[unisog] Password auditing

Russell Fulton r.fulton at auckland.ac.nz
Fri Jul 1 01:27:17 GMT 2005

First off, thanks to those who responded to my post on ssl and mysql.  I'm now investigating the native support in 4.0x

This time I have an idea for automated auditing of UNIX password (it may be extended to windows, I don't know).   Firstly I'd like to know if any of you can shoot holes in the proposal before I spend time implementing it and secondly I'd love to know of someone has already done this or someting that achieves the same end.

The idea is that the service would reside on a well secured ;) 'server', let's call it cracker.  Clients who want to use the service create an account on their system and set up permissions so that the account can see /etc/shadow (or perhaps we have a suid root program that cats /etc/shadow - probably safer - opinions?).  This account also has the ssh key for cracker in  its authroized_keys file.  We would also use ssh configuration to limit the scope for abuse of the account.

First visit to the client we suck up the password file and beat the *** out of it with John, this may take a little while.  Once this is complete the client is added to one of two pools depending on whether any weak passwords were found.

The first pool contains machines with weak passwords, for machines in this pool we regularly send admins email warning them of the weak password.  If they don't get changed we can either escalate the problem to the security team or perhaps disable the accounts (another suid program?). 

Machines in the second pool are visited regularly (daily?) we look for changes to the password file and try and break any new ones.  If we succeed the machine goes into the first pool

Any holes in this theory?  

The biggest problem I can see is that the 'server' will hold copies of all the password file, these should be encrypted while not actually being compared. I don't see this as being much different to an AD or Kerberos server.  

The second weakness is the account on the client with access to /etc/shadow, tips on securing this would be helpful.

Am I out of my tree?

Cheers, Russell

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