Description A remotely exploitable crash vulnerability exists in the
SIP channel driver if an ACK with SDP is received after the
channel has been terminated. The handling code incorrectly
assumes that the channel will always be present.

Resolution A check has now been added which only parses SDP and applies
it if an Asterisk channel is present.

Note that Walter Doekes, OSSO B.V., is responsible for
diagnosing and providing the fix for this issue.

Affected Versions
Product Release Series
Asterisk Open Source 1.8.x 1.8.17.0 and above
Asterisk Open Source 11.x All versions
Certified Asterisk 1.8.15 All versions
Certified Asterisk 11.2 All versions

Corrected In
Product Release
Asterisk Open Source 1.8.23.1, 11.5.1
Certified Asterisk 1.8.15-cert3, 11.2-cert2

Patches
SVN URL Revision
http://downloads.asterisk.org/pub/security/AST-2013-004-1.8.diff Asterisk
1.8
http://downloads.asterisk.org/pub/security/AST-2013-004-11.diff Asterisk
11
http://downloads.asterisk.org/pub/security/AST-2013-004-1.8.15-cert.diff Certified
Asterisk
1.8.15
http://downloads.asterisk.org/pub/security/AST-2013-004-11.2-cert.diff Certified
Asterisk
11.1

Links https://issues.asterisk.org/jira/browse/ASTERISK-21064

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This document may be superseded by later versions; if so, the latest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-2013-004.pdf and
http://downloads.digium.com/pub/security/AST-2013-004.html

Revision History
Date Editor Revisions Made
2013-08-22 Joshua Colp Initial revision.

Asterisk Project Security Advisory - AST-2013-004
Copyright (c) 2013 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.