AST-2012-014: Crashes due to large stack allocations when using TCP Jan 02 2013 09:23PM
Asterisk Security Team (security asterisk org)
Asterisk Project Security Advisory - AST-2012-014

Product Asterisk
Summary Crashes due to large stack allocations when using
Nature of Advisory Stack Overflow
Susceptibility Remote Unauthenticated Sessions (SIP)

Remote Authenticated Sessions (XMPP, HTTP)
Severity Critical
Exploits Known No
Reported On 7 November, 2012
Reported By Walter Doekes
Posted On 2 January, 2013
Last Updated On January 2, 2013
Advisory Contact Mark Michelson <mmichelson AT digium DOT com>
CVE Name CVE-2012-5976

Description Asterisk has several places where messages received over
various network transports may be copied in a single stack
allocation. In the case of TCP, since multiple packets in a
stream may be concatenated together, this can lead to large
allocations that overflow the stack.

In the case of SIP, it is possible to do this before a
session is established. Keep in mind that SIP over UDP is
not affected by this vulnerability.

With HTTP and XMPP, a session must first be established
before the vulnerability may be exploited. The XMPP
vulnerability exists both in the res_jabber.so module in
Asterisk 1.8, 10, and 11 as well as the res_xmpp.so module
in Asterisk 11.

Resolution Stack allocations when using TCP have either been eliminated
in favor of heap allocations or have had an upper bound
placed on them to ensure that the stack will not overflow.

For SIP, the allocation now has an upper limit.

For HTTP, the allocation is now a heap allocation instead of
a stack allocation.

For XMPP, the allocation has been eliminated since it was

Affected Versions
Product Release Series
Asterisk Open Source 1.8.x All versions
Asterisk Open Source 10.x All versions
Asterisk Open Source 11.x All versions
Certified Asterisk 1.8.11 SIP: unaffected

HTTP and XMPP: All versions
Asterisk Digiumphones 10.x-digiumphones All versions

Corrected In
Product Release
Asterisk Open Source, 10.11.1, 11.1.1
Certified Asterisk 1.8.11-cert10
Asterisk Digiumphones 10.11.1-digiumphones

SVN URL Revision
http://downloads.asterisk.org/pub/security/AST-2012-014-1.8.diff Asterisk
http://downloads.asterisk.org/pub/security/AST-2012-014-10.diff Asterisk
http://downloads.asterisk.org/pub/security/AST-2012-014-11.diff Asterisk

Links https://issues.asterisk.org/jira/browse/ASTERISK-20658

Asterisk Project Security Advisories are posted at

This document may be superseded by later versions; if so, the latest
version will be posted at
http://downloads.digium.com/pub/security/AST-2012-014.pdf and

Revision History
Date Editor Revisions Made
19 November, 2012 Mark Michelson Initial Draft
02 January, 2013 Matt Jordan Removed ABE from affected products

Asterisk Project Security Advisory - AST-2012-014
Copyright (c) 2012 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.

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