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59

answers:

1

I am working to set up SSO for our intranet the idea is that a user would login to their workstation using their active directory username and password. Then a small application would run at login that would send some uniquely identifiable information,user name, and computers MAC address to the server were it would be entered into a database with a time stamp. Then when the user accesses the intranet a java applet would send the users mac address to the server and compare it to the database entry to see if it finds a match within a given time frame, if it does then it signs the user in and removes the entry from the database.

Unfortunately our intranet is not running on IIS so I can't use NTLM to do authentication which would be easier but not cross browser compatible which is one of the requirements. NTLM is also not an option because our intranet is only accessible in the form intranet.company.com and as far as I know NTLM does not work with addresses in that form.

Okay now onto the question. I am currently in the process of creating the client authentication application in C++ and need a way to get some unique identifier or token that would differentiate a legitimately logged in Active Directory user from some one who got a hold of the application and changed their local username to an AD user.

Yes I know this is probably the wrong way of doing it but right now it seems like the only option. If you have any suggestions beyond not doing it please let me know. Also I am aware of the huge gaping security hole it creates if you can think of a way to patch up that hole with out NTLM be sure to let me know.

A: 

AD is just Microsoft's implementation of Kerberos. One of the core features if Kerberos is to create such permission tickets. So, on that side your solution is not a hack at all. It's just the validation part that looks like a car crash.

However, I'm entirely lost at the client-side problem you have. The entire point of AD or Kerberos in general is that you can't spoof an authenticated user. You just ask the OS for a ticket for the logged-in user. It doesn't matter who gets hold of your app, or or what his local username would be. The OS knows precisely who is logged in.

MSalters
That is exactly what I am wanting to do but I seem to be lost on how to get that ticket.As far as the gaping hole goes, all an attacker needs to do is know the mac-address and time that a person will be logging in and he can successfully spoof that user just as they log in and before they access the intranet for the first time. Now I know its not likely but it is still a hole.
Robert F.