AST-2018-003: Crash With An Invalid SDP Fmtp Attribute

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Asterisk Project Security Advisory – AST-2018-003

Product Asterisk
Summary Crash with an invalid SDP fmtp attribute
Nature of Advisory Remote crash
Susceptibility Remote Authenticated Sessions
Severity Minor
Exploits Known No
Reported On January 15, 2018
Reported By Sandro Gauci
Posted On February 21, 2018
Last Updated On February 19, 2018
Advisory Contact Kevin Harwell
CVE Name

Description By crafting an SDP message body with an invalid fmtp
attribute Asterisk crashes when using the pjsip channel
driver because pjproject’s fmtp retrieval function fails to
check if fmtp value is empty (set empty if previously
parsed as invalid).

The severity of this vulnerability is lessened since an
endpoint must be authenticated prior to reaching the crash
point, or it’s configured with no authentication.

Resolution A stricter check is now done when pjproject retrieves the
fmtp attribute. Empty values are now properly handled.

Affected Versions
Product Release
Series
Asterisk Open Source 13.x All Releases
Asterisk Open Source 14.x All Releases
Asterisk Open Source 15.x All Releases
Certified Asterisk 13.18 All Releases

Corrected In
Product Release
Asterisk Open Source 13.19.2, 14.7.6, 15.2.2
Certified Asterisk 13.18-cert3

Patches
SVN URL Revision
http://downloads.asterisk.org/pub/security/AST-2018-003-13.diff Asterisk
13
http://downloads.asterisk.org/pub/security/AST-2018-003-14.diff Asterisk
14
http://downloads.asterisk.org/pub/security/AST-2018-003-15.diff Asterisk
15
http://downloads.asterisk.org/pub/security/AST-2018-003-13.18.diff Certified
Asterisk
13.18

Links https://issues.asterisk.org/jira/browse/ASTERISK-27583

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This document may be superseded by later versions; if so, the latest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-2018-003.pdf and
http://downloads.digium.com/pub/security/AST-2018-003.html

Revision History
Date Editor Revisions Made
January 30, 2018 Kevin Harwell Initial Revision

Asterisk Project Security Advisory – AST-2018-003
Copyright (c) 2018 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.