The modified SMB Server

In order for the client to download the images, the client needs to 'logon' to the Lanman server. Windows NT seems to do this without even asking the user for confirmation. Windows NT simply forwards the username and encrypted version of the user's password to the Lanman server. The Lanman server code has been modified slightly to record Usernames and "Hashed Passwords" of the victims. Also the code has been modified to supply the client with a fixed "Challenge seed value" for password encryption. (Thus making it even easier to decode the client passwords in the future.) See NT Password Dictionary Attack for where I got the Lanman server idea.

What's the big deal?

First of all, no remote web site should be able to record your username. If they do, then can compile junk email lists and sell your name. Secondly, if they have information on what your password might be, and they know what site you came from, they can gain access to your computer or local account. (Thus compromising your security with you never knowing about it.) It is fairly easy to unencrypt a MS password if the challenge has set to zero via dictionary attacks. Sequential search brute force attacks work as well if you can guess what types of characters are most common in the password. Yes, it is time consuming, but if your account gets hacked, is it really worth it? It is interesting to note that in theory someone could setup a Lanman server that make a simultaneous connection back to the client as a connection comes in. By simply relaying the same challenge and password back to the client, the remote server could gain network access to the vulnerable client.

Did you really get my username & hashed password?

Take a look at the log so far. Remember these passwords are easier to unencrypt because the challenge response is set to all zeros! If your client connects with a plaintext password, I do NOT show it in the logs, although some machines have been connecting with non encrypted passwords. Also I do not show the entire encrypted password in the log to protect the user. Notice that the most common account & password I get is "Administrator".

IF YOUR PASSWORD IS CAUGHT, CHANGE IT A.S.A.P!!


IE BUG #4 was discovered by Aaron Spangler. First posted Mar 14,1997