Microsoft Security Bulletin (MS00-082)

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Patch Available for "Malformed MIME Header" Vulnerability

Originally posted: October 31, 2000

Summary

Microsoft has released a patch that eliminates a security
vulnerability in Microsoft(r) Exchange Server 5.5. The vulnerability
could enable a malicious user to cause an Exchange server to fail.

Frequently asked questions regarding this vulnerability
and the patch can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-082.asp

Issue

As part of its normal processing of incoming mails, Exchange server
checks for invalid values in the MIME header fields. However, if a
particular type of invalid value is present in certain fields, the
Exchange service will fail. Normal operations can be restored by
restarting the Exchange service and deleting the offending mail.

There is no capability via this vulnerability to add, delete or
modify emails, nor is there any capability to usurp administrative
privileges on the server. The vulnerability can be eliminated either
by apply the patch or Exchange 5.5 Service Pack 4, which is due to
be released shortly. Exchange 2000 is not affected by the
vulnerability.

Affected Software Versions

• Microsoft Exchange Server 5.5

Note: Exchange Server 2000 is not affected by the vulnerability.

Patch Availability

• Microsoft Exchange Server 5.5:
  http://www.microsoft.com/Downloads/Release.asp?ReleaseID=25443

Note: This patch can be applied atop systems running Exchange Server
5.5 Service Pack 3. It is included in Exchange Server 5.5 Service
Pack 4.

Note: Additional security patches are available at the Microsoft
Download Center

More Information

Please see the following references for more information related to
this issue.

• Frequently Asked Questions: Microsoft Security Bulletin MS00-082,
  http://www.microsoft.com/technet/security/bulletin/fq00-082.asp
• Microsoft Knowledge Base article Q275714 discusses this issue
  and will be available soon.
• Microsoft TechNet Security web site,
  http://www.microsoft.com/technet/security/default.asp

Obtaining Support on this Issue

This is a fully supported patch. Information on contacting Microsoft
Product Support Services is available at
http://support.microsoft.com/support/contact/default.asp.

Acknowledgments

Microsoft thanks Art Savelev (http://www.savelev.com) for reporting
this issue to us and working with us to protect customers.

Revisions

• October 31, 2000: Bulletin Created.

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Last Updated October 31, 2000

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