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Did a password has dump in 2008 domain - why some LM and not all NT hashes?

Posted on 2012-08-28
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Last Modified: 2012-09-19
I'm trying to better understand cracking passwords on my domain.  I used a utility to dump all the passwowrd hashes to a file, and then going through them with ophcrack to see if i can break any of them.

My question is some of the passwords have LM hashes and NT hashes, and so of course they're broken in seconds.
Others are JUST NT hashes, so they're taking longer to crack.

Why do some accounts have both NT and LM hashes and others just NT?
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Question by:Mystical_Ice
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by:Bruno PACI
ID: 38344780
Hi,

These accounts where probably already existing when your domain was a NT4 domain, and survived to the migration to AD domain.
In that case, these account were having a NT hash and this attribute has been conserved until today.

There's a Group Policy that permits you to prohibit storing of LM hashed password on domain accounts (look at http://support.microsoft.com/kb/299656) but as it does not remove existing "hashes" it will only become efficient on next password change.

So in your case, you should use this policy and add it to "Default Domain Policy" and "Domain Controllers Default Policy" and force everyone to change its password.

Have a good day.
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by:Mystical_Ice
ID: 38346363
If we have a few domain controllers that are running windows 2003, would that make a difference?  It shouldn't, right?

Our FSMO roles are all held on windows 2008 r2 servers
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Author Comment

by:Mystical_Ice
ID: 38346364
Also, some of the newest accounts have LM hashes.  There's one account that's 8 years old (the oldest one we have) and it has no LM hash
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Bruno PACI earned 1000 total points
ID: 38346717
Hi,

As far as I remember, a brand new domain directly created under Windows 2003 will not store LM hash by default... Domains migrated from NT4 will continue to store LM Hash until you force the policy I told you about in my previous post.

I don't know why some recent accounts have LM hash and old accounts don't... anyway, use the policy as explained in the Microsoft article to definitly prohibit LM hash generation.
Then, force users to change their password by any way you want (password expiration, check the box "user must change password at next connection", ...).

Have a nice day.
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