Asterisk Project Security Advisory - AST-2014-019 Product Asterisk Summary Remote Crash Vulnerability in WebSocket Server Nature of Advisory Denial of Service Susceptibility Remote Unauthenticated Sessions Severity Moderate Exploits Known No Reported On 30 October 2014 Reported By Badalian Vyacheslav Posted On 10 December 2014 Last Updated On December 10, 2014 Advisory Contact Joshua Colp <jcolp AT digium DOT com> CVE Name Description When handling a WebSocket frame the res_http_websocket module dynamically changes the size of the memory used to allow the provided payload to fit. If a payload length of zero was received the code would incorrectly attempt to resize to zero. This operation would succeed and end up freeing the memory but be treated as a failure. When the session was subsequently torn down this memory would get freed yet again causing a crash. Users of the WebSocket functionality also did not take into account that provided text frames are not guaranteed to be NULL terminated. This has been fixed in chan_sip and chan_pjsip in the applicable versions. Resolution Ensure the built-in HTTP server is disabled, upgrade to a version listed below, or apply the applicable patch. The change ensures that res_http_websocket does not treat the freeing of memory when a payload length of zero is received as fatal. Affected Versions Product Release Series Certified Asterisk 11.6 All versions Asterisk Open Source 11.x All versions Asterisk Open Source 12.x All versions Asterisk Open Source 13.x All versions Corrected In Product Release Certified Asterisk 11.6-cert9 Asterisk Open Source 11.14.2, 12.7.2, 13.0.2 Patches SVN URL Revision http://downloads.asterisk.org/pub/security/AST-2014-019-11.6.diff Certified Asterisk 11.6 http://downloads.asterisk.org/pub/security/AST-2014-019-11.diff Asterisk 11 http://downloads.asterisk.org/pub/security/AST-2014-019-12.diff Asterisk 12 http://downloads.asterisk.org/pub/security/AST-2014-019-13.diff Asterisk 13 Links https://issues.asterisk.org/jira/browse/ASTERISK-24472 Asterisk Project Security Advisories are posted at http://www.asterisk.org/security This document may be superseded by later versions; if so, the latest version will be posted at http://downloads.digium.com/pub/security/AST-2014-019.pdf and http://downloads.digium.com/pub/security/AST-2014-019.html Revision History Date Editor Revisions Made December 10 2014 Joshua Colp Initial Revision Asterisk Project Security Advisory - AST-2014-019 Copyright (c) 2014 Digium, Inc. All Rights Reserved. Permission is hereby granted to distribute and publish this advisory in its original, unaltered form.