XFOR: AUTH and EHLO Commands Cause Internet Mail Service to Stop

A malicious attacker might connect to the SMTP port of an Microsoft Exchange Server 5.0 or 5.5 computer and disrupt the Internet Mail Service by issuing specific sequences of AUTH or XAUTH commands. When this occurs, the following error message may be displayed:

Improper checking of bounds conditions on certain AUTH or XAUTH command sequences may result in a buffer overflow.

Microsoft has confirmed that this is a problem in Microsoft Exchange Serverversion 5.0.

A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next service pack that contains this fix. Contact Microsoft Technical Support for more information.

This fix has been posted to the following Internet location: Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.5. This problem has been corrected in the latest U.S. service pack for Microsoft Exchange Server version 5.5. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):