MADYNES Security Advisory : SIP toll fraud and authentication forward attack
Date of Discovery 5 May, 2007
Vendor1 (Cisco) was informed on 22 May 2007
Vendor 2 (OpenSer, voice-systems) was informed in 4 th October 2007
ID: KIPH11
Affected products
CallManager:
System version: 5.1.1.3000-5
Administration version: 1.1.0.0-1
OpenSer
SVN version until the 4 th October 2007
Version 1.2.2
Summary
The tested systems do not associate a Digest authentication to a dialog
which allows any user who can sniff the traffic to make its own calls on
behalf of the the sniffed device.
Synopsis
The tested implementations do not allow to check if the provided URI in
the Digest authentication header is the same as the REQUEST-URI of the
message, which allows an attacker to call any other extension. This is not
a simple replay attack.
They do not allowed to generate one-time nonces. These issues will allow a
malicious user able to sniff a Digest authentication from a regular user,
to call (by spoofing data) any extension on behalf of the user; as long as
the nonce does not expire.
The first vendor (Cisco) was informed in May 2007 and acknowledged the
vulnerability. The second vendor (OpenSer, voice-systems) was informed in
October 2007 and fixed the vulnerabity on the same day.
This vulnerability was identified by the Madynes research team at INRIA
Lorraine, using the Madynes VoIP fuzzer KIPH. This is one of the first
vulnerabilities published where advanced state tracking is required.
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.
Impact :
A malicious user perform toll fraud and call ID spoofing.
Resolution
OpenSer fixed the issue on the 4 th October.
The devel branch was enhanced to export a variable $adu which refer to this
field. It is easy now to check in config file whether it is equal or not
with r-uri:
if($adu != $ru)
{
# digest uri and request uri are different
}
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 KIF
POC: PoC code is available on request
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