RE: Voice over IP

[John Bumgarner <JBumgarner () matrixnetworking net>]

Brandon,

We are a Cisco VAR and have been using Cisco's VoIP products for 18 months.
We have spoken with Cisco concerning security, which is not their priority.
Both the Call Manager and the phones have problems.

Some security flaws:

(1) sniffing the traffic is one, which provides any items key into the phone
(i.e. SSN, PIN #).  This is great if you want to access banking records.

(2) killing the Call Manager,  this product has several buffer overflows.
One overflow via HTTP allows you to gain access to entire phone system.  

(3) cracking the admin screen for both the Call Manager and the Phones.  The
web access screen for both the devices can be cracked.  The only way to
prevent this is with strong passwords and password procedures.

(4) Of course the Phones can be killed with DoS.  

(5) There are also some proprietary tools that can capture and decompress
the calls.  You must have access to the internal network for this, which
usually not a problem (especially with wireless).

The only item that I have not tested is: sending traffic to the phones
through the Internet to crash or control the phones or Call Manager.

I hope that this information helps.

John Bumgarner, MA, CISSP





-----Original Message-----
From: Young, Brandon [mailto:byoung () Calence com]
Sent: Thursday, June 14, 2001 11:48
To: 'pen-test () securityfocus com'
Subject: Voice over IP


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All,

A couple of colleagues and I are working on a security audit for a
VOIP system. Anyone know of any exploits and vulnerabilities that may
exist with Cisco's call manager? One thing we have found is that the
traffic can be sniffed during phone calls. TCP is used for the
initial connection setup and then once the phone has setup a session
to the call manager it then uses the RTP protocol. We found that the
conversation is placed in the PCMU audio codec. We are looking to
find a way to extract the payloads and reassemble the audio so that
we can play back the phone conversations.  We are also looking at 
launching a man in the middle attack and getting access to the
conversation and trying and listen to it in real time instead of
capturing and replaying. Any ideas on some possible ways to execute
this? 

Thanks in advance,

//CALENCE
Brandon Young
Consultant - Consulting Services
480.889.9736
byoung () calence com
www.calence.com




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