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Asterisk Project Security Advisories are posted at http://www.asterisk.org/security This document may be superseded by later versions; if so, the latest version will be posted at http://downloads.digium.com/pub/security/AST-2012-006.pdf and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.