AST-2017-002: Buffer Overrun In PJSIP Transaction Layer

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Asterisk Project Security Advisory – AST-2017-002

Product Asterisk
Summary Buffer Overrun in PJSIP transaction layer
Nature of Advisory Buffer Overrun/Crash
Susceptibility Remote Unauthenticated Sessions
Severity Critical
Exploits Known No
Reported On 12 April, 2017
Reported By Sandro Gauci
Posted On
Last Updated On April 13, 2017
Advisory Contact Mark Michelson
CVE Name

Description A remote crash can be triggered by sending a SIP packet to
Asterisk with a specially crafted CSeq header and a Via
header with no branch parameter. The issue is that the
PJSIP RFC 2543 transaction key generation algorithm does
not allocate a large enough buffer. By overrunning the
buffer, the memory allocation table becomes corrupted,
leading to an eventual crash.

This issue is in PJSIP, and so the issue can be fixed
without performing an upgrade of Asterisk at all. However,
we are releasing a new version of Asterisk with the bundled
PJProject updated to include the fix.

If you are running Asterisk with chan_sip, this issue does
not affect you.

Resolution A patch created by the Asterisk team has been submitted and
accepted by the PJProject maintainers.

Affected Versions
Product Release
Series
Asterisk Open Source 11.x Unaffected
Asterisk Open Source 13.x All versions
Asterisk Open Source 14.x All versions
Certified Asterisk 13.13 All versions

Corrected In
Product Release
Asterisk Open Source 13.15.1, 14.4.1
Certified Asterisk 13.13-cert4

Patches
SVN URL Revision

Links https://issues.asterisk.org/jira/browse/ASTERISK-26938

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This document may be superseded by later versions; if so, the latest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-2017-002.pdf and
http://downloads.digium.com/pub/security/AST-2017-002.html

Revision History
Date Editor Revisions Made
12 April, 2017 Mark Michelson Initial report created

Asterisk Project Security Advisory – AST-2017-002
Copyright (c) 2017 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.

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