idnits 2.17.1 draft-ietf-mile-xmpp-grid-03.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** There are 26 instances of too long lines in the document, the longest one being 25 characters in excess of 72. ** The abstract seems to contain references ([RFC7590]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (July 3, 2017) is 2488 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'I-D.ietf-mile-rolie' is defined on line 1006, but no explicit reference was found in the text == Unused Reference: 'RFC6546' is defined on line 1029, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. 'XEP-0030' -- Possible downref: Non-RFC (?) normative reference: ref. 'XEP-0060' -- Possible downref: Non-RFC (?) normative reference: ref. 'XEP-0268' == Outdated reference: A later version (-16) exists of draft-ietf-mile-rolie-07 -- Obsolete informational reference (is this intentional?): RFC 2818 (Obsoleted by RFC 9110) -- Obsolete informational reference (is this intentional?): RFC 5246 (Obsoleted by RFC 8446) Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 6 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MILE N. Cam-Winget, Ed. 3 Internet-Draft S. Appala 4 Intended status: Standards Track S. Pope 5 Expires: January 4, 2018 Cisco Systems 6 July 3, 2017 8 Using XMPP Protocol and its Extensions for Use with IODEF 9 draft-ietf-mile-xmpp-grid-03 11 Abstract 13 This document describes how the Extensible Messaging and Presence 14 Protocol (XMPP) [RFC7590] can be used as the framework as transport 15 protocol for collecting and distributing any security telemetry 16 information between any network connected device. As an example, 17 this document describes how XMPP can be used to transport the 18 Incident Object Description Exchange Format (IODEF) information. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on January 4, 2018. 37 Copyright Notice 39 Copyright (c) 2017 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 1.1. Glossary of Terms . . . . . . . . . . . . . . . . . . . . 3 56 1.2. Overview of XMPP-Grid . . . . . . . . . . . . . . . . . . 4 57 1.3. Benefits of XMPP-Grid . . . . . . . . . . . . . . . . . . 5 58 2. XMPP-Grid Architecture . . . . . . . . . . . . . . . . . . . 6 59 2.1. Using XMPP . . . . . . . . . . . . . . . . . . . . . . . 7 60 2.2. XMPP-Grid Requirements for enabling Information Sharing . 8 61 3. Example use of XMPP-Grid for IODEF . . . . . . . . . . . . . 9 62 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 63 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 64 5.1. Trust Model . . . . . . . . . . . . . . . . . . . . . . . 11 65 5.1.1. Network . . . . . . . . . . . . . . . . . . . . . . . 12 66 5.1.2. XMPP-Grid Nodes . . . . . . . . . . . . . . . . . . . 12 67 5.1.3. XMPP-Grid Controller . . . . . . . . . . . . . . . . 12 68 5.1.4. Certification Authority . . . . . . . . . . . . . . . 12 69 5.2. Threat Model . . . . . . . . . . . . . . . . . . . . . . 13 70 5.2.1. Network Attacks . . . . . . . . . . . . . . . . . . . 13 71 5.2.2. XMPP-Grid Nodes . . . . . . . . . . . . . . . . . . . 14 72 5.2.3. XMPP-Grid Controllers . . . . . . . . . . . . . . . . 15 73 5.2.4. Certification Authority . . . . . . . . . . . . . . . 16 74 5.3. Countermeasures . . . . . . . . . . . . . . . . . . . . . 17 75 5.3.1. Securing the XMPP-Grid Transport Protocol . . . . . . 17 76 5.3.2. Securing XMPP-Grid Nodes . . . . . . . . . . . . . . 18 77 5.3.3. Securing XMPP-Grid Controllers . . . . . . . . . . . 18 78 5.3.4. Limit on search result size . . . . . . . . . . . . . 19 79 5.3.5. Cryptographically random session-id and 80 authentication checks for ARC . . . . . . . . . . . . 19 81 5.3.6. Securing the Certification Authority . . . . . . . . 20 82 5.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . 20 83 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 21 84 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 85 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 86 8.1. Normative References . . . . . . . . . . . . . . . . . . 21 87 8.2. Informative References . . . . . . . . . . . . . . . . . 22 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 90 1. Introduction 92 XMPP-Grid is intended for use as a secure transport and 93 communications ecosystem for devices, applications and organizations 94 to interconnect, forming an information grid for the exchange of 95 formatted data (e.g. XML, JSON, etc). This document describes how 96 XMPP [RFC7590] serves as the framework and protocols for securely 97 collecting and distributing security telemetry information between 98 and among network platforms, endpoints, and most any network 99 connected device. 101 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 102 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 103 document are to be interpreted as described in [RFC2119]. 105 1.1. Glossary of Terms 107 Capability Provider 109 Providers who are capable of sharing information on XMPP-Grid. 111 Publisher 113 A capability provider sharing content information to other devices 114 participating on XMPP-Grid. 116 Subscriber 118 A device participating in XMPP-Grid and subscribing or consuming 119 information published by Publishers on XMPP-Grid. 121 Topics 123 Contextual information channel created on XMPP-Grid where a 124 published message by the Publisher will be propagated by XMPP in 125 real-time to a set of subscribed devices. 127 XMPP-Grid 129 Set of standards-based XMPP messages with extensions, intended for 130 use as a transport and communications protocol framework between 131 devices forming an information grid for sharing information. 133 XMPP-Grid Controller 135 Centralized component of XMPP-Grid responsible for managing all 136 control plane operations. 138 XMPP-Grid Node 140 Platform or device that implements XMPP to connect to XMPP-Grid 141 and share or consume security data. 143 1.2. Overview of XMPP-Grid 145 XMPP-Grid employs publish/subscribe/query operations brokered by a 146 controller, which enforces access control in the system. This XMPP- 147 based architecture controls what platforms can connect to the "Grid" 148 to share ("publish") and/or consume ("subscribe" or "query") 149 contextual information ("Topics") such as security data needed to 150 support MILE. 152 Leveraging the XMPP architecture, XMPP-Grid uses the XMPP server to 153 act as a controller, affecting the authentication and authorization 154 of participating XMPP-Grid nodes (Node). Security information may 155 only be published or consumed by authenticated and authorized Nodes 156 using the XMPP publish/subscribe extension defined in [XEP-0060]. 158 The components of XMPP-Grid are: 160 o XMPP-Grid Controller (Controller): The Controller manages the 161 control plane of XMPP-Grid operations. As such it authenticates 162 and authorizes platforms connecting to the data exchange grid and 163 controls whether or not they can publish, subscribe or query 164 Topics of security data. 166 o XMPP-Grid Node (Node): A Node is a platform or application that 167 has mutually authenticated with the Controller and obtained 168 authorization by the Controller to share and/or consume security 169 data. 171 o Data Repository: This is the source of security data available on 172 the Grid and may be a network security platform, management 173 console, endpoint, etc. XMPP-Grid does not mandate a specific 174 information model, but instead remains open to transport 175 structured or unstructured data. Data may be supplied by the 176 security platform itself or by an external information repository. 178 o Topic: An XMPP-Grid Topic defines a type of security data that a 179 platform wants to share with other platform(s) and a specified 180 interface by which the data can be obtained. 182 As enabled by the XMPP architecture, XMPP-Grid is used to exchange 183 security context data between systems on a 1-to-1, 1-to-many, or 184 many-to-many basis. Security data shared between these systems may 185 use pre-negotiated non-standard/native data formats or may utilize an 186 optional common information repository with a standardized data 187 format, such as IODEF. XMPP-Grid is data format agnostic and 188 accommodates transport of whatever format the end systems agree upon. 190 XMPP-Grid can operate in the following deployment architectures: 192 o Broker-Flow: An XMPP-Grid control plane brokers the authorization 193 and redirects the Topic subscriber to Topic publisher directly. 194 In this architecture, the Controller only manages the connection; 195 the security data flow is directly between Nodes using data 196 formats negotiated out-of-band. 198 o Centralized Data-Flow: An XMPP-Grid maintains the data within its 199 optional centralized database. In this architecture, the 200 Controller provides a common information structure for use in 201 formatting and storing security context data, such as IODEF, and 202 directly responds to Node publish and Subscribe requests. 204 o Proxy-Flow: An XMPP-Grid is acting as proxy, collecting the data 205 from the publisher(s) and presenting it to the subscriber 206 directly. This is used for ad-hoc queries. 208 Within the deployment architecture, XMPP-Grid may be used in any 209 combination of the following data exchange modes. The flexibility 210 afforded by the different modes enables security information to be 211 exchanged between systems in the method most suitable for serving a 212 given use-case. 214 o Continuous Topic update stream: This mode delivers in real-time 215 any data published to a Topic to the Nodes that are subscribed to 216 that Topic. 218 o Directed query: This mode enables Nodes to request a specific set 219 of security information regarding a specific asset, such as a 220 specific user endpoint. 222 o Bulk historic data query: This mode enables Nodes to request 223 transfer of past output from a Topic over a specific span of time. 225 1.3. Benefits of XMPP-Grid 227 Currently, security information standards such as IODEF [RFC7970] 228 defines a data models that has no explicit transport defined and 229 typically are carried over HTTPS as defined in RID [RFC6545]. 231 As security solutions are expanding to expose and share information 232 asynchronously and across network boundaries there is a need for an 233 architecture that facilitates federation, discovery of the different 234 information available, the interfaces used to obtain the information 235 and the need for near real-time exchange of data. 237 Based on XMPP, XMPP-Grid has been defined to meet those requirements. 239 2. XMPP-Grid Architecture 241 XMPP-Grid is an XMPP-based communication fabric that facilitates 242 secure sharing of information between network elements and networked 243 applications connected to the fabric both in real time and on demand 244 (see figure below). 246 +--------------------------------------+ 247 | +--------------------------------------+ 248 | | +--------------------------------------+ 249 | | | | 250 +-| | Node(s) | 251 +-| | 252 +--------------------------------------+ 253 / \ / \ / \ 254 / C \ / \ / \ 255 - o - - d - - - 256 ||n||A | a |B | |C 257 ||t|| | t | | | 258 - r - - a - | | 259 \ o / \ / | | 260 \ l / \ / | | 261 /|---------------------|\ | | 262 /|----/ \--------| d |--|\ 263 / / XMPP-Grid \ ctrl | a | \ 264 \ \ Controller / plane | t | / 265 \|----\ /--------| a |--|/ 266 \|---------------------|/ | | 267 / \ / \ | | 268 / C \ / \ | | 269 - o - - d - | | 270 ||n||A | a |B | |C 271 ||t|| | t | | | 272 - r - - a - - - 273 \ o / \ / \ / 274 \ l / \ / \ / 275 +------------------------------------+ 276 | |-+ 277 | Node(s) | | 278 | | |-+ 279 +------------------------------------+ | | 280 +------------------------------------+ | 281 +------------------------------------+ 283 Figure 1: XMPP-Grid Architecture 285 Nodes must connect to the XMPP-Grid controller to authenticate and 286 establish appropriate authorizations, with appropriate authorization 287 privileges. The control plane messaging is established through XMPP 288 and shown as "A" (Control plane interface) in Figure 1. Authorized 289 nodes may then share data either thru the XMPP-Grid Controller (shown 290 as "B" in Figure 1) or directly (shown as "C" in Figure 1). The data 291 messaging enable Nodes to: 293 o Receive real-time events of the published messages from the 294 publisher through Topic subscriptions 296 o Make directed queries to other Nodes in the XMPP-Grid with 297 appropriate authorization from the Controller 299 o Negotiate out-of-band secure file transfer channel with the peer 301 2.1. Using XMPP 303 XMPP is used as the foundation message routing protocol for 304 exchanging security data between systems across XMPP-Grid. XMPP is a 305 communications protocol for message-oriented middleware based on XML. 306 Designed to be extensible, the protocol uses de-centralized client- 307 server architecture where the clients connect to the servers securely 308 and the messages between the clients are routed through the XMPP 309 servers deployed within the cluster. XMPP has been used extensively 310 for publish-subscribe systems, file transfer, video, VoIP, Internet 311 of Things, Smart Grid Software Defined Networks (SDN) and other 312 collaboration and social networking applications. The following are 313 the 4 IETF specifications produced by the XMPP working group: 315 o [RFC7590] Extensible Messaging and Presence Protocol (XMPP): Core 317 o [RFC6121] Extensible Messaging and Presence Protocol (XMPP): 318 Instant Messaging and Presence 320 o [RFC3922] Mapping the Extensible Messaging and Presence Protocol 321 (XMPP) to Common Presence and Instant Messaging (CPIM) 323 o [RFC3923] End-to-End Signing and Object Encryption for the 324 Extensible Messaging and Presence Protocol (XMPP) 326 XMPP offers several of the following salient features for building a 327 security data interexchange protocol: 329 o Open - standards-based, decentralized and federated architecture, 330 with no single point of failure 332 o Security - Supports domain segregations and federation. Offers 333 strong security via Simple Authentication and Security Layer 334 (SASL) [RFC4422] and Transport Layer Security (TLS) [RFC5246]. 336 o Real-time event management/exchange - using publish, subscribe 337 notifications 339 o Flexibility and Extensibility - XMPP is XML based and is easily 340 extensible to adapt to new use-cases. Custom functionality can be 341 built on top of it. 343 o Multiple information exchanges - XMPP offers multiple information 344 exchange mechanisms between the participating clients - 346 o 348 * Real-time event notifications through publish and subscribe. 350 * On-demand or directed queries between the clients communicated 351 through the XMPP server 353 * Facilitates out-of-band, direct communication between 354 participating clients 356 o Bi-directional - avoids firewall tunneling and avoids opening up a 357 new connection in each direction between client and server. 359 o Scalable - supports cluster mode deployment with fan-out and 360 message routing 362 o Peer-to-peer communications also enables scale - directed queries 363 and out-of-band file transfer support 365 o XMPP offers Node availability, Node service capability discovery, 366 and Node presence within the XMPP network. Nodes ability to 367 detect the availability, presence and capabilities of other 368 participating nodes eases turnkey deployment. 370 The XMPP extensions used in XMPP-Grid are now part (e.g. publish/ 371 subscribe) of the main XMPP specification [RFC7590] and the presence 372 in [RFC6121]. A full list of XMPP Extension Protocols (XEPs) 373 [RFC7590] can be found in http://xmpp.org/extensions/xep-0001.html . 375 2.2. XMPP-Grid Requirements for enabling Information Sharing 377 This section summarizes the requirements and the extensions used to 378 facilitate the secure sharing of information using XMPP. Knowledge 379 of the XMPP Protocol and extensions is required to understand this 380 section. 382 o Authentication and Authorization: Nodes participating in XMPP-Grid 383 MUST mutually authenticate to the controller using XMPP's 384 authentication mechanisms. Authorization is affected by the 385 controller. 387 o Topic Discovery: to facilitate dynamic discovery, Nodes SHOULD 388 support the XMPP Service Discovery [XEP-0030]. 390 o Publish/Subscribe: to facilitate unsolicited notifications to new 391 or updated security information, Nodes MUST support the XMPP 392 Publish/Subscribe protocol as defined in [RFC7590]. 394 Once a Node has authenticated with the XMPP-Grid controller, it may 395 further register a topic (e.g. information type) to be shared or use 396 the discovery mechanism for determining topics to be consumed. 397 Sharing Information: security information may be shared using 398 registered topics. An example for sharing or consuming the IODEF 1.0 399 is defined in [XEP-0268]. 401 3. Example use of XMPP-Grid for IODEF 403 A Node follows the standard XMPP workflow for connecting to the 404 Controller as well as using the XMPP discovery mechanisms to discover 405 the availability to consume IODEF information. The general workflow 406 is summarized in the figure below: 408 |----------------| |----------------| |----------------| 409 | IODEF Client | | XMPP Server | | IODEF Service | 410 | (Subscriber) | | (Controller) | | (Publisher) | 411 |----------------| |----------------| |----------------| 412 | | | 413 | IODEF Client Authentication | | 414 |<---------------------------------->| | 415 | | IODEF Service Authentication | 416 | |<--------------------------------->| 417 | | Create IODEFas a Topic (XEP-0060) | 418 | |<----------------------------------| 419 | | Topic Creation Success | 420 | |---------------------------------->| 421 | Topic Discovery (XEP-0030) | | 422 |----------------------------------->| | 423 | Discovery Response with Topics | | 424 |<-----------------------------------| | 425 | | | 426 | Subscribe to IODEF Topic (XEP-0060)| | 427 |----------------------------------->| | 428 | Subscription Success | | 429 |<-----------------------------------| | 430 | | IODEF Incident Publish (XEP-0268) | 431 | IODEF Incident Publish |<----------------------------------| 432 |<-----------------------------------| | 433 | | | 435 Figure 2: IODEF Example XMPP Workflow 437 An example XMPP discovery request for an IODEF 1.0 topic is shown 438 below: 440 444 445 447 An example XMPP discovery response for an IODEF 1.0 topic is shown 448 below: 450 454 455 458 459 461 4. IANA Considerations 463 IODEF extensions as defined in [XEP-0268] may require IANA 464 considerations and assignment thru the IODEF IANA rules. 466 5. Security Considerations 468 An XMPP-Grid Controller serves as an controlling broker for XMPP-Grid 469 Nodes such as Enforcement Points, Policy Servers, CMDBs, and Sensors, 470 using a publish-subscribe-search model of information exchange and 471 lookup. By increasing the ability of XMPP-Grid Nodes to learn about 472 and respond to security-relevant events and data, XMPP-Grid can 473 improve the timeliness and utility of the security system. However, 474 this integrated security system can also be exploited by attackers if 475 they can compromise it. Therefore, strong security protections for 476 XMPP-Grid are essential. 478 This section provides a security analysis of the XMPP-Grid transport 479 protocol and the architectural elements that employ it, specifically 480 with respect to their use of this protocol. Three subsections define 481 the trust model (which elements are trusted to do what), the threat 482 model (attacks that may be mounted on the system), and the 483 countermeasures (ways to address or mitigate the threats previously 484 identified). 486 5.1. Trust Model 488 The first step in analyzing the security of the XMPP-Grid transport 489 protocol is to describe the trust model, listing what each 490 architectural element is trusted to do. The items listed here are 491 assumptions, but provisions are made in the Threat Model and 492 Countermeasures sections for elements that fail to perform as they 493 were trusted to do. 495 5.1.1. Network 497 The network used to carry XMPP-Grid messages is trusted to: 499 o Perform best effort delivery of network traffic 501 The network used to carry XMPP-Grid messages is not expected 502 (trusted) to: 504 o Provide confidentiality or integrity protection for messages sent 505 over it 507 o Provide timely or reliable service 509 5.1.2. XMPP-Grid Nodes 511 Authorized XMPP-Grid Nodes are trusted to: 513 o Preserve the confidentiality of sensitive data retrieved via the 514 XMPP-Grid Controller 516 5.1.3. XMPP-Grid Controller 518 The XMPP-Grid Controller is trusted to: 520 o Broker requests for data and enforce authorization of access to 521 this data throughout its lifecycle 523 o Perform service requests in a timely and accurate manner 525 o Create and maintain accurate operational attributes 527 o Only reveal data to and accept service requests from authorized 528 parties 530 The XMPP-Grid Controller is not expected (trusted) to: 532 o Verify the truth (correctness) of data 534 5.1.4. Certification Authority 536 The Certification Authority (CA) that issues certificates for the 537 XMPP-Grid Controller and/or XMPP-Grid Nodes (or each CA, if there are 538 several) is trusted to: 540 o Ensure that only proper certificates are issued and that all 541 certificates are issued in accordance with the CA's policies 543 o Revoke certificates previously issued when necessary 545 o Regularly and securely distribute certificate revocation 546 information 548 o Promptly detect and report any violations of this trust so that 549 they can be handled 551 The CA is not expected (trusted) to: 553 o Issue certificates that go beyond the XMPP-Grid needs or other 554 constraints imposed by a relying party. 556 5.2. Threat Model 558 To secure the XMPP-Grid transport protocol and the architectural 559 elements that implement it, this section identifies the attacks that 560 can be mounted against the protocol and elements. 562 5.2.1. Network Attacks 564 A variety of attacks can be mounted using the network. For the 565 purposes of this subsection the phrase "network traffic" should be 566 taken to mean messages and/or parts of messages. Any of these 567 attacks may be mounted by network elements, by parties who control 568 network elements, and (in many cases) by parties who control network- 569 attached devices. 571 o Network traffic may be passively monitored to glean information 572 from any unencrypted traffic 574 o Even if all traffic is encrypted, valuable information can be 575 gained by traffic analysis (volume, timing, source and destination 576 addresses, etc.) 578 o Network traffic may be modified in transit 580 o Previously transmitted network traffic may be replayed 582 o New network traffic may be added 584 o Network traffic may be blocked, perhaps selectively 586 o A "Man In The Middle" (MITM) attack may be mounted where an 587 attacker interposes itself between two communicating parties and 588 poses as the other end to either party or impersonates the other 589 end to either or both parties 591 o Resist attacks (including denial of service and other attacks from 592 XMPP-Grid Nodes) 594 o Undesired network traffic may be sent in an effort to overload an 595 architectural component, thus mounting a denial of service attack 597 5.2.2. XMPP-Grid Nodes 599 An unauthorized XMPP-Grid Nodes (one which is not recognized by the 600 XMPP-Grid Controller or is recognized but not authorized to perform 601 any actions) cannot mount any attacks other than those listed in the 602 Network Attacks section above. 604 An authorized XMPP-Grid Node, on the other hand, can mount many 605 attacks. These attacks might occur because the XMPP-Grid Node is 606 controlled by a malicious, careless, or incompetent party (whether 607 because its owner is malicious, careless, or incompetent or because 608 the XMPP-Grid Node has been compromised and is now controlled by a 609 party other than its owner). They might also occur because the XMPP- 610 Grid Node is running malicious software; because the XMPP-Grid Node 611 is running buggy software (which may fail in a state that floods the 612 network with traffic); or because the XMPP-Grid Node has been 613 configured improperly. From a security standpoint, it generally 614 makes no difference why an attack is initiated. The same 615 countermeasures can be employed in any case. 617 Here is a list of attacks that may be mounted by an authorized XMPP- 618 Grid Node: 620 o Cause many false alarms or otherwise overload the XMPP-Grid 621 Controller or other elements in the network security system 622 (including human administrators) leading to a denial of service or 623 disabling parts of the network security system 625 o Omit important actions (such as posting incriminating data), 626 resulting in incorrect access 628 o Use confidential information obtained from the XMPP-Grid 629 Controller to enable further attacks (such as using endpoint 630 health check results to exploit vulnerable endpoints) 632 o Advertise data crafted to exploit vulnerabilities in the XMPP-Grid 633 Controller or in other XMPP-Grid Nodes, with a goal of 634 compromising those systems 636 o Issue a search request or set up a subscription that matches an 637 enormous result, leading to resource exhaustion on the XMPP-Grid 638 Controller, the publishing XMPP-Grid Node, and/or the network 640 o Establish a communication channel using another XMPP-Grid Node's 641 session-id 643 Dependencies of or vulnerabilities of authorized XMPP-Grid Nodes may 644 be exploited to effect these attacks. Another way to effect these 645 attacks is to gain the ability to impersonate an XMPP-Grid Node 646 (through theft of the XMPP-Grid Node's identity credentials or 647 through other means). Even a clock skew between the XMPP-Grid Node 648 and XMPP-Grid Controller can cause problems if the XMPP-Grid Node 649 assumes that old XMPP-Grid Node data should be ignored. 651 5.2.3. XMPP-Grid Controllers 653 An unauthorized XMPP-Grid Controller (one which is not trusted by 654 XMPP-Grid Nodes) cannot mount any attacks other than those listed in 655 the Network Attacks section above. 657 An authorized XMPP-Grid Controller can mount many attacks. Similar 658 to the XMPP-Grid Node case described above, these attacks might occur 659 because the XMPP-Grid Controller is controlled by a malicious, 660 careless, or incompetent party (either an XMPP-Grid Controller 661 administrator or an attacker who has seized control of the XMPP-Grid 662 Controller). They might also occur because the XMPP-Grid Controller 663 is running malicious software, because the XMPP-Grid Controller is 664 running buggy software (which may fail in a state that corrupts data 665 or floods the network with traffic), or because the XMPP-Grid 666 Controller has been configured improperly. 668 All of the attacks listed for XMPP-Grid Node above can be mounted by 669 the XMPP-Grid Controller. Detection of these attacks will be more 670 difficult since the XMPP-Grid Controller can create false operational 671 attributes and/or logs that imply some other party created any bad 672 data. 674 Additional XMPP-Grid Controller attacks may include: 676 o Expose different data to different XMPP-Grid Nodes to mislead 677 investigators or cause inconsistent behavior 679 o Mount an even more effective denial of service attack than a 680 single XMPP-Grid Node could 682 o Obtain and cache XMPP-Grid Node credentials so they can be used to 683 impersonate XMPP-Grid Nodes even after a breach of the XMPP-Grid 684 Controller is repaired 686 o Obtain and cache XMPP-Grid Controller administrator credentials so 687 they can be used to regain control of the XMPP-Grid Controller 688 after the breach of the XMPP-Grid Controller is repaired 690 Dependencies of or vulnerabilities of the XMPP-Grid Controller may be 691 exploited to obtain control of the XMPP-Grid Controller and effect 692 these attacks. 694 5.2.4. Certification Authority 696 A Certification Authority trusted to issue certificates for the XMPP- 697 Grid Controller and/or XMPP-Grid Nodes can mount several attacks: 699 o Issue certificates for unauthorized parties, enabling them to 700 impersonate authorized parties such as the XMPP-Grid Controller or 701 an XMPP-Grid Node. This can lead to all the threats that can be 702 mounted by the certificate's subject. 704 o Issue certificates without following all of the CA's policies. 705 Because this can result in issuing certificates that may be used 706 to impersonate authorized parties, this can lead to all the 707 threats that can be mounted by the certificate's subject. 709 o Fail to revoke previously issued certificates that need to be 710 revoked. This can lead to undetected impersonation of the 711 certificate's subject or failure to revoke authorization of the 712 subject, and therefore can lead to all of the threats that can be 713 mounted by that subject. 715 o Fail to regularly and securely distribute certificate revocation 716 information. This may cause a relying party to accept a revoked 717 certificate, leading to undetected impersonation of the 718 certificate's subject or failure to revoke authorization of the 719 subject, and therefore can lead to all of the threats that can be 720 mounted by that subject. It can also cause a relying party to 721 refuse to proceed with a transaction because timely revocation 722 information is not available, even though the transaction should 723 be permitted to proceed. 725 o Allow the CA's private key to be revealed to an unauthorized 726 party. This can lead to all the threats above. Even worse, the 727 actions taken with the private key will not be known to the CA. 729 o Fail to promptly detect and report errors and violations of trust 730 so that relying parties can be promptly notified. This can cause 731 the threats listed earlier in this section to persist longer than 732 necessary, leading to many knock-on effects. 734 5.3. Countermeasures 736 Below are countermeasures for specific attack scenarios to the XMPP- 737 Grid infrastructure. 739 5.3.1. Securing the XMPP-Grid Transport Protocol 741 To address network attacks, the XMPP-Grid transport protocol 742 described in this document requires that the XMPP-Grid messages MUST 743 be carried over TLS (minimally TLS 1.2 [RFC5246]) as described in 744 [RFC2818]. The XMPP-Grid Node MUST verify the XMPP-Grid Controller's 745 certificate and determine whether the XMPP-Grid Controller is trusted 746 by this XMPP-Grid Node before completing the TLS handshake. The 747 XMPP-Grid Controller MUST authenticate the XMPP-Grid Node either 748 using mutual certificate-based authentication in the TLS handshake or 749 using Basic Authentication as described in IETF RFC 2617. XMPP-Grid 750 Controller MUST use Simple Authentication and Security Layer (SASL), 751 described in [RFC4422], to support the aforesaid authentication 752 mechanisms. SASL offers authentication mechanism negotiations 753 between the XMPP-Grid Controller and XMPP-Grid node during the 754 connection establishment phase. XMPP-Grid Nodes and XMPP-Grid 755 Controllers using mutual certificate-based authentication SHOULD each 756 verify the revocation status of the other party's certificate. All 757 XMPP-Grid Controllers and XMPP-Grid Nodes MUST implement both mutual 758 certificate-based authentication and Basic Authentication. The 759 selection of which XMPP-Grid Node authentication technique to use in 760 any particular deployment is left to the administrator. 762 An XMPP-Grid Controller MAY also support a local, configurable set of 763 Basic Authentication userid-password pairs. If so, it is 764 implementation dependent whether an XMPP-Grid Controller ends a 765 session when an administrator changes the configured password. Since 766 Basic Authentication has many security disadvantages (especially the 767 transmission of reusable XMPP-Grid Node passwords to the XMPP-Grid 768 Controller), it SHOULD only be used when absolutely necessary. Per 769 the HTTP specification, when basic authentication is in use, an XMPP- 770 Grid Controller MAY respond to any request that lacks credentials 771 with an error code similar to HTTP code 401. An XMPP-Grid Node 772 SHOULD avoid this code by submitting basic auth credentials with 773 every request when basic authentication is in use. If it does not do 774 so, an XMPP-Grid Node MUST respond to this code by resubmitting the 775 same request with credentials (unless the XMPP-Grid Node is shutting 776 down). 778 As XMPP uses TLS as the transport and security mechanisms, it is 779 understood that best practices such as those in 780 [I-D.ietf-uta-tls-bcp] are followed. 782 These protocol security measures provide protection against all the 783 network attacks listed in the above document section except denial of 784 service attacks. If protection against these denial of service 785 attacks is desired, ingress filtering, rate limiting per source IP 786 address, and other denial of service mitigation measures may be 787 employed. In addition, an XMPP-Grid Controller MAY automatically 788 disable a misbehaving XMPP-Grid Node. 790 5.3.2. Securing XMPP-Grid Nodes 792 XMPP-Grid Nodes may be deployed in locations that are susceptible to 793 physical attacks. Physical security measures may be taken to avoid 794 compromise of XMPP-Grid Nodes, but these may not always be practical 795 or completely effective. An alternative measure is to configure the 796 XMPP-Grid Controller to provide read-only access for such systems. 797 The XMPP-Grid Controller SHOULD also include a full authorization 798 model so that individual XMPP-Grid Nodes may be configured to have 799 only the privileges that they need. The XMPP-Grid Controller MAY 800 provide functional templates so that the administrator can configure 801 a specific XMPP-Grid Node as a DHCP server and authorize only the 802 operations and metadata types needed by a DHCP server to be permitted 803 for that XMPP-Grid Node. These techniques can reduce the negative 804 impacts of a compromised XMPP-Grid Node without diminishing the 805 utility of the overall system. 807 To handle attacks within the bounds of this authorization model, the 808 XMPP-Grid Controller MAY also include rate limits and alerts for 809 unusual XMPP-Grid Node behavior. XMPP-Grid Controllers SHOULD make 810 it easy to revoke an XMPP-Grid Node's authorization when necessary. 811 Another way to detect attacks from XMPP-Grid Nodes is to create fake 812 entries in the available data (honeytokens) which normal XMPP-Grid 813 Nodes will not attempt to access. The XMPP-Grid Controller SHOULD 814 include auditable logs of XMPP-Grid Node activities. 816 To avoid compromise of XMPP-Grid Node, XMPP-Grid Node SHOULD be 817 hardened against attack and minimized to reduce their attack surface. 818 They should be well managed to minimize vulnerabilities in the 819 underlying platform and in systems upon which the XMPP-Grid Node 820 depends. Personnel with administrative access should be carefully 821 screened and monitored to detect problems as soon as possible. 823 5.3.3. Securing XMPP-Grid Controllers 825 Because of the serious consequences of XMPP-Grid Controller 826 compromise, XMPP-Grid Controllers SHOULD be especially well hardened 827 against attack and minimized to reduce their attack surface. They 828 should be well managed to minimize vulnerabilities in the underlying 829 platform and in systems upon which the XMPP-Grid Controller depends. 831 Network security measures such as firewalls or intrusion detection 832 systems may be used to monitor and limit traffic to and from the 833 XMPP-Grid Controller. Personnel with administrative access should be 834 carefully screened and monitored to detect problems as soon as 835 possible. Administrators should not use password-based 836 authentication but should instead use non-reusable credentials and 837 multi-factor authentication (where available). Physical security 838 measures SHOULD be employed to prevent physical attacks on XMPP-Grid 839 Controllers. 841 To ease detection of XMPP-Grid Controller compromise should it occur, 842 XMPP-Grid Controller behavior should be monitored to detect unusual 843 behavior (such as a reboot, a large increase in traffic, or different 844 views of an information repository for similar XMPP-Grid Nodes). 845 XMPP-Grid Nodes should log and/or notify administrators when peculiar 846 XMPP-Grid Controller behavior is detected. To aid forensic 847 investigation, permanent read-only audit logs of security-relevant 848 information (especially administrative actions) should be maintained. 849 If XMPP-Grid Controller compromise is detected, a careful analysis 850 should be performed of the impact of this compromise. Any reusable 851 credentials that may have been compromised should be reissued. 853 5.3.4. Limit on search result size 855 While XMPP-Grid is designed for high scalability to 100,000s of 856 Nodes, an XMPP-Grid Controller MAY establish a limit to the amount of 857 data it is willing to return in search or subscription results. This 858 mitigates the threat of an XMPP-Grid Node causing resource exhaustion 859 by issuing a search or subscription that leads to an enormous result. 861 5.3.5. Cryptographically random session-id and authentication checks 862 for ARC 864 An XMPP-Grid Controller SHOULD ensure that the XMPP-Grid Node 865 establishing an Authenticated Results Chain (ARC) is the same XMPP- 866 Grid Node as the XMPP-Grid Node that established the corresponding 867 Synchronization Source Identifier (SSRC). The XMPP-Grid Controller 868 SHOULD employ both of the following strategies: 870 o session-ids SHOULD be cryptographically random 872 o The HTTPS transport for the SSRC and the ARC SHOULD be 873 authenticated using the same credentials. SSL session resumption 874 MAY be used to establish the ARC based on the SSRC SSL session. 876 5.3.6. Securing the Certification Authority 878 As noted above, compromise of a Certification Authority (CA) trusted 879 to issue certificates for the XMPP-Grid Controller and/or XMPP-Grid 880 Nodes is a major security breach. Many guidelines for proper CA 881 security have been developed: the CA/Browser Forum's Baseline 882 Requirements, the AICPA/CICA Trust Service Principles, etc. The CA 883 operator and relying parties should agree on an appropriately 884 rigorous security practices to be used. 886 Even with the most rigorous security practices, a CA may be 887 compromised. If this compromise is detected quickly, relying parties 888 can remove the CA from their list of trusted CAs, and other CAs can 889 revoke any certificates issued to the CA. However, CA compromise may 890 go undetected for some time, and there's always the possibility that 891 a CA is being operated improperly or in a manner that is not in the 892 interests of the relying parties. For this reason, relying parties 893 may wish to "pin" a small number of particularly critical 894 certificates (such as the certificate for the XMPP-Grid Controller). 895 Once a certificate has been pinned, the relying party will not accept 896 another certificate in its place unless the Administrator explicitly 897 commands it to do so. This does not mean that the relying party will 898 not check the revocation status of pinned certificates. However, the 899 Administrator may still be consulted if a pinned certificate is 900 revoked, since the CA and revocation process are not completely 901 trusted. 903 5.4. Summary 905 XMPP-Grid's considerable value as a broker for security-sensitive 906 data exchange distribution also makes the protocol and the network 907 security elements that implement it a target for attack. Therefore, 908 strong security has been included as a basic design principle within 909 the XMPP-Grid design process. 911 The XMPP-Grid transport protocol provides strong protection against a 912 variety of different attacks. In the event that an XMPP-Grid Node or 913 XMPP-Grid Controller is compromised, the effects of this compromise 914 have been reduced and limited with the recommended role-based 915 authorization model and other provisions, and best practices for 916 managing and protecting XMPP-Grid systems have been described. Taken 917 together, these measures should provide protection commensurate with 918 the threat to XMPP-Grid systems, thus ensuring that they fulfill 919 their promise as a network security clearing-house. 921 6. Privacy Considerations 923 XMPP-Grid Nodes may publish information about endpoint health, 924 network access, events (which may include information about what 925 services an endpoint is accessing), roles and capabilities, and the 926 identity of the end user operating the endpoint. Any of this 927 published information may be queried by other XMPP-Grid Nodes and 928 could potentially be used to correlate network activity to a 929 particular end user. 931 Dynamic and static information brokered by an XMPP-Grid Controller, 932 ostensibly for purposes of correlation by XMPP-Grid Nodes for 933 intrusion detection, could be misused by a broader set of XMPP-Grid 934 Nodes which hitherto have been performing specific roles with strict 935 well-defined separation of duties. 937 Care should be taken by deployers of XMPP-Grid to ensure that the 938 information published by XMPP-Grid Nodes does not violate agreements 939 with end users or local and regional laws and regulations. This can 940 be accomplished either by configuring XMPP-Grid Nodes to not publish 941 certain information or by restricting access to sensitive data to 942 trusted XMPP-Grid Nodes. That is, the easiest means to ensure 943 privacy or protect sensitive data, is to omit or not share it at all. 945 Another consideration for deployers is to enable end-to-end 946 encryption to ensure the data is protected from the data layer to 947 data layer and thus protect it from the transport layer. 949 7. Acknowledgements 951 The authors would like to acknowledge the contributions, authoring 952 and/or editing of the following people: Joseph Salowey, Lisa 953 Lorenzin, Clifford Kahn, Henk Birkholz, Jessica Fitzgerald-McKay, 954 Steve Hanna, and Steve Venema. In addition, we want to thank Takeshi 955 Takahashi, Panos Kampanakis, Adam Montville and Chris Inacio for 956 reviewing and providing valuable comments. 958 8. References 960 8.1. Normative References 962 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 963 Requirement Levels", BCP 14, RFC 2119, 964 DOI 10.17487/RFC2119, March 1997, 965 . 967 [RFC3922] Saint-Andre, P., "Mapping the Extensible Messaging and 968 Presence Protocol (XMPP) to Common Presence and Instant 969 Messaging (CPIM)", RFC 3922, DOI 10.17487/RFC3922, October 970 2004, . 972 [RFC3923] Saint-Andre, P., "End-to-End Signing and Object Encryption 973 for the Extensible Messaging and Presence Protocol 974 (XMPP)", RFC 3923, DOI 10.17487/RFC3923, October 2004, 975 . 977 [RFC4422] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 978 Authentication and Security Layer (SASL)", RFC 4422, 979 DOI 10.17487/RFC4422, June 2006, 980 . 982 [RFC6121] Saint-Andre, P., "Extensible Messaging and Presence 983 Protocol (XMPP): Instant Messaging and Presence", 984 RFC 6121, DOI 10.17487/RFC6121, March 2011, 985 . 987 [RFC7590] Saint-Andre, P. and T. Alkemade, "Use of Transport Layer 988 Security (TLS) in the Extensible Messaging and Presence 989 Protocol (XMPP)", RFC 7590, DOI 10.17487/RFC7590, June 990 2015, . 992 [XEP-0030] 993 Hildebrand, J., Millard, P., Eatmon, R., and P. Saint- 994 Andre, "Service Discovery", XSF XEP 0030, July 2010. 996 [XEP-0060] 997 Millard, P. and P. Saint-Andre, "Publish-Subscribe", 998 XSF XEP 0060, December 2016. 1000 [XEP-0268] 1001 Hefczyc, A., Jensen, F., Remond, M., Saint-Andre, P., and 1002 M. Wild, "Service Discovery", XSF XEP 0268, MY 2012. 1004 8.2. Informative References 1006 [I-D.ietf-mile-rolie] 1007 Field, J., Banghart, S., and D. Waltermire, "Resource- 1008 Oriented Lightweight Information Exchange", draft-ietf- 1009 mile-rolie-07 (work in progress), May 2017. 1011 [I-D.ietf-uta-tls-bcp] 1012 Sheffer, Y., Holz, R., and P. Saint-Andre, 1013 "Recommendations for Secure Use of TLS and DTLS", draft- 1014 ietf-uta-tls-bcp-11 (work in progress), February 2015. 1016 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 1017 DOI 10.17487/RFC2818, May 2000, 1018 . 1020 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 1021 (TLS) Protocol Version 1.2", RFC 5246, 1022 DOI 10.17487/RFC5246, August 2008, 1023 . 1025 [RFC6545] Moriarty, K., "Real-time Inter-network Defense (RID)", 1026 RFC 6545, DOI 10.17487/RFC6545, April 2012, 1027 . 1029 [RFC6546] Trammell, B., "Transport of Real-time Inter-network 1030 Defense (RID) Messages over HTTP/TLS", RFC 6546, 1031 DOI 10.17487/RFC6546, April 2012, 1032 . 1034 [RFC7970] Danyliw, R., "The Incident Object Description Exchange 1035 Format Version 2", RFC 7970, DOI 10.17487/RFC7970, 1036 November 2016, . 1038 Authors' Addresses 1040 Nancy Cam-Winget (editor) 1041 Cisco Systems 1042 3550 Cisco Way 1043 San Jose, CA 95134 1044 USA 1046 Email: ncamwing@cisco.com 1048 Syam Appala 1049 Cisco Systems 1050 3550 Cisco Way 1051 San Jose, CA 95134 1052 USA 1054 Email: syam1@cisco.com 1055 Scott Pope 1056 Cisco Systems 1057 5400 Meadows Road 1058 Suite 300 1059 Lake Oswego, OR 97035 1060 USA 1062 Email: scottp@cisco.com