Asterisk Security Team
2019-Sep-05 14:49 UTC
[asterisk-users] AST-2019-005: Remote Crash Vulnerability in audio transcoding
Asterisk Project Security Advisory - AST-2019-005
Product Asterisk
Summary Remote Crash Vulnerability in audio transcoding
Nature of Advisory Denial of Service
Susceptibility Remote Unauthenticated Sessions
Severity Minor
Exploits Known No
Reported On August 7, 2019
Reported By Gregory Massel
Posted On
Last Updated On August 26, 2019
Advisory Contact Jcolp AT sangoma DOT com
CVE Name CVE-2019-15639
Description When audio frames are given to the audio transcoding
support in Asterisk the number of samples are examined
and as part of this a message is output to indicate
that no samples are present. A change was done to
suppress this message for a particular scenario in
which the message was not relevant. This change
assumed that information about the origin of a frame
will always exist when in reality it may not.
This issue presented itself when an RTP packet
containing no audio (and thus no samples) was
received. In a particular transcoding scenario this
audio frame would get turned into a frame with no
origin information. If this new frame was then given
to the audio transcoding support a crash would occur
as no samples and no origin information would be
present. The transcoding scenario requires the
“genericplc” option to be set to enabled (the default)
and a transcoding path from the source format into
signed linear and then from signed linear into another
format.
Note that there may be other scenarios that have not
been found which can cause an audio frame with no
origin to be given to the audio transcoding support
and thus cause a crash.
Modules Affected main/translate.c
Resolution The “genericplc” option can be disabled in codecs.conf to
mitigate the described scenario. It is recommended, however,
that Asterisk be upgraded to one of the listed versions or
the linked patch applied to protect against potential
unknown scenarios.
Affected Versions
Product Release Series
Asterisk Open Source 13.x 13.28.0
Asterisk Open Source 16.x 16.5.0
Corrected In
Product Release
Asterisk Open Source 13.28.1
Asterisk Open Source 16.5.1
Patches
SVN URL Revision
http://downloads.asterisk.org/pub/security/AST-2019-005-13.diff Asterisk
13
http://downloads.asterisk.org/pub/security/AST-2019-005-16.diff Asterisk
16
Links https://issues.asterisk.org/jira/browse/ASTERISK-28499
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-2019-005.pdf and
http://downloads.digium.com/pub/security/AST-2019-005.html
Revision History
Date Editor Revisions Made
August 26, 2019 Joshua Colp Initial revision
Asterisk Project Security Advisory - AST-2019-005
Copyright © 2019 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.