The Cisco VPN Client uses weak encryption to store user and group passwords in your local profile file.
HAL 9000 coded a little tool to reveal the saved passwords from a given profile file.The Cisco Password Revealer along with the source code can be downloaded here.
The main problem of the method used to encrypt the passords is, that the whole procedure is deterministically and no user input is used. This effectively means that the encryption keys the Cisco Client calculates can also be calculated by any other program whensoever this programm knows the algorithm. This algorithm was now reversed.
More information : http://evilscientists.de/blog/?page_id=343
Et après ça, plus aucune raison de passer à une solution VPN avec ISA 2004 et des Smartcards :-)