Exchange 2003 Queue Filling up with PayPal/National Lottery & others

Posted on 2010-11-30
Last Modified: 2012-06-27
Got an exchange server queue just constantly filling with thousands of messages from  admin @national lottery or paypal security and ebay or some other rubbish. its rendering email useless and me clearing the queue feels like a futile gesture. So.... We are exchange 2003 SP2 on Server 2003 R2. I followed and looked and disabled authenticated relaying - restarted smtp services  etc - no joy. AV scan gives some tracking cookies - ..... would very much appreciate your assistance. thanks in advance.
Question by:pabby061203
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LVL 76

Accepted Solution

Alan Hardisty earned 500 total points
ID: 34241866
LVL 76

Expert Comment

by:Alan Hardisty
ID: 34241895
Essentially - you have an account that some hacker has guessed / brute force attacked and now is sending out mail via your server using this username / password.

One simple solution is to change the Authentication on your SMTP Virtual Server to only allow Anonymous Access - then restart the SMTP Service - which will stop them dead, but if you have anyone needing to send mail via your server using credentials - as soon as you turn this back on - the hacker will have access again unless you change ALL your passwords.

So - you can identify the account, change the password and then restart SMTP service or disable Basic / Integrated Windows Authentication on your SMTP Virtual Server and then restart the SMTP Service.


Author Comment

ID: 34282009

Here's an update on this one.

It seemed to stop for most of the day, one day last week, and I thought that we had managed to fix it but checking from home at 6:30 I saw 6.5k messages in the queue again. The situation was also being made unclear by the fact that the ISP was throttling us very heavily during work hours - so I though that maybe, somehow,  there was not enough bandwidth for it to hit us properly - as the queue seemed empty most of that day. So as a test I changed the gateway  of the mail server to point down another line that we have, that I knew to have decent bandwidth and waited to see what happened. Nothing. Its been like that for 4 days now - I have left it as is and email is functioning ok. No thousands of mail in the queue.Its just working fine. One consultant I know, who has more experince than I do - his 30 odd years to my 12 -  told me that he felt it was malware possibly on one of the servers but AV scans etc has found little to convince me.  So, ultimately, we have routed the mail down a different path to a different router and we no longer appear to have the issue. If it was an external attack as mentioned above and the attacker relies on the external IP as being the mail server - changing the mail servers external IP may have worked.
     I still feel a bit puzzled by it as we haven't completely convinced ourselves as to what the issue really was. By changing the routing we might never know now but the pressure was on to get the mail service going again. I did change some account passwords  and I did do a good few virus/spyware  scans but there hasn't been a point at which we have had an "Eureka" moment.  Happy to award the points to you Alan as you have added a scenario and valuable advice -thanks again.

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