The Madynes research team has reported a vulnerability in Cisco IP Phone 7940, which can be exploited by malicious people to cause a DoS (Denial of Service).

The vulnerability is caused due to the improper handling of SIP INVITE messages. This can be exploited to deny legitimate calls or to reboot the device by sending a series of SIP INVITE messages containing a "Request-URI" without a username.

Successful exploitation requires knowledge of a valid userid on the target phone.

NOTE: The vendor reportedly could not confirm a device reboot via SIP INVITE messages and states that a device is not affected when registered with a Cisco Unified Communications Manager (CUCM) server.

The vulnerability is reported in firmware version P0S3-08-7-00. Other versions may also be affected.

Solution
Restrict network access to the vulnerable device.

Provided and/or discovered by
Madynes research team at INRIA Lorraine.

Changelog
Further details available in Customer Area

Original Advisory
http://lists.grok.org.uk/pipermail/full-disclosure/2007-December/058837.html

Deep Links
Links available in Customer Area