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
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This document may be superseded by later versions; if so, the latest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.