[Full-disclosure] CallManager and OpeSer toll fraud and authentication forward attack

Type securityvulns
Reporter Securityvulns
Modified 2007-10-15T00:00:00


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


Affected products


System version:

Administration version:


SVN version until the 4 th October 2007

Version 1.2.2


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.


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.


  • 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.


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



  • 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