AST-2012-006: Remote Crash Vulnerability in SIP Channel Driver



Asterisk Project Security Advisory - AST-2012-006

Product Asterisk
Summary Remote Crash Vulnerability in SIP Channel Driver
Nature of Advisory Remote Crash
Susceptibility Remote Authenticated Sessions
Severity Moderate
Exploits Known No
Reported On April 16, 2012
Reported By Thomas Arimont
Posted On April 23, 2012
Last Updated On April 23, 2012
Advisory Contact Matt Jordan < mjordan AT digium DOT com >
CVE Name

Description A remotely exploitable crash vulnerability exists in the
SIP channel driver if a SIP UPDATE request is processed
within a particular window of time. For this to occur, the
following must take place:

1. The setting 'trustrpid' must be set to True

2. An UPDATE request must be received after a call has been
terminated and the associated channel object has been
destroyed, but before the SIP dialog associated with the
call has been destroyed. Receiving the UPDATE request
before the call is terminated or after the SIP dialog
associated with the call will not cause the crash
vulnerability described here.

3. The UPDATE request must be formatted with the
appropriate headers to reflect an Asterisk connected line
update. The information in the headers must reflect a
different Caller ID then what was previously associated
with the dialog.

When these conditions are true, Asterisk will attempt to
perform a connected line update with no associated channel,
and will crash.

Resolution Asterisk now ensures a channel exists before performing a
connected line update, when that connected line update is
initiated via a SIP UPDATE request.

In Asterisk versions not containing the fix for this issue,
setting the 'trustrpid' setting to False will prevent this
crash from occurring (default is False)

Affected Versions
Product Release Series
Asterisk Open Source 1.8.x All versions
Asterisk Open Source 10.x All versions
Asterisk Business Edition C.3.x All versions

Corrected In
Product Release
Asterisk Open Source 1.8.11.1, 10.3.1
Asterisk Business Edition C.3.7.4

Patches
SVN URL Revision
http://downloads.asterisk.org/pub/security/AST-2012-006-1.8.diff v1.8
http://downloads.asterisk.org/pub/security/AST-2012-006-10.diff v.10

Links https://issues.asterisk.org/jira/browse/ASTERISK-19770

Asterisk Project Security Advisories are posted at
http://www.asterisk.org/security

This document may be superseded by later versions; if so, the latest
version will be posted at
http://downloads.digium.com/pub/security/AST-2012-006.pdf and
http://downloads.digium.com/pub/security/AST-2012-006.html

Revision History
Date Editor Revisions Made
04/16/2012 Matt Jordan Initial release.

Asterisk Project Security Advisory - AST-2012-006
Copyright (c) 2012 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.