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Exchange 2007 attack

We have an Exchange 2007 server that runs on Windows 2003.  We have been getting failed login attempts on the server with generic user names like john, carol, support, administrator, admin and so on.  It's sometimes a few hundred every day.

The IP address is often different, as well as the source port.  The Logon type is always 10 and logon process User32.  We have Outlook Web Access enabled on this server, as well as POP3, IMAP4 and Exchange ActiveSync.  The server has a self-signed security certificate.

Our firewall is a Cisco ASA 5505.  I am trying to find out how they get to our server through the firewall and how this can be blocked.  I am not sure of this Exchange or Server 2003 related.

Below is an example of the many events from the security log on the server.

Event Type:      Failure Audit
Event Source:      Security
Event Category:      Logon/Logoff
Event ID:      529
Date:            12/9/2013
Time:            12:18:16 PM
User:            NT AUTHORITY\SYSTEM
Computer:      EXCHANGESERVER
Description:
Logon Failure:
       Reason:            Unknown user name or bad password
       User Name:      john
       Domain:            OURDOMAINNAME
       Logon Type:      10
       Logon Process:      User32  
       Authentication Package:      Negotiate
       Workstation Name:      EXCHANGESERVER
       Caller User Name:      EXCHANGESERVER$
       Caller Domain:      OURDOMAINNAME
       Caller Logon ID:      (0x0,0x3E7)
       Caller Process ID:      6948
       Transited Services:      -
       Source Network Address:      61.185.215.189
       Source Port:      56841
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rwottowa
Asked:
rwottowa
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1 Solution
 
Will SzymkowskiSenior Solution ArchitectCommented:
As you have posted in your question the IP is coming from a Public IP source. I have used whatismyipaddress.com to look this IP up and it appears that 61.185.215.189 is a public IP from China.

This is more then likely an attempt to hack your system. You might want to check your firewall and see what services are open. If you have something like 3389 (rdp) or something open on your Exchange server this can create a security hold which will allow users to attempt access on your machines.

You can also use whatismyipaddress.com and put your own external IP address in there and it will discover what "services" are enabled.

Will.
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rwottowaAuthor Commented:
Thanks Will, that was helpful.  I checked the firewall access rules and port 3389 was open to the email server.  It is disabled now so I'll monitor it closely and see if the attacks stop.

The IPs came from all over the world like Russia, China, Netherlands, USA and many more.   There really isn't a pattern to the origin of these attacks.
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Will SzymkowskiSenior Solution ArchitectCommented:
Something like this has happened to me before in other enviornments i have been exposed to. It is a huge security risk when you have 3389 opened to the outside world. I would think you should be fine now that it is being blocked by the firewall but i would monitor for the next couple of days.

Glad this helped your scenario.

Will.
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rwottowaAuthor Commented:
Closing 3389 (rdp) stopped the attacks right away and no new ones were recorded in the last 24 hours.  Thanks again!
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