Atstake Security Advisory A090403-1 – The Asterisk software PBX has a flaw in its SIP protocol implementation that could allow an attacker to obtain remote and unauthenticated access to the system.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/31591/a090403-1.txt
Source: https://packetstormsecurity.com/files/31591/Atstake-Security-Advisory-03-09-04.1.html