exchange 2003 random internal e-mail addresses in outgoing queue

Hey guys,

My client is running Exchange 2003 SBS (i just took them on). Their outgoing exchange queues are hacked with RANDOM internal e-mail addresses (xyaj38s@company.com).

I've enabled sender/recipient filtering, ensured it's not an open relay, scanned the server for viruses (did find a backdoor trojan on it, i believe it's removed). I also changed everyone's passwords... Turned off windows authentication.

The queues are still filling up. Is it possible someone's machine in the office is compromised?

Anything else I should look at?

Thanks guys.
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tamaneriAsked:
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Glen KnightConnect With a Mentor Commented:
Looks like you've done most of everything else.  I'd say the next place to look is definitely the client machines.
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jbvernejConnect With a Mentor Commented:
Hello,

Your messages in queues:
does they seem to be fake NDR messages (Non Delivery Report)  ?
(IE a NDR for a message that was never send ) ?
If yes, you could be under External NDR attack.

here a  procedure to cleanup:
kb886208 - Exchange queues fill with many non-delivery reports from the postmaster account in Small Business Server 2003
http://support.microsoft.com/kb/886208/en-us
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Manpreet SIngh KhatraConnect With a Mentor Solutions Architect, Project LeadCommented:
Restart the services or the server and check.

- Rancy
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tamaneriAuthor Commented:
Thanks for the input guys.

Turns out it was a root-kit on the server itself. I ran the following programs to remove all of the malware/viruses/rootkit

1) MBAM
2) TDSS Killer
3) Kaspersky Virus Removal Tool (just to ensure it was clean).

The virus/root-kit that TDSSKILLER found was a file called sbscrexe.exe in c:\windows\system32.

Thanks for your help in this matter. Queues look like they're going to remain clean.
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tamaneriAuthor Commented:
Just to update you guys... It took a couple of hours, but I have some more messages in the queues. I didn't have much time to spend looking at the client machines while I was on site today. I've instructed them to turn off their computers when they leave for the day so I can determine if it's a server-related hacking issue, or a desktop virus/malware causing the problem.
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