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Re: Brute-forcing cached Windows login password hashes

To: Ben Greenberg <Ben.Greenberg@senet-int.com>, pen-test@securityfocus.com
Subject: Re: Brute-forcing cached Windows login password hashes
From: Carl Livitt <carllivitt@yahoo.com>
Date: Thu, 26 Jul 2007 07:39:00 -0700
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The hash algorithm is a salted MD4. It's impossible (ok, to be pedantic
it's mathematically infeasible) to use rainbow tables because of the
salting, so that leaves you with dictionary and brute-force.

The latest version of John and the MS Cache Hash patches are all
available from http://openwall.com/john/. I believe v1.7.2 is the latest
version.

Regards,
Carl


Ben Greenberg wrote:
> Greetings all,
>  
> My question is regarding the encrypted password hashes that Windows stores in
> the registry of the last 10 logins to a workstation.
>
> I read the original white paper written by Arnaud Pilon and I've used his
> cachedump tool to extract the password hashes from the registry. What I'm
> wondering is what type of hash those passwords use. Is it straight MD4? I
> know that each hash is salted with a machine-specific unique string. What I
> am unclear on is what exactly the password hash is and how it can be
> brute-forced. I know that there is a patch for John the Ripper, but every
> mention I can find refers to a two year old version of John. Does anyone know
> if the most recent version has this patch in it already? Also, is anyone
> familiar with any rainbow tables for cracking these passwords? Are rainbow
> tables possible for these hashes because of the salting?
>
> Thanks all.
>
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