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
