Asterisk Project Security Advisory – AST-2016-002

Product Asterisk
Summary File descriptor exhaustion in chan_sip
Nature of Advisory Denial of Service
Susceptibility Remote Unauthenticated Sessions
Severity Minor
Exploits Known Yes
Reported On September 17, 2015
Reported By Alexander Traud
Posted On February 3, 2016
Last Updated On February 3, 2016
Advisory Contact Richard Mudgett
CVE Name Pending

Description Setting the sip.conf timert1 value to a value higher than
1245 can cause an integer overflow and result in large
retransmit timeout times. These large timeout values hold
system file descriptors hostage and can cause the system to
run out of file descriptors.

Resolution Setting the sip.conf timert1 value to 1245 or lower will not
exhibit the vulnerability. The default timert1 value is 500.
Asterisk has been patched to detect the integer overflow and
calculate the previous retransmission timer value.

Affected Versions
Product Release
Series
Asterisk Open Source 1.8.x All versions
Asterisk Open Source 11.x All versions
Asterisk Open Source 12.x All versions
Asterisk Open Source 13.x All versions
Certified Asterisk 1.8.28 All versions
Certified Asterisk 11.6 All versions
Certified Asterisk 13.1 All versions

Corrected In
Product Release
Asterisk Open Source 11.21.1, 13.7.1
Certified Asterisk 11.6-cert12, 13.1-cert3

Patches
SVN URL Revision
http://downloads.asterisk.org/pub/security/AST-2016-002-1.8.28.diff Certified
Asterisk
1.8.28
http://downloads.asterisk.org/pub/security/AST-2016-002-11.6.diff Certified
Asterisk
11.6
http://downloads.asterisk.org/pub/security/AST-2016-002-13.1.diff Certified
Asterisk
13.1
http://downloads.asterisk.org/pub/security/AST-2016-002-1.8.diff Asterisk
1.8
http://downloads.asterisk.org/pub/security/AST-2016-002-11.diff Asterisk
11
http://downloads.asterisk.org/pub/security/AST-2016-002-12.diff Asterisk
12
http://downloads.asterisk.org/pub/security/AST-2016-002-13.diff Asterisk
13

Links https://issues.asterisk.org/jira/browse/ASTERISK-25397

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This document may be superseded by later versions; if so, the latest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-2016-002.pdf and
http://downloads.digium.com/pub/security/AST-2016-002.html

Revision History
Date Editor Revisions Made
September 29, 2015 Richard Mudgett Initial document created

Asterisk Project Security Advisory – AST-2016-002
Copyright (c) 2015 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.