Addressing an Amplification Vulnerability in Session Initiation Protocol (SIP) Forking Proxies
RFC 5393
| Document | Type |
RFC - Proposed Standard
(December 2008; No errata)
Updates RFC 3261
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5393 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Cullen Jennings | ||
| Send notices to | (None) | ||
Network Working Group R. Sparks, Ed.
Request for Comments: 5393 Tekelec
Updates: 3261 S. Lawrence
Category: Standards Track Nortel Networks, Inc.
A. Hawrylyshen
Ditech Networks Inc.
B. Campen
Tekelec
December 2008
Addressing an Amplification Vulnerability
in Session Initiation Protocol (SIP) Forking Proxies
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (c) 2008 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (http://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Abstract
This document normatively updates RFC 3261, the Session Initiation
Protocol (SIP), to address a security vulnerability identified in SIP
proxy behavior. This vulnerability enables an attack against SIP
networks where a small number of legitimate, even authorized, SIP
requests can stimulate massive amounts of proxy-to-proxy traffic.
This document strengthens loop-detection requirements on SIP proxies
when they fork requests (that is, forward a request to more than one
destination). It also corrects and clarifies the description of the
loop-detection algorithm such proxies are required to implement.
Additionally, this document defines a Max-Breadth mechanism for
limiting the number of concurrent branches pursued for any given
request.
Sparks, et al. Standards Track [Page 1]
RFC 5393 Amplification Vulnerability in SIP December 2008
Table of Contents
1. Introduction ....................................................3
2. Conventions and Definitions .....................................3
3. Vulnerability: Leveraging Forking to Flood a Network ............3
4. Updates to RFC 3261 .............................................7
4.1. Strengthening the Requirement to Perform Loop Detection ....7
4.2. Correcting and Clarifying the RFC 3261
Loop-Detection Algorithm ...................................7
4.2.1. Update to Section 16.6 ..............................7
4.2.2. Update to Section 16.3 ..............................8
4.2.3. Impact of Loop Detection on Overall Network
Performance .........................................9
4.2.4. Note to Implementers ................................9
5. Max-Breadth ....................................................10
5.1. Overview ..................................................10
5.2. Examples ..................................................11
5.3. Formal Mechanism ..........................................12
5.3.1. Max-Breadth Header Field ...........................12
5.3.2. Terminology ........................................13
5.3.3. Proxy Behavior .....................................13
5.3.3.1. Reusing Max-Breadth .......................14
5.3.4. UAC Behavior .......................................14
5.3.5. UAS Behavior .......................................14
5.4. Implementer Notes .........................................14
5.4.1. Treatment of CANCEL ................................14
5.4.2. Reclamation of Max-Breadth on 2xx Responses ........14
5.4.3. Max-Breadth and Automaton UAs ......................14
5.5. Parallel and Sequential Forking ...........................15
5.6. Max-Breadth Split Weight Selection ........................15
5.7. Max-Breadth's Effect on Forking-Based
Amplification Attacks .....................................15
5.8. Max-Breadth Header Field ABNF Definition ..................16
6. IANA Considerations ............................................16
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