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Failure audit Kerberos error 0x6 Event ID 672

Posted on 2011-02-24
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Last Modified: 2012-05-11
Hi,

I have been getting failure audit messages in the security log on all DC's in the domain.
It looks like somebody is trying to get into the AD from a member server in our domain.

The user name "sw1tchu$er" doesn't exist in the domain.
I have also noticed that the same was happening for the existing "support" user account that we have on the domain. Therefore I have disable this account, causing the Event ID 675 listed below (it was getting locked out before it got disabled).

Both events have the same client IP address. Changing the IP address didn't stop the problem.
When the member server was shut down, the failure audit messages stopped.
I have also tried a few programs like Spybot, HijackThis etc. without any success on the member server.
All servers in the AD (Windows 2003 Server) are fully patched and have AV software installed.
The firewall (CISCO ASA) is in stealth mode, no open ports are visible.

I am open to any suggestions.
Thanks in advance.


Failure audit Event ID 672

Authentication Ticket Request:
       User Name:            sw1tchu$er
       Supplied Realm Name:      mydomain.LOCAL
       User ID:                  -
       Service Name:            krbtgt/mydomain.LOCAL
       Service ID:            -
       Ticket Options:            0x40810010
       Result Code:            0x6
       Ticket Encryption Type:      -
       Pre-Authentication Type:      -
       Client Address:            member server IP
       Certificate Issuer Name:      
       Certificate Serial Number:      
       Certificate Thumbprint:      


Failure audit Event ID 675

Authentication Ticket Request:
       User Name:            support
       Supplied Realm Name:      mydomain.local
       User ID:                  -
       Service Name:            krbtgt/mydomain.local
       Service ID:            -
       Ticket Options:            0x40810010
       Result Code:            0x12
       Ticket Encryption Type:      -
       Pre-Authentication Type:      -
       Client Address:            member server IP
       Certificate Issuer Name:      
       Certificate Serial Number:      
       Certificate Thumbprint:      


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Question by:drula
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1 Comment
 
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Adam Brown earned 2000 total points
ID: 34974505
The 672 error looks like someone put their password in as their user name. That can happen, and it is always logged with the 672 error when it happens. Usually if you look at the following success events if they are logged you can figure out which user is having issues. The 675 error looks to be a logon hours restriction violation. When a user is logged in when they have logon restrictions invoked on their account, the 675 event (with result code of 12) signifies that they are still logged in.

http://www.windowsecurity.com/articles/Kerberos-Authentication-Events.html will give you more information.
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