PIX Privilege Escalation Vulnerability

[tbbunn () ctc net]

Back in May of last year I started doing research on any possible security flaws that exist in the Pix/ASA Finesse 
operating System, versions 7.1 and 7.2. I discovered that a design flaw that was previously unknown in Finesse will 
allow a level 0 user to escalate their privilege to level 15. I believe the vulnerability may originate in the local 
authentication service, thus not being possible to exploit when Radius and TACACS is implemented. Implementing AAA in 
any other way that keeps the passwords locally defined seems to have no affect on the vulnerability. I have been able 
to repeatedly bypass the privilege-exec login both locally, through the console and remotely, through a telnet 
connection. After many attempts I have found that the SSH service does not seem to suffer from the vulnerability. 
        I am now going to go over the simplicity of the exploit and I will be releasing a white paper hopefully sooner 
than later on the specifics of the underlying cause. Once a user has logged on to the user-exec (level0) of the device 
they will then be able to proceed with the <enable> command which should give you a login prompt. At this prompt if you 
move your cursor forward with a space or character(it doesn't matter if there are more then one), and then proceed to 
delete any spaces or characters, by holding down the backspace a second after deleting the last character it should 
immediately drop you into level 15 privilege-exec mode. This attack was originally performed on a PIX 515E running 
version 7.2 of Finesse. I will be posting all updates regarding this exploit as they come, and I apologize for it 
taking so long to release this information.

Terry B Bunn
LunarTEkINT Labs