[NEWS] Remote Crash Vulnerability in Asterisk's Skinny Channel Driver

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Remote Crash Vulnerability in Asterisk's Skinny Channel Driver
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SUMMARY

A security vulnerability in Asterisk's Skinny protocol allows remote
attackers to cause the Asterisk server to crash by sending it a malformed
Skinny packet.

DETAILS

Vulnerable Systems:
* Asterisk Open Source versions prior to 1.4.8
* AsteriskNOW prerelease versions prior to beta7
* Asterisk Appliance Developer Kit versions prior to 0.5.0
* s800i (Asterisk Appliance) versions prior to 1.0.2

Immune Systems:
* Asterisk Open Source version 1.4.8
* AsteriskNOW Beta7
* Asterisk Appliance Developer Kit version 0.5.0
* s800i (Asterisk Appliance) version 1.0.2

The Asterisk Skinny channel driver, chan_skinny, has a remotely
exploitable crash vulnerability. A segfault can occur when Asterisk
receives a packet where the claimed length of the data is between 0 and 3,
followed by length + 4 or more bytes, due to an overly large memcpy. The
side effects of this extremely large memcpy have not been investigated.

Resolution:
All users that have chan_skinny enabled should upgrade to the appropriate
version listed in the corrected in section of this advisory. As a
workaround, users who do not require chan_skinny may add the line "noload
=> chan_skinny.so" (without quotes) to /etc/asterisk/modules.conf, and
restart Asterisk.

ADDITIONAL INFORMATION

The information has been provided by <mailto:jparker@digium.com> Jason
Parker.
The original article can be found at:
<http://ftp.digium.com/pub/asa/ASA-2007-016.pdf>

http://ftp.digium.com/pub/asa/ASA-2007-016.pdf

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