscriber of the existence of data on
the EMS directly. In this instance, the data transfer has been
authorized and occurs directly between the subscriber and the EMS.
The subscriber has now created new checklists and published the
information to the checklist Topic in XMPP-Grid. A PDP is subscribed
to the Checklist Topic, and is notified of the new checklists. The
PDP requests the data from the XMPP-Grid, which in-turn authorizes
the download and brokers the direct communication between the
Baseline Service and the PDP Directly.
This usage scenario is an example of XMPP-Grid in the Broker-Flow.
It is also showing that single entities may act as both publisher and
subscriber with the XMPP-Grid simultaneously.
2.1.3. SACM Detection of Posture Deviations
A user disables the firewall on a managed endpoint, which in-turn
sends a notice to its managing Compliance Service. The Compliance
Service publishes and alert to the "Alert Topic" in XMPP-Grid. There
is an Assessment Service, which subscribes to the Alert Topic, and is
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therefore notified of the alert. The Assessment service consumes
that alert directly from the XMPP-Grid and triggers an immediate
assessment of the endpoint.
This is an example of XMPP-Grid centralized-data flow. While XMPP-
Grid is information model agnostic, in this scenario IF-MAP could be
used as the centralized data repository with XMPP-Grid providing the
transport in/out of the IF-MAP database..
2.1.4. SACM Endpoint Information Analysis and Reporting
There are endpoints that are uploading large quantities of data to a
Suspicious Server on Internet. The admin queries XMPP-Grid for the
posture of the endpoints. The XMPP-Grid responds with all the
publishers of that information along with the authorization to query
for the data. The admin application is now able to query the data
sources directly, which indicates that the applicable endpoints all
have certain applications installed. The admin is now able to pivot
the query and receive information on all other endpoints that have
the same application installed.
This usage scenario is an example of XMPP-Grid Broker-Flow.
2.1.5. SACM Asynchronous Compliance/Vulnerability Assessment at Ice
Station Zebra
A University Team at Ice Station Zebra registers their Equipment with
an Asset Management System. The university puts together a
collection request for all deployed assets, and sends the query to
the XMPP-Grid. The collection request is queued at the XMPP-Grid for
the next window of connectivity when the request is sent to the
deployed assets. The remote endpoints fulfill the request and queue
the results for the next return opportunity. The results are sent
back to the university, where they are compared against what is in
the Asset Management System already.
This is an example of XMPP-Grid centralized-data flow. While XMPP-
Grid is information model agnostic, in this scenario IF-MAP could be
used as the centralized data repository with XMPP-Grid providing the
transport in/out of the IF-MAP database.
2.1.6. SACM Identification and Retrieval of Guidance
There are multiple configuration services in the environment, each
populating a "guide" Topic in XMPP-Grid. The operator queries XMPP-
Grid in order to discover and consolidate a single list to be
compared. The XMPP-Grid replies with list of data stores, and
authorization to perform the queries directly to those data stores.
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As the Admin/Operator defines search criteria, the operator is able
to query the data stores directly for that content, only returning to
the centralized XMPP-Grid when authorization is required.
This usage scenario is an example of XMPP-Grid in the Broker-Flow
2.1.7. SACM Guidance Change Detection
An Operator identifies content that they desire to assess, and
subscribes to that content Topic with XMPP-Grid. When a change to
that content occurs, the Operator is notified. Additionally, the
operator may be sent a query response. Any Data Collection and
evaluation Activities will also trigger an update to the operator
(subscriber).
This usage scenario is an example of XMPP-Grid centralized-data flow.
While XMPP-Grid is information model agnostic, in this scenario IF-
MAP could be used as the centralized data repository with XMPP-Grid
providing the transport in/out of the IF-MAP database.
3. XMPP-Grid Architecture
XMPP-Grid is a communication fabric that facilitates secure sharing
of information between network elements and networked applications
connected to the fabric both in real time and on demand.
XMPP-Grid uses XMPP servers that operate as a cluster with message
routing between them, for data plane communication. XMPP-Grid uses a
control plane element, the XMPP-Grid Controller, that is an external
component of XMPP for centralized policy-based control plane.
--------------- --------------- ---------------
| XMPP-Grid | | XMPP-Grid | | XMPP-Grid |
| Controller | | Controller | | Controller |
| | | | | |
--------------- --------------- ---------------
| | |
| | |
--------------- --------------- ---------------
| XMPP Server | | XMPP Server | | XMPP Server |
| |---------| |--------| |
| | | | | |
--------------- --------------- ---------------
Figure 2: XMPP Server and XMPP-Grid Cluster Architecture
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The connected Nodes, with appropriate authorization privileges, can:
o Receive real-time events of the published messages from the
publisher through Topic subscriptions
o Make directed queries to other Nodes in the XMPP-Grid with
appropriate authorization from the Controller
o Negotiate out-of-band secure file transfer channel with the peer
This model enables flexible API usage depending on the Nodes'
contextual and time-sensitivity needs of security information.
3.1. XMPP Overview
XMPP is used as the foundation message routing protocol for
exchanging security data between systems across XMPP-Grid. XMPP is a
communications protocol for message-oriented middleware based on XML.
Designed to be extensible, the protocol uses de-centralized client-
server architecture where the clients connect to the servers securely
and the messages between the clients are routed through the XMPP
servers deployed within the cluster. XMPP has been used extensively
for publish-subscribe systems, file transfer, video, VoIP, Internet
of Things, Smart Grid Software Defined Networks (SDN) and other
collaboration and social networking applications. The following are
the 4 IETF specifications produced by XMPP working group:
o [RFC6120] Extensible Messaging and Presence Protocol (XMPP): Core
o [RFC6121] Extensible Messaging and Presence Protocol (XMPP):
Instant Messaging and Presence
o [RFC3922] Mapping the Extensible Messaging and Presence Protocol
(XMPP) to Common Presence and Instant Messaging (CPIM)
o [RFC3923] End-to-End Signing and Object Encryption for the
Extensible Messaging and Presence Protocol (XMPP)
XMPP offers several of the following salient features for building a
security data interexchange protocol:
o Open - standards-based, decentralized and federated architecture,
with no single point of failure
o Security - Supports domain segregations and federation. Offers
strong security via Simple Authentication and Security Layer
(SASL) [RFC4422] and Transport Layer Security (TLS) [RFC5246].
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o Real-time event management/exchange - using publish, subscribe
notifications
o Flexibility and Extensibility - XMPP is XML based and is easily
extensible to adapt to new use-cases. Custom functionality can be
built on top of it.
o Multiple information exchanges - XMPP offers multiple information
exchange mechanisms between the participating clients -
o
* Real-time event notifications through publish and subscribe.
* On-demand or directed queries between the clients communicated
through the XMPP server
* Facilitates out-of-band, direct communication between
participating clients
o Bi-directional - avoids firewall tunneling and avoids opening up a
new connection in each direction between client and server.
o Scalable - supports cluster mode deployment with fan-out and
message routing
o Peer-to-peer communications also enables scale - directed queries
and out-of-band file transfer support
o XMPP offers Node availability, Node service capability discovery,
and Node presence within the XMPP network. Nodes ability to
detect the availability, presence and capabilities of other
participating nodes eases turnkey deployment.
The XMPP extensions used in XMPP-Grid are now part (e.g. publish/
subscribe) of the main XMPP specification [RFC6120] and the presence
in [RFC6121]. A full list of XMPP Extension Protocols (XEPs)
[RFC6120] can be found in http://xmpp.org/extensions/xep-0001.html .
3.2. XMPP-Grid Protocol Extensions to XMPP
XMPP-Grid defines an infrastructure protocol that hides the nuances
of the XMPP data plane protocol and makes the information sharing
models extensible with simple intuitive APIs. XMPP-Grid Nodes
connect to the Grid using the XMPP-Grid Protocol. The XMPP-Grid
Protocol makes use of the XMPP transport protocol and introduces an
application layer protocol leveraging XML and XMPP extensions to
define the protocol. The capability providers on the Grid extend the
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XMPP-Grid Protocol infrastructure model and define capability
specific models and schemas, allowing a cleaner separation of
infrastructure and capabilities that can run on the infrastructure.
3.3. XMPP-Grid Controller Protocol Flow
At the heart of the XMPP-Grid network, the XMPP-Grid Controller
serves as the centralized policy-based control plane element managing
all Node authentications, authorizations, capabilities/Topics and
their subscription list. XMPP-Grid Controller manages all control
aspects of the Node communication (including management) with the
XMPP-Grid and other participating Nodes with mutual trust and
authorizations' enforcement. XMPP-Grid Controller is a component of
XMPP server and programs the data plane XMPP server with Node
accounts, account status, XMPP Topics that are dynamically created
and Topic subscriptions. This is analogous to File Transfer Protocol
(FTP) that has control and data plane communication phases. Once the
Node requests are authenticated and authorized in the control plane
phase by the Controller, the Controller removes itself from the data
flow. All data plane communication then occurs between the Nodes,
publishers and subscribers of XMPP Topics happen at the XMPP data
plane layer.
---------------- ---------------- ----------------
| Publi- | Node | | Grid | XMPP | | Node | Sub- |
| sher |client| | Ctrlr | Srvr | |client| scriber|
| | | | | | | | |
----------------- ----------------- -----------------
| Authen & allow Grid Ctrlr Comm | |
|<------------------------------>| |
| | | |
| |Publisher | |
| | Auth | |
| | Status | |
| |<---------| |
| | | |
| | | Authen & allow Grid Ctrlr |
| | | Communication |
| | |<------------------------->|
| | | |
| |Subscriber| |
| | Auth | |
| | Status & | |
| | Account | |
| |<---------| |
| | | |
| Author Publisher to | | |
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| Topic Sequence | | |
--- |<------------------->| | |
C | | | | |
O | | | Add | |
N | | |Publisher | |
T | | | to Topic | |
R | | |--------->| |
O | | | | |
L | | | Author Subscriber to Topic Sequence |
--- | |<------------------------------------>|
| | | |
| | Add | |
| |Subscriber| |
| | to Topic | |
| |--------->| |
----------------------------------------------------------------------
| | | |
| Publish Message to Topic | |
--- |-------------------------------->| |
| | | | |
I | | Publish Success Published Message to Subscriber |
N | |<----------------------------------------------------------->|
F | | | | |
R | | | | Subscribe Success |
A | | | |<--------------------------|
| | | | |
--- | | Topic & Publisher Discovery Request |
| |<-------------------------------------|
| | | |
| | Topic & Publisher JID Response |
| |------------------------------------->|
| | | |
| | Out-of-Band Bulk Dnld Query Reqeust |
| |<-------------------------------------|
| | | |
| | Out-of-Band Bulk Dnld Query Author |
| |------------------------------------->|
| | |
| Out-of-Band Data Bulk Byte Stream |
|<----------------------------------------------------------->|
Figure 3: XMPP Controller Message Flow
Through a centralized authorization model, XMPP-Grid Controller
provides -
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o Visibility into "who is connecting", "who is accessing what"
o Node account management with provisions to add, delete or disable
accounts, and with provisions to auto or manual approve Node
account approval requests during the Node registration phase
o Centralized, policy-based authorization, providing "who can do
what" for publish-subscribe, directed peer-to-peer queries or for
bulk out-of-band transfers between participating Nodes
o Topics and subscription list management with provision to enable
or disable Topics
o Dynamic creation of sub-Topics within the main Topic depending on
attributes of interest from the requesting Node
o Ability to perform message filters on the published messages
3.4. XMPP-Grid Node Connection Protocol Flow
Nodes connecting to XMPP-Grid go through the phases of
authentication, registration and authorization before they can
participate in information exchange on XMPP-Grid.
3.4.1. Authentication
The communication between the Node and the XMPP-Grid Controller is
cryptographically encrypted using TLS. XMPP-Grid uses X.509
certificate-based mutual authentication between the Nodes and
Controller. Internally, XMPP uses Simple Authentication and Security
Layer (SASL)[RFC4422] External mechanism to authenticate and
establish secure tunnel with the Nodes, allowing the XMPP-Grid
Controller to rely on this capability offered by XMPP. If the Node
certificate does not pass the validation process, the connection
establishment is terminated with the error messages defined by the
XMPP standard. On successful authentication, XMPP SASL component
extracts the Node certificate and Node username to the Controller for
registration.
3.4.2. Registration
Once a Node has been authenticated and a secure tunnel has been
successfully established, the Nodes will register their accounts with
the Controller and Nodes provide their username to the Controller as
part of the registration request. XMPP-Grid supports manual
registration (requires explicit approval of the Node account) and
mutual authentication trust-based auto-approval registration in order
to provide additional trust and usability options to the
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administrator. The administrator may map the Nodes to the Node
groups to add additional level of validation and trust, and enforce
Node group based authorization. This allows the certificate-
username-group trust to get uniquely establishment for each Node and
duplicate registration requests using the same username will be
rejected.
During the registration process, the Controller restricts all Node
communication with the XMPP-Grid and only Node to Controller
communication is allowed. Once the Node is successfully registered,
the Controller lifts the restriction and allows the Nodes to
communicate on XMPP-Grid after it passes the authorization phase. It
should be noted that the registered and authorized Nodes could
publish, subscribe or query to multiple XMPP Topics between login and
logout to XMPP-Grid. Multiple Node applications running on a Node
could use one XMPP-Grid Node to connect to XMPP-Grid. The XMPP-Grid
Node should support Node applications' subscription to Topics and
should multiplex messages on its connection to XMPP-Grid. If a Node
application wants to be identified explicitly on XMPP-Grid, a new
XMPP-Grid Node connection to XMPP-Grid is required.
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----------------- ---------------------------
| | | Grid | XMPP |
| Node | | Controller| Server |
| | | | |
----------------- ---------------------------
| | |
_____| | |
| | | |
Register | | | |
|---->| | |
| TLS Connect(username, cert) | |
|<------------------------------------------------------>|
| | |
| | Track |
| |(username,cert) |
| |<---------------|
|Register(username) | |
|-------------------------------------->| |
| |___ |
| | | Approve & |
| | | Authorize |
| |<--| Account |
| | |
| |Create User |
| |Account |
| |(username) |
| |--------------->|
| Registration Successful | |
|<--------------------------------------| |
| | |
| Login() | |
|-------------------------------------->| |
| | |
| Pub/Sub/Query | |
|<------------------------------------------------------>|
| | |
| | |
| Logout() | |
|-------------------------------------->| |
| | |
Figure 4: XMPP-Grid Node Registration
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3.4.3. Authorization
The registered Nodes send subscription requests to the Controller.
The Controller, depending on the defined authorization privileges,
grants permissions to subscribe and/or publish to a Topic at the
registration time. The Controller updates the XMPP data plane server
with the new subscriber information and its capability. Node
identity extracted from the request, group to which the Node is
assigned during account approval and Topic/capability to which the
permission is sought could be some of the ways to authorize Nodes and
their requests in XMPP-Grid. Similarly, the Controller authorizes
directed peer-to-peer or out-of-band requests from a requesting peer.
The destination peer has options to query back the Controller to
retrieve and enforce granular authorizations such as read-only,
write-only, read/write.
In a Query Authorization flow, the capability provider responding to
the query is responsible for enforcing the authorization decision.
It retrieves "is authorized" from the XMPP-Grid Controller. Based on
the result, the service either allows or disallows the flow from
continuing.
----------------- ----------------- -----------------
| Subscriber | | XMPP-Grid | | Publisher |
| | | | | |
----------------- ----------------- -----------------
| | |
| | |
| query request |
|------------------------------------------------->|
| | |____
| | | | extract
| | | | identity
| | |<---
| | |
| | is authorized? |
| | (identity, service) |
| |<------------------------|
| | |
| query response |
|<-------------------------------------------------|
| | |
Figure 5: Node Query Authorization Flow
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For Publish Authorization, prior to allowing a publish request by a
user, the XMPP-Grid Controller calls the rule evaluation engine
directly for "is authorized". Based this result, the Controller
either allows or disallowed the flow from continuing.
----------------- ----------------- -----------------
| Publisher | | XMPP-Grid | | XMPP |
| | | Controller | | Server |
----------------- ----------------- -----------------
| | |
| publish | |
|----------------------->|____ |
| | | extract |
| | | identity |
| |<--- |
| | |
| |____ |
| | | is authorized? |
| | | (identity,publish) |
| |<--- |
| | |
| | publish |
| |------------------------>|
| | |
Figure 6: Node Publish Authorization Flow
For Subscribe Authorization, prior to allowing a subscribe request by
a user, the XMPP-Grid Controller calls the rule evaluation engine
directly for "is authorized". Based this result, the Controller
either allows or disallowed the flow from continuing.
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----------------- ----------------- -----------------
| Subscriber | | XMPP-Grid | | XMPP |
| | | Controller | | Server |
----------------- ----------------- -----------------
| | |
| subscribe | |
|----------------------->|____ |
| | | extract |
| | | identity |
| |<--- |
| | |
| |____ |
| | | is authorized? |
| | | (identity,publish) |
| |<--- |
| | |
| | subscribe |
| |------------------------>|
| | |
Figure 7: Node Subscribe Authorization Flow
Bulk Data Query differs from other data transfer modes. Unlike with
other modes of communication that operate in-band with the XMPP-Grid,
bulk downloads occur out-of-band (over a different protocol, outside
of the connection that was established with the XMPP-Grid
Controller). Previously discussed authorization mechanisms are
therefore not appropriate in this context.
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----------------- ----------------- -----------------
| Subscriber | | XMPP-Grid | | Publisher |
| | | Controller | | |
----------------- ----------------- -----------------
| | |
| request |
|------------------------------------------------->|
| | |____ extract
| | | | cert
| | | | chain
| | |<---
| | is authorized |
| | (cert chain, service) |
| |<------------------------|
| | |
| response |
|<-------------------------------------------------|
| | |
Figure 8: Node Bulk Data Query Flow
Instead the bulk download service sends the certificate chain used by
a Node in the TLS connection to the XMPP-Grid Controller for purposes
of authenticating and authorizing the Node. Upon receiving a request
with a certificate chain, the Controller checks the issuing
certificate against the trust store, looks up the identity associated
with the certificate, evaluates the rules, and returns "is
authorized" to the service. Then the service can either allow or
disallow the flow from continuing.
3.5. XMPP-Grid Topics Protocol Flow
For each capability, XMPP-Grid supports extensibility through XML
schemas where the providers (publishers) of the capabilities define
the schemas for the data exchanged. The capability provider shall
also define the version, the available queries and notifications that
it can support. The capability provider publishes the messages to
one or more XMPP Topics, that it requests XMPP-Grid to create
dynamically, depending on:
a. If the capability provider has mutually exclusive schemas,
different Topics will be created where the capability provider
will be a publisher to each Topic with a separate schema.
b. For a given Topic, if the subscribers wants to receive filtered
attributes or attribute values in capability provider's published
data, XMPP-Grid Controller creates sub Topics to the main Topic
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based on the message filters expressed. XMPP-Grid Controller
enrolls the capability provider as the publisher and the
requesting subscribers based on the message filter criteria they
express. The capability provider will be the publisher to both
the main Topic and the sub-Topics.
c. In the case mentioned in (b) above, it is possible for the
capability provider to just publish on the main Topic and have
the XMPP-Grid Controller filter the published messages on the
Controller-side and deliver attributes and attribute values of
interest to the subscribers. Controller-side message filter
application and the specify mechanisms such as XPATH that can be
used for parsing the messages is beyond the scope of this
specification.
3.5.1. Topic Versioning
XMPP-Grid supports versioning to support forward and backward
compatible information models. The providers of capability include
the version number in the messages they publish and the receiving
Nodes can interpret the Topic version and process the attributes
accordingly. The expectation is any new version of a capability must
be of additive updates only. In other words, existing elements and
attributes cannot be changed, only new elements or attributes can be
added. This will enable nodes with older capability be able to
process newer version. The extra new elements or attributes will be
ignored. Instead of using the same Topic for all versions, it is
possible in XMPP-Grid to programmatically create separate Topics for
each version and allow them to be discovered and subscribed by the
Nodes.
In XMPP-Grid, versioning support applies equally to both publish/
subscribe, directed and out-of-band queries.
3.5.2. Topic Discovery
The Nodes connected to XMPP-Grid can query the Controller and get the
list of all capabilities/Topics running on XMPP-Grid. The XML
samples provided in XMPP-Grid Protocol section above provide
illustrations of Capability Query and Capability Provider Query.
3.5.3. Subtopics and Message Filters
XMPP-Grid supports semantic message filtering for Topics. The
content being published by a provider can be semantically grouped
into categories based on domain, location of endpoints for example.
The provider of a capability specifies whether it supports semantic
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filtering or not to the Controller at the subscribe time to the Topic
under consideration.
XMPP-Grid subscribers query the Controller and obtain the filtering
options available for each capability, and express their message
filtering criteria at subscription time. The Controller, for each
unique filter criteria specified by the subscribers, creates a new
sub Topic under the main capability Topic. All the subscribers with
the same filtering criteria will be subscribed to the Subtopic. The
set of filter criteria for a capability will be predefined by the
capability provider and could be based on the well-defined attributes
of the message.
----------------- --------------------------- --------------
| | | Grid | XMPP | | Capability |
| Node | | Controller| Server | | Provider |
| | | | | | |
----------------- --------------------------- --------------
| | | |
|Subscribe with filter | |
|------------------->|____ | |
| | | translate & | |
| | | validate | |
| |<---- filter | |
| |____ | |
| | | Check if sub-topic |
| | | for filter | |
| |<--- exists | |
| | | |
| |Create subtopic if doesn't exist |
| |--------------------->| |
| | | |
| |Add Pub & Sub to Sub-Topic |
| |--------------------->| |
| | | |
| |Notify Publisher | |
| |------------------------------------->|
| Subscribe Success | | |
|<-------------------| | |
| | | |
Figure 9: Subtopics and Information Filter Subscribe Operations Flow
The publisher will be responsible for applying the filter on the
message and publishing the message on the Topic and the Subtopic
based on the filter criteria. Filtering logic will be on the
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publisher, as the publisher understands the message content. XMPP-
Grid fabric is oblivious to the message content.
To avoid proliferation of new Subtopics, the capability provider
could express the configurable limit on the number of Subtopics that
can be created for its capability at registration time. The XMPP-
Grid Controller will perform periodic cleanup of Subtopics whenever
their subscription list reduces to 0.
In XMPP-Grid, message filters are provided to all APIs i.e. publish/
subscribe and directed query.
----------------- --------------------------- --------------
| Capability | | Grid | XMPP | | |
| Provider | | Controller| Server | | Node |
| | | | | | |
----------------- --------------------------- --------------
| | | |
| Register as Publisher | |
|------------------->| | |
| |Add Publisher to main | |
| |topic & all subtopics | |
| |--------------------->| |
|Return registration | | |
|success & list of | | |
|subtopics with | | |
|filtering criteria | | |
|<-------------------| | |
| | | |
|Publish message to | | |
|main topic | | |
|------------------->| | |
Check |____ |Publish message to | |
filtering| | |main topic | |
criteria & | |--------------------->| |
identity |<--- | | |
| | | |
|Publish message to | | |
|subtopic that matched filter | |
|------------------------------------------>| |
| | | Notify |
| | |-------------->|
Figure 10: Subtopic Publish Operations Flow
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3.6. XMPP-Grid Protocol Details
The XMPP-Grid Protocol provides provides an abstraction layer over
and above XMPP messages with the intent to provide intuitive
interfaces to the Nodes connecting to XMPP-Grid. Nodes connecting to
XMPP-Grid use the following interfaces (provided as XML samples)
offered by XMPP-Grid protocol to connect and participate in
information exchange on XMPP-Grid:
o Register the Node to XMPP-Grid: Node identified as
"Node2@domain.com/mac" sends the following Registration request to
XMPP-Grid controller.
<iq id="ay0tK-4" to="grid_Controller.jabber"
from="Node2@domain.com/syam-mac" type="get">
<grid xmlns='gi' type='request'>
<AccountQuery xmlns='com.domain.gi.gcl.Controller'>
<register></register></AccountQuery>
</grid>
</iq>
o Node login to XMPP-Grid: The following XML sample shows the Login
request from Node "Node2@domain.com/mac" to XMPP-Grid controller and
Login response returned by the XMPP-Grid controller to the Node.
// Request
<iq id="ay0tK-5" to="grid_Controller.jabber"
from="Node2@domain.com/mac" type="get">
<grid xmlns='gi' type='request'>
<AccountQuery xmlns='com.domain.gi.gcl.Controller'>
<login></login>
</AccountQuery>
</grid>
</iq>
// Response
<iq xmlns="jabber:client" to=" Node2@domain.com/mac"
from="grid_Controller.jabber" type="result" id="ay0tK-5">
<grid xmlns="gi" type="response">
<AccountQuery xmlns="com.domain.gi.gcl.Controller">
<login xmlns="">
<value xmlns:ns2="gi" xmlns:xsi=" xsi:nil="true" />
</login>
</AccountQuery>
</grid>
</iq>
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o Node logout from XMPP-Grid: The following XML sample shows the
Logout request sent by Node "Node2@domain.com/mac" to XMPP-Grid
controller.
<iq id="o47m2-8" to="grid_Controller.jabber"
from="Node2@domain.com/mac" type="get">
<grid xmlns='gi' type='request'>
<AccountQuery xmlns='com.domain.gi.gcl.Controller'>
<logout></logout>
</AccountQuery>
</grid>
</iq>
o Capability Discovery Query: The following XML sample shows the
Capability Discovery query request from Node "Node2@domain.com/mac"
to XMPP-Grid controller. The XMPP-Grid controller returns the list
of capabilities supported by XMPP-Grid and their versions as a
response to the Node's request.
// Request
<iq id="tVKqm-6" to="grid_Controller.jabber"
from="Node2@domain.com/mac" type="get">
<grid xmlns="xgrid" type="request">
<ns2:getCapabilityListRequest xmlns:ns2=" xmlns:ns4="
xmlns:ns3=" xmlns:ns5=" xmlns:ns6=" xmlns:ns7=" />
</grid>
</iq>
// Response
<iq from="grid_Controller.jabber" id="tVKqm-6"
to="Node2@domain.com/mac" type="result" xmlns="jabber:client">
<grid type="response" xmlns="xgrid">
<ns2:getCapabilityListResponse xmlns:ns2=" xmlns:ns3="
xmlns:ns4=" xmlns:ns5=" xmlns:ns6=" xmlns:ns7=">
<ns2:capability xmlns:xsi=
" xsi:type="ns5:TrustSecMetaDataCapability">
<ns2:id>0</ns2:id>
<ns2:name>TrustSecMetaDataCapability-1.0</ns2:name>
<ns2:version>1.0</ns2:version>
</ns2:capability>
<ns2:capability
xmlns:xsi=" xsi:type="ns5:EndpointProfileMetaDataCapability">
<ns2:id>0</ns2:id>
<ns2:name>
EndpointProfileMetaDataCapability-1.0</ns2:name>
<ns2:version>1.0</ns2:version>
</ns2:capability>
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<ns2:capability xmlns:xsi=
" xsi:type="ns5:IdentityGroupCapability">
<ns2:id>0</ns2:id>
<ns2:name>IdentityGroupCapability-1.0</ns2:name>
<ns2:version>1.0</ns2:version>
</ns2:capability>
<ns2:capability xmlns:ns9=" xmlns:xsi="
xsi:type="ns9:TDAnalysisServiceCapability">
<ns2:id>0</ns2:id>
<ns2:name>TDAnalysisServiceCapability-1.0</ns2:name>
<ns2:version>1.0</ns2:version>
</ns2:capability>
<ns2:capability xmlns:xsi=" xsi:type="
ns7:NetworkCaptureCapability">
<ns2:id>0</ns2:id>
<ns2:name>NetworkCaptureCapability-1.0</ns2:name>
<ns2:version>1.0</ns2:version>
</ns2:capability>
<ns2:capability xmlns:xsi=
" xsi:type="ns6:EndpointProtectionServiceCapability">
<ns2:id>0</ns2:id>
<ns2:name>
EndpointProtectionServiceCapability-1.0</ns2:name>
<ns2:version>1.0</ns2:version>
</ns2:capability>
<ns2:capability xmlns:xsi=
" xsi:type="ns4:GridControllerAdminServiceCapability">
<ns2:id>0</ns2:id>
<ns2:name>
GridControllerAdminServiceCapability-1.0</ns2:name>
<ns2:version>1.0</ns2:version>
</ns2:capability>
<ns2:capability xmlns:xsi=
" xsi:type="ns5:SessionDirectoryCapability">
<ns2:id>0</ns2:id>
<ns2:name>SessionDirectoryCapability-1.0</ns2:name>
<ns2:version>1.0</ns2:version>
</ns2:capability>
</ns2:getCapabilityListResponse>
</grid>
</iq>
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o Specific Capability Provider Query: The following XML sample shows
the Capability Provider hostname query request from Node
"Node2@domain.com/mac" to XMPP-Grid controller. XMPP-Grid controller
returns the hostname of the specific Capability Provider as a
response to the Node's request.
// Request
<iq id="996IL-8" to="grid_Controller.jabber"
from="Node2@domain.com/mac" type="get">
<grid xmlns='gi' type='request'>
<DiscoveryQuery xmlns='com.domain.gi.gcl.Controller'>
<find><param xsi:type="xs:string" xmlns:ns2="gi" xmlns:xs
=" xmlns:xsi=">com.domain.ise.session.SessionQuery
</param></find>
</DiscoveryQuery>
</grid>
</iq>
// Response
<iq from='grid_Controller.jabber' id='996IL-8'
to='Node2@domain.com/mac' type='result'
xmlns='jabber:client'>
<grid type='response' xmlns='gi'>
<DiscoveryQuery xmlns='com.domain.gi.gcl.Controller'>
<find xmlns=''><value xmlns:ns3='http://jaxb.dev.java.net/array'
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xsi:type='ns3:stringArray'>
<item>ise@syam-06.domain.com/syam-mac</item></value></find>
</DiscoveryQuery>
</grid>
</iq>
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o Register as a publisher to the Topic: The following XML sample
shows the Register as a Publisher request from a Node
"Node2@domain.com/mac" to XMPP-Grid controller.
<iq id="fD65a-6" to="grid_Controller.jabber"
from="Node2@domain.com/mac" type="get">
<grid xmlns="xgrid" type="request">
<ns2:initPublishRequest xmlns:ns2=" xmlns:ns4=
" xmlns:ns3=" xmlns:ns5=" xmlns:ns6=" xmlns:ns7=">
<ns2:capability xsi:type="ns5:SessionCapability"
xmlns:xsi=">
<ns2:id>0</ns2:id>
<ns2:version>1.0</ns2:version>
</ns2:capability>
</ns2:initPublishRequest>
</grid>
</iq>
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o Register as a subscriber to the Topic: The following XML sample
shows a subscription request made by Node "Node2@domain.com/mac" for
"SessionCapability" Topic to XMPP-Grid controller. On success,
determined by the Node's authorization privilege, XMPP-Grid
controller returns the Topic name, version and the Publishers'
hostname as a response to the Node's request.
// Subscribe Request
<iq id="lQJIT-6" to="grid_Controller.jabber"
from="Node2@domain.com/mac" type="get">
<grid xmlns="xgrid" type="request">
<ns2:subscribeRequest xmlns:ns2=" xmlns:ns4=" xmlns:ns3
=" xmlns:ns5=" xmlns:ns6=" xmlns:ns7=">
<ns2:capability xsi:type="ns5:SessionCapability"
xmlns:xsi=">
<ns2:id>0</ns2:id>
<ns2:version>1.0</ns2:version>
</ns2:capability>
</ns2:subscribeRequest>
</grid>
</iq>
// Subscribe Response
<iq from="grid_Controller.jabber" id=" lQJIT-6"
to="Node2@domain.com/mac" type="result" xmlns="jabber:client">
<grid type="response" xmlns="xgrid">
<ns2:subscribeResponse xmlns:ns2=
" xmlns:ns3=" xmlns:ns4=" xmlns:ns5="
xmlns:ns6=" xmlns:ns7=">
<ns2:topicName>SessionCapability-1.0</ns2:topicName>
<ns2:xmppDetails>
<ns2:jid>ise-mnt-XMPP-Grid-004@xgrid.domain.com/gcl
</ns2:jid>
<ns2:jid>ise-mnt-XMPP-Grid-005@xgrid.domain.com/gcl
</ns2:jid>
</ns2:xmppDetails>
</ns2:subscribeResponse>
</grid>
</iq>
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o Peer-to-Peer Directed Query: The following XML sample shows a peer-
to-peer directed query request made by Node "Node2@domain.com/mac" to
other XMPP-Grid participating Node "grid_Controller.jabber", seeking
identity group information for a specific user "user1".
"grid_Controller.jabber" returns the list of identity groups "user1"
belongs as a response to the request.
// Query Request
<iq id="kR0YY-8" to="grid_Controller.jabber"
from="Node2@domain.com/mac" type="get">
<grid xmlns="xgrid" type="request">
<ns5:getIdentityGroupRequest xmlns:ns2=" xmlns:ns4="
xmlns:ns3=" xmlns:ns5=" xmlns:ns6=" xmlns:ns7=">
<ns5:user>
<ns2:name>user1</ns2:name>
</ns5:user>
</ns5:getIdentityGroupRequest>
</grid>
</iq>
// Query Response
<iq from="grid_Controller.jabber"
id=" kR0YY-8" to="Node2@domain.com/mac" type="result">
<grid type="response" xmlns="xgrid">
<ns5:getIdentityGroupResponse xmlns:ns2=" xmlns:ns3=
" xmlns:ns4=" xmlns:ns5=" xmlns:ns6=" xmlns:ns7=">
<ns5:user>
<ns2:name>user1</ns2:name>
<ns3:groupList>
<ns3:object>
<ns2:name>User Identity Groups:Employee
</ns2:name>
<ns3:type>Identity</ns3:type>
</ns3:object>
</ns3:groupList>
</ns5:user>
</ns5:getIdentityGroupResponse>
</grid>
</iq>
4. XMPP-Grid Compatibility with IF-MAP Information Model
As mentioned throughout this document, XMPP-Grid is information model
and data format agnostic, as it focuses on transport of security
context data. There are, however, deployment scenarios where
accessing data in a common format in a consistent information model
will be required for serving SACM use-cases. The most prevalent
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standards-based model for such deployments is IF-MAP, thus an XMPP-
Grid/IF-MAP compatibility discussion is salient for this document.
The Trusted Network Connect Working Group (TNC-WG) has defined an
open solution architecture [IF-MAP] that enables network operators to
enforce policies regarding the security state of endpoints in order
to determine whether to grant access to a requested network
infrastructure. Part of the TNC architecture is IF-MAP, a standard
interface between the Metadata Access Point and other elements of the
TNC architecture. Readers who wish to understand in detail and
implement IF-MAP are encouraged to review the following documents:
o [IF-MAP]Trusted Computing Group, TNC Architecture for
Interoperability, Revision 1.5, May 2012
o [IF-MAP-SOAP]Trusted Computing Group, TNC IF-MAP Binding for SOAP,
Revision 2.2, March 2014
o [IF-MAP-NETSEC]Trusted Computing Group, TNC IF-MAP Metadata for
Network Security, Revision 1.0, August 2010
o [IF-MAP-ICS]Trusted Computing Group, TNC IF-MAP Metadata for ICS,
Security, Revision 1.0, October 2012
From a compatibility perspective, XMPP-Grid can substitute the SOAP-
based IF-MAP standard interface between the MAP server and other
elements in the network, thereby providing the information transport
between IF-MAP clients. This substitution delivers greater
scalability and timely data, as well as backwards compatibility with
IF-MAP deployments. The IF-MAP data data (Topics and Subtopics can
be created based on IF-MAP data models) and operation models
(interfaces, message filters could be defined for the Topics and
Subtopics based on the IF-MAP operations supported for the use-cases
developed for use-cases such as network security can be overlaid on
XMPP-Grid transport thereby achieving model consistency for both IF-
MAP enabled and XMPP-Grid enabled network deployment scenarios. The
MAP Server will be the participant in both the IF-MAP enabled network
and the XMPP-Grid enabled network serving as aggregator and publisher
of information.
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IF-MAP Enabled Devices
____________ ___________ _____________
|__________|_ | | IF-MAP | Flow |
|| _________|_ | |<-------->|Controllers|
|| | | IF-MAP | | |___________|
-|_| PDP |<-------->| |
|_________| | | _____________
| MAP | IF-MAP | |
____________ | Server |<-------->| Sensors |
|__________|_ | | |___________|
|| _________|_ | | _____________
|| | | IF-MAP | | IF-MAP | |
-|_| PEP |<-------->| |<-------->| Others |
|_________| |_________| |___________|
^
|
| Grid
XMPP-Grid Enabled Devices |
____________ _____V_____ _____________
|__________|_ | | Grid | Flow |
|| _________|_ | |<-------->|Controllers|
|| | | Grid | | |___________|
-|_| PDP |<-------->| Grid |
|_________| | Server | _____________
| Cluster | Grid | |
____________ | |<-------->| Sensors |
|__________|_ | | |___________|
|| _________|_ |_________| _____________
|| | | | |
-|_| PEP | GRID | Others |
|_________|<----------------------------->|___________|
Figure 11: XMPP-Grid and IF-MAP Interoperability
The MAP server will be a XMPP-Grid Node connected to the XMPP-Grid
Controller. The MAP server will play the role of subscribers and/or
publishers depending on the MAP graphs and the contextual metadata to
be aggregated and/or published.
4.1. MAP Server as XMPP-Grid Subscriber for Metadata Aggregation
The MAP Server will be a subscriber when aggregating metadata from
various XMPP-Grid-enabled PEPs and PDPs in the network. Topics will
be created in XMPP-Grid depending on the metadata to be aggregated,
how relational or disjoint the metadata types, metadata-identifier
linkages in IF-MAP graph are and the publishers of the data such as
the Access Requestors, PEPs and PDPs. As discussed in the Topics
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section earlier, XMPP-Grid provides the ability to the Capability
provider to create main Topics and Subtopics. The MAP server will be
a subscriber to all of the Topics created for such purposes of
aggregation. It is the responsibility of the MAP server to use the
subscribed metadata to build and manage the MAP graphs.
XMPP-Grid architecture allows multiple MAP servers to be subscribers
to the Topics and also other network elements such as Flow
Controllers and Sensors to directly consume information from the
sources. This enables a complete decentralized architecture for IF-
MAP for metadata aggregation where the MAP Server need not always be
the sole publisher of metadata for the MAP graph. With such approach
it will be possible for time-sensitive subscribers to directly
consume information from the sources and use the MAP server for query
and search purposes only, enabling the MAP servers to scale
significantly. This also allows aggregation of metadata based on
domains where MAP server can aggregate and publish metadata based on
domain, and subscribers could use message filters such as domain,
location to receive only metadata of interest to them.
Region 1 Region 2
___________ ___________
| | | |
| MAP | | MAP |
| Server | | Server |
____________ | | | | ___________
|__________|_ |_________| |_________| _|_________|
|| _________|_ ^ ^ _|_________||
|| | | Grid | | Grid | ||-
-|_| PDP |<-----------| |Grid Grid| |----------->| PDP |-
|_________| | | | | |_________|
____________ __V__V_____ ______V__V__ ___________
|__________|_ | | | | _|_________|
|| _________|_ | | | | _|_________||
|| | | Grid | | | | Grid | ||-
-|_| PEP |<-------->| | | |<-------->| PEP |-
|_________| | | | | |_________|
_____________ | Grid | Grid | Grid | _____________
| Flow | Grid | Server |<---->| Server | Grid | Flow |
|Controllers|<--------->| | | |<--------->|Controllers|
|___________| | | | | |___________|
_____________ | | | | _____________
| | Grid | | | | Grid | |
| Sensors |<--------->| | | |<--------->| Sensors |
|___________| |_________| |__________| |___________|
Figure 12: XMPP-Grid Bridging Multiple IF-MAP Instances
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4.2. MAP Server as XMPP-Grid Publisher for Metadata Dissemination
MAP Server could publish the MAP graph attribute changes to
interested subscribers such as Flow Controllers, Sensors in the
following ways
a. MAP Server to publish all attribute changes of a MAP graph on a
main Topic to which the interested network elements participate
as subscribers. The subscribers will be able to get real-time
notifications through Publish-Subscribe and make on-demand peer-
to-peer directed or bulk queries depending on their authorization
privileges.
b. In addition, MAP server, at registration time with XMPP-Grid,
could register the MAP graph's filtering criteria as a Publisher
with XMPP-Grid. The filtering criteria of a MAP graph could be
based on a combination of -
A. metadata types
B. metadata-identifier linkage attributes
C. metadata class
D. existing IF-MAP search criteria
As discussed in the Topics section, XMPP-Grid Controller will create
Subtopics and manage the Subtopics through the lifecycle based on the
subscription list. The MAP Server and XMPP-Grid applies the message
filters to publish-subscribe, directed or bulk queries made by the
subscribers.
5. IANA Considerations
IANA Considerations to be determined
6. Security Considerations
A XMPP-Grid Controller serves as an controlling broker for XMPP-Grid
Nodes such as Enforcement Points, Policy Servers, CMDBs, and Sensors,
using a publish-subscribe-search model of information exchange and
lookup. By increasing the ability of XMPP-Grid Nodes to learn about
and respond to security-relevant events and data, XMPP-Grid can
improve the timeliness and utility of the security system. However,
this integrated security system can also be exploited by attackers if
they can compromise it. Therefore, strong security protections for
XMPP-Grid are essential.
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This section provides a security analysis of the XMPP-Grid transport
protocol and the architectural elements that employ it, specifically
with respect to their use of this protocol. Three subsections define
the trust model (which elements are trusted to do what), the threat
model (attacks that may be mounted on the system), and the
countermeasures (ways to address or mitigate the threats previously
identified).
6.1. Trust Model
The first step in analyzing the security of the XMPP-Grid transport
protocol is to describe the trust model, listing what each
architectural element is trusted to do. The items listed here are
assumptions, but provisions are made in the Threat Model and
Countermeasures sections for elements that fail to perform as they
were trusted to do.
6.1.1. Network
The network used to carry XMPP-Grid messages is trusted to:
o Perform best effort delivery of network traffic
The network used to carry XMPP-Grid messages is not expected
(trusted) to:
o Provide confidentiality or integrity protection for messages sent
over it
o Provide timely or reliable service
6.1.2. XMPP-Grid Nodes
Authorized XMPP-Grid Nodes are trusted to:
o Preserve the confidentiality of sensitive data retrieved via the
XMPP-Grid Controller
6.1.3. XMPP-Grid Controller
The XMPP-Grid Controller is trusted to:
o Broker requests for data and enforce authorization of access to
this data throughout its lifecycle
o Perform service requests in a timely and accurate manner
o Create and maintain accurate operational attributes
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o Only reveal data to and accept service requests from authorized
parties
The XMPP-Grid Controller is not expected (trusted) to:
o Verify the truth (correctness) of data
6.1.4. Certification Authority
The Certification Authority (CA) that issues certificates for the
XMPP-Grid Controller and/or XMPP-Grid Nodes (or each CA, if there are
several) is trusted to:
o Protect the confidentiality of the CA's private key
o Ensure that only proper certificates are issued and that all
certificates are issued in accordance with the CA's policies
o Revoke certificates previously issued when necessary
o Regularly and securely distribute certificate revocation
information
o Promptly detect and report any violations of this trust so that
they can be handled
The CA is not expected (trusted) to:
o Issue certificates that go beyond name constraints or other
constraints imposed by a relying party or a cross-certificate
6.2. Threat Model
To secure the XMPP-Grid transport protocol and the architectural
elements that implement it, this section identifies the attacks that
can be mounted against the protocol and elements.
6.2.1. Network Attacks
A variety of attacks can be mounted using the network. For the
purposes of this subsection the phrase "network traffic" should be
taken to mean messages and/or parts of messages. Any of these
attacks may be mounted by network elements, by parties who control
network elements, and (in many cases) by parties who control network-
attached devices.
o Network traffic may be passively monitored to glean information
from any unencrypted traffic
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o Even if all traffic is encrypted, valuable information can be
gained by traffic analysis (volume, timing, source and destination
addresses, etc.)
o Network traffic may be modified in transit
o Previously transmitted network traffic may be replayed
o New network traffic may be added
o Network traffic may be blocked, perhaps selectively
o A "Man In The Middle" (MITM) attack may be mounted where an
attacker interposes itself between two communicating parties and
poses as the other end to either party or impersonates the other
end to either or both parties
o Resist attacks (including denial of service and other attacks from
XMPP-Grid Nodes)
o Undesired network traffic may be sent in an effort to overload an
architectural component, thus mounting a denial of service attack
6.2.2. XMPP-Grid Nodes
An unauthorized XMPP-Grid Nodes (one which is not recognized by the
XMPP-Grid Controller or is recognized but not authorized to perform
any actions) cannot mount any attacks other than those listed in the
Network Attacks section above.
An authorized XMPP-Grid Node, on the other hand, can mount many
attacks. These attacks might occur because the XMPP-Grid Node is
controlled by a malicious, careless, or incompetent party (whether
because its owner is malicious, careless, or incompetent or because
the XMPP-Grid Node has been compromised and is now controlled by a
party other than its owner). They might also occur because the XMPP-
Grid Node is running malicious software; because the XMPP-Grid Node
is running buggy software (which may fail in a state that floods the
network with traffic); or because the XMPP-Grid Node has been
configured improperly. From a security standpoint, it generally
makes no difference why an attack is initiated. The same
countermeasures can be employed in any case.
Here is a list of attacks that may be mounted by an authorized XMPP-
Grid Node:
o Cause many false alarms or otherwise overload the XMPP-Grid
Controller or other elements in the network security system
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(including human administrators) leading to a denial of service or
disabling parts of the network security system
o Omit important actions (such as posting incriminating data),
resulting in incorrect access
o Use confidential information obtained from the XMPP-Grid
Controller to enable further attacks (such as using endpoint
health check results to exploit vulnerable endpoints)
o Advertise data crafted to exploit vulnerabilities in the XMPP-Grid
Controller or in other XMPP-Grid Nodes, with a goal of
compromising those systems
o Issue a search request or set up a subscription that matches an
enormous result, leading to resource exhaustion on the XMPP-Grid
Controller, the publishing XMPP-Grid Node, and/or the network
o Establish a communication channel using another XMPP-Grid Node's
session-id
Dependencies of or vulnerabilities of authorized XMPP-Grid Nodes may
be exploited to effect these attacks. Another way to effect these
attacks is to gain the ability to impersonate a XMPP-Grid Node
(through theft of the XMPP-Grid Node's identity credentials or
through other means). Even a clock skew between the XMPP-Grid Node
and XMPP-Grid Controller can cause problems if the XMPP-Grid Node
assumes that old XMPP-Grid Node data should be ignored.
6.2.3. XMPP-Grid Controllers
An unauthorized XMPP-Grid Controller (one which is not trusted by
XMPP-Grid Nodes) cannot mount any attacks other than those listed in
the Network Attacks section above.
An authorized XMPP-Grid Controller can mount many attacks. Similar
to the XMPP-Grid Node case described above, these attacks might occur
because the XMPP-Grid Controller is controlled by a malicious,
careless, or incompetent party (either a XMPP-Grid Controller
administrator or an attacker who has seized control of the XMPP-Grid
Controller). They might also occur because the XMPP-Grid Controller
is running malicious software, because the XMPP-Grid Controller is
running buggy software (which may fail in a state that corrupts data
or floods the network with traffic), or because the XMPP-Grid
Controller has been configured improperly.
All of the attacks listed for XMPP-Grid Node above can be mounted by
the XMPP-Grid Controller. Detection of these attacks will be more
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difficult since the XMPP-Grid Controller can create false operational
attributes and/or logs that imply some other party created any bad
data.
Additional XMPP-Grid Controller attacks may include:
o Expose different data to different XMPP-Grid Nodes to mislead
investigators or cause inconsistent behavior
o Mount an even more effective denial of service attack than a
single XMPP-Grid Node could
o Obtain and cache XMPP-Grid Node credentials so they can be used to
impersonate XMPP-Grid Nodes even after a breach of the XMPP-Grid
Controller is repaired
o Obtain and cache XMPP-Grid Controller administrator credentials so
they can be used to regain control of the XMPP-Grid Controller
after the breach of the XMPP-Grid Controller is repaired
Dependencies of or vulnerabilities of the XMPP-Grid Controller may be
exploited to obtain control of the XMPP-Grid Controller and effect
these attacks.
6.2.4. Certification Authority
A Certification Authority trusted to issue certificates for the XMPP-
Grid Controller and/or XMPP-Grid Nodes can mount several attacks:
o Issue certificates for unauthorized parties, enabling them to
impersonate authorized parties such as the XMPP-Grid Controller or
a XMPP-Grid Node. This can lead to all the threats that can be
mounted by the certificate's subject.
o Issue certificates without following all of the CA's policies.
Because this can result in issuing certificates that may be used
to impersonate authorized parties, this can lead to all the
threats that can be mounted by the certificate's subject.
o Fail to revoke previously issued certificates that need to be
revoked. This can lead to undetected impersonation of the
certificate's subject or failure to revoke authorization of the
subject, and therefore can lead to all of the threats that can be
mounted by that subject.
o Fail to regularly and securely distribute certificate revocation
information. This may cause a relying party to accept a revoked
certificate, leading to undetected impersonation of the
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certificate's subject or failure to revoke authorization of the
subject, and therefore can lead to all of the threats that can be
mounted by that subject. It can also cause a relying party to
refuse to proceed with a transaction because timely revocation
information is not available, even though the transaction should
be permitted to proceed.
o Allow the CA's private key to be revealed to an unauthorized
party. This can lead to all the threats above. Even worse, the
actions taken with the private key will not be known to the CA.
o Fail to promptly detect and report errors and violations of trust
so that relying parties can be promptly notified. This can cause
the threats listed earlier in this section to persist longer than
necessary, leading to many knock-on effects.
6.3. Countermeasures
Below are countermeasures for specific attack scenarios to the XMPP-
Grid infrastructure.
6.3.1. Securing the XMPP-Grid Transport Protocol
To address network attacks, the XMPP-Grid transport protocol
described in this document requires that the XMPP-Grid messages MUST
be carried over TLS (minimally TLS 1.2 [RFC5246]) as described in
[RFC2818]. The XMPP-Grid Node MUST verify the XMPP-Grid Controller's
certificate and determine whether the XMPP-Grid Controller is trusted
by this XMPP-Grid Node before completing the TLS handshake. The
XMPP-Grid Controller MUST authenticate the XMPP-Grid Node either
using mutual certificate-based authentication in the TLS handshake or
using Basic Authentication as described in IETF RFC 2617. XMPP-Grid
Controller MUST use Simple Authentication and Security Layer (SASL),
described in [RFC4422], to support the aforesaid authentication
mechanisms. SASL offers authentication mechanism negotiations
between the XMPP-Grid Controller and XMPP-Grid node during the
connection establishment phase. XMPP-Grid Nodes and XMPP-Grid
Controllers using mutual certificate-based authentication SHOULD each
verify the revocation status of the other party. All XMPP-Grid
Controllers and XMPP-Grid Nodes MUST implement both mutual
certificate-based authentication and Basic Authentication. The
selection of which XMPP-Grid Node authentication technique to use in
any particular deployment is left to the administrator.
An XMPP-Grid Controller MAY also support a local, configurable set of
Basic Authentication userid-password pairs. If so, it is
implementation dependent whether a XMPP-Grid Controller ends a
session when an administrator changes the configured password. Since
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Basic Authentication has many security disadvantages (especially the
transmission of reusable XMPP-Grid Node passwords to the XMPP-Grid
Controller), it SHOULD only be used when absolutely necessary. Per
the HTTP specification, when basic authentication is in use, a XMPP-
Grid Controller MAY respond to any request that lacks credentials
with an error code similar to HTTP code 401. A XMPP-Grid Node SHOULD
avoid this code by submitting basic auth credentials with every
request when basic authentication is in use. If it does not do so, a
XMPP-Grid Node MUST respond to this code by resubmitting the same
request with credentials (unless the XMPP-Grid Node is shutting
down).
As XMPP uses TLS as the transport and security mechanisms, it is
understood that best practices such as those in
[I-D.ietf-uta-tls-bcp] are followed.
These protocol security measures provide protection against all the
network attacks listed in the above document section except denial of
service attacks. If protection against these denial of service
attacks is desired, ingress filtering, rate limiting per source IP
address, and other denial of service mitigation measures may be
employed. In addition, a XMPP-Grid Controller MAY automatically
disable a misbehaving XMPP-Grid Node.
6.3.2. Securing XMPP-Grid Nodes
XMPP-Grid Nodes may be deployed in locations that are susceptible to
physical attacks. Physical security measures may be taken to avoid
compromise of XMPP-Grid Nodes, but these may not always be practical
or completely effective. An alternative measure is to configure the
XMPP-Grid Controller to provide read-only access for such systems.
The XMPP-Grid Controller SHOULD also include a full authorization
model so that individual XMPP-Grid Nodes may be configured to have
only the privileges that they need. The XMPP-Grid Controller MAY
provide functional templates so that the administrator can configure
a specific XMPP-Grid Node as a DHCP server and authorize only the
operations and metadata types needed by a DHCP server to be permitted
for that XMPP-Grid Node. These techniques can reduce the negative
impacts of a compromised XMPP-Grid Node without diminishing the
utility of the overall system.
To handle attacks within the bounds of this authorization model, the
XMPP-Grid Controller MAY also include rate limits and alerts for
unusual XMPP-Grid Node behavior. XMPP-Grid Controllers SHOULD make
it easy to revoke a XMPP-Grid Node's authorization when necessary.
Another way to detect attacks from XMPP-Grid Nodes is to create fake
entries in the available data (honeytokens) which normal XMPP-Grid
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Nodes will not attempt to access. The XMPP-Grid Controller SHOULD
include auditable logs of XMPP-Grid Node activities.
To avoid compromise of XMPP-Grid Node, XMPP-Grid Node SHOULD be
hardened against attack and minimized to reduce their attack surface.
They SHOULD go through a TNC handshake to verify the integrity of the
XMPP-Grid Node, and SHOULD, if feasible, utilize a Trusted Platform
Module (TPM) for identity and/or integrity measurements of the XMPP-
Grid Node within a TNC handshake. They should be well managed to
minimize vulnerabilities in the underlying platform and in systems
upon which the XMPP-Grid Node depends. Personnel with administrative
access should be carefully screened and monitored to detect problems
as soon as possible.
6.3.3. Securing XMPP-Grid Controllers
Because of the serious consequences of XMPP-Grid Controller
compromise, XMPP-Grid Controllers SHOULD be especially well hardened
against attack and minimized to reduce their attack surface. They
SHOULD go through a regular TNC handshake to verify the integrity of
the XMPP-Grid Controller, and SHOULD utilize a Trusted Platform
Module (TPM) for identity and/or integrity measurements of the XMPP-
Grid Node within a TNC handshake. They should be well managed to
minimize vulnerabilities in the underlying platform and in systems
upon which the XMPP-Grid Controller depends. Network security
measures such as firewalls or intrusion detection systems may be used
to monitor and limit traffic to and from the XMPP-Grid Controller.
Personnel with administrative access should be carefully screened and
monitored to detect problems as soon as possible. Administrators
should not use password-based authentication but should instead use
non-reusable credentials and multi-factor authentication (where
available). Physical security measures SHOULD be employed to prevent
physical attacks on XMPP-Grid Controllers.
To ease detection of XMPP-Grid Controller compromise should it occur,
XMPP-Grid Controller behavior should be monitored to detect unusual
behavior (such as a reboot, a large increase in traffic, or different
views of an information repository for similar XMPP-Grid Nodes).
XMPP-Grid Nodes should log and/or notify administrators when peculiar
XMPP-Grid Controller behavior is detected. To aid forensic
investigation, permanent read-only audit logs of security-relevant
information (especially administrative actions) should be maintained.
If XMPP-Grid Controller compromise is detected, a careful analysis
should be performed of the impact of this compromise. Any reusable
credentials that may have been compromised should be reissued.
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6.3.4. Limit on search result size
While XMPP-Grid is designed for high scalability to 100,000s of
Nodes, an XMPP-Grid Controller MAY establish a limit to the amount of
data it is willing to return in search or subscription results. This
mitigates the threat of a XMPP-Grid Node causing resource exhaustion
by issuing a search or subscription that leads to an enormous result.
6.3.5. Cryptographically random session-id and authentication checks
for ARC
A XMPP-Grid Controller SHOULD ensure that the XMPP-Grid Node
establishing an ARC is the same XMPP-Grid Node as the XMPP-Grid Node
that established the corresponding SSRC. The XMPP-Grid Controller
SHOULD employ both of the following strategies:
o session-ids SHOULD be cryptographically random
o The HTTPS transport for the SSRC and the ARC SHOULD be
authenticated using the same credentials. SSL session resumption
MAY be used to establish the ARC based on the SSRC SSL session.
6.3.6. Securing the Certification Authority
As noted above, compromise of a Certification Authority (CA) trusted
to issue certificates for the XMPP-Grid Controller and/or XMPP-Grid
Nodes is a major security breach. Many guidelines for proper CA
security have been developed: the CA/Browser Forum's Baseline
Requirements, the AICPA/CICA Trust Service Principles, etc. The CA
operator and relying parties should agree on an appropriately
rigorous security practices to be used.
Even with the most rigorous security practices, a CA may be
compromised. If this compromise is detected quickly, relying parties
can remove the CA from their list of trusted CAs, and other CAs can
revoke any certificates issued to the CA. However, CA compromise may
go undetected for some time, and there's always the possibility that
a CA is being operated improperly or in a manner that is not in the
interests of the relying parties. For this reason, relying parties
may wish to "pin" a small number of particularly critical
certificates (such as the certificate for the XMPP-Grid Controller).
Once a certificate has been pinned, the relying party will not accept
another certificate in its place unless the Administrator explicitly
commands it to do so. This does not mean that the relying party will
not check the revocation status of pinned certificates. However, the
Administrator may still be consulted if a pinned certificate is
revoked, since the CA and revocation process are not completely
trusted.
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6.4. Summary
XMPP-Grid's considerable value as a broker for security-sensitive
data exchange distribution also makes the protocol and the network
security elements that implement it a target for attack. Therefore,
strong security has been included as a basic design principle within
the XMPP-Grid design process.
The XMPP-Grid transport protocol provides strong protection against a
variety of different attacks. In the event that a XMPP-Grid Node or
XMPP-Grid Controller is compromised, the effects of this compromise
have been reduced and limited with the recommended role-based
authorization model and other provisions, and best practices for
managing and protecting XMPP-Grid systems have been described. Taken
together, these measures should provide protection commensurate with
the threat to XMPP-Grid systems, thus ensuring that they fulfill
their promise as a network security clearing-house.
7. Privacy Considerations
XMPP-Grid Nodes may publish information about endpoint health,
network access, events (which may include information about what
services an endpoint is accessing), roles and capabilities, and the
identity of the end user operating the endpoint. Any of this
published information may be queried by other XMPP-Grid Nodes and
could potentially be used to correlate network activity to a
particular end user.
Dynamic and static information brokered by a XMPP-Grid Controller,
ostensibly for purposes of correlation by XMPP-Grid Nodes for
intrusion detection, could be misused by a broader set of XMPP-Grid
Nodes which hitherto have been performing specific roles with strict
well-defined separation of duties.
Care should be taken by deployers of XMPP-Grid to ensure that the
information published by XMPP-Grid Nodes does not violate agreements
with end users or local and regional laws and regulations. This can
be accomplished either by configuring XMPP-Grid Nodes to not publish
certain information or by restricting access to sensitive data to
trusted XMPP-Grid Nodes. That is, the easiest means to ensure
privacy or protect sensitive data, is to omit or not share it at all.
Another consideration for deployers is to enable end-to-end
encryption to ensure the data is protected from the data layer to
data layer and thus protect it from the transport layer.
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8. Evolution of XMPP-Grid
XMPP-Grid is the convergence of IF-MAP from the Trusted Computing
Group and the Platform-Exchange Grid (pxGrid) from Cisco Systems.
Both frameworks focus on enabling end users to implement multi-vendor
systems that share security context information that enables
coordinated defense-in-depth and security automation.
An ecosystem of vendors has been shipping IF-MAP enabled products
since 2008 to provide an architecture that supports standardized,
dynamic security data interexchange among a wide variety of
networking and security components. IF-MAP has been continually
enhanced by the Trusted Computing Group, culminating in the most
recent version, IF-MAP 2.2, published in March 2014. IF-MAP has
focused on providing a standardized information model that can be
utilized for data interoperability between vendors.
Cisco pxGrid was introduced in 2013 and has since developed a broad-
based security and networking vendor ecosystem. pxGrid was developed
by extending standards-based XMPP message routing. The goal of
pxGrid is to specifically address a lack of transport protocols
available in the industry that deliver highly scalable, many-to-many
platform security data interexchange in real-time.
XMPP-Grid brings together the strengths of both IF-MAP and pxGrid.
IF-MAP provides a mature and standardized information model. This
information model is accessible by Cisco pxGrid to transport relevant
data between systems. The combined XMPP-Grid delivers a highly
scalable, real-time data exchange transport protocol with an
interoperable information model based on the experience from real-
world, production deployments.
9. Acknowledgements
The authors would like to acknowledge the contributions, authoring
and/or editing of the following people: Henk Birkholz, Jessica
Fitzgerald-McKay, Steve Hanna, Steve Venema.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3922] Saint-Andre, P., "Mapping the Extensible Messaging and
Presence Protocol (XMPP) to Common Presence and Instant
Messaging (CPIM)", RFC 3922, October 2004.
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[RFC3923] Saint-Andre, P., "End-to-End Signing and Object Encryption
for the Extensible Messaging and Presence Protocol
(XMPP)", RFC 3923, October 2004.
[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and
Security Layer (SASL)", RFC 4422, June 2006.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, March 2011.
[RFC6121] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Instant Messaging and Presence", RFC
6121, March 2011.
10.2. Informative References
[I-D.ietf-sacm-terminology]
Waltermire, D., Montville, A., Harrington, D., Cam-Winget,
N., Lu, J., Ford, B., and M. Kaeo, "Terminology for
Security Assessment", draft-ietf-sacm-terminology-06 (work
in progress), February 2015.
[I-D.ietf-sacm-use-cases]
Waltermire, D. and D. Harrington, "Endpoint Security
Posture Assessment - Enterprise Use Cases", draft-ietf-
sacm-use-cases-09 (work in progress), March 2015.
[I-D.ietf-uta-tls-bcp]
Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of TLS and DTLS", draft-
ietf-uta-tls-bcp-11 (work in progress), February 2015.
[IF-MAP] Trusted Computing Group, "TNC Architecture for
Interoperability, Revision 1.5", May 2012.
[IF-MAP-ICS]
Trusted Computing Group, "TNC IF-MAP Metadata for ICS,
Security, Revision 1.0", October 2012.
[IF-MAP-NETSEC]
Trusted Computing Group, "TNC IF-MAP Metadata for Network
Security, Revision 1.0", August 2010.
[IF-MAP-SOAP]
Trusted Computing Group, "TNC IF-MAP Binding for SOAP,
Revision 2.1", May 2012.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
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[RFC5070] Danyliw, R., Meijer, J., and Y. Demchenko, "The Incident
Object Description Exchange Format", RFC 5070, December
2007.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
Authors' Addresses
Joseph Salowey
Tableau Software
837 North 34th Street, Suite 200
Seattle , WA 98103
Email: joe@salowey.net
Lisa Lorenzin
Pulse Secure
2700 Zanker Rd., Suite 200
San Jose, CA 95134
USA
Email: llorenzin@pulsesecure.net
Cliff Kahn
Pulse Secure
2700 Zanker Rd., Suite 200
San Jose, CA 95134
USA
Email: cliffordk@pulsesecure.net
Scott Pope
Cisco Systems
5400 Meadows Road
Suite 300
Lake Oswego, OR 97035
USA
Email: scottp@cisco.com
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Syam Appala
Cisco Systems
80 West Tasman Drive
San Jose, CA 95134
USA
Email: syam1@cisco.com
Aaron Woland
Cisco Systems
1900 South Boulevard
Charlotte, NC 28203
USA
Email: aawoland@cisco.com
Nancy Cam-Winget (editor)
Cisco Systems
3550 Cisco WAY
San Jose, CA 95134
USA
Email: ncamwing@cisco.com
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