Rule:

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Sid:
658

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Summary:
This event is generated when a denial of service is attempted on a Microsoft Exchange mail server.

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Impact:
Denial of service.  This will cause the Exchange server to fail.  

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Detailed Information:
A vulnerability exists in Microsoft Exchange 5.5 that causes a denial of service if a MIME header contains the string 'charset = ""'.  The Exchange server does not properly handle this MIME header string, causing it to crash.

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Affected Systems:
Microsoft Exchange server 5.5

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Attack Scenarios:
An attacker can supply a malicious string in the MIME header causing the Exchange server to fail. 

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Ease of Attack:
Easy.  An attacker can telnet to port 25 of the Exchange server, start a dialogue with the server, and supply the malicious string in the MIME header.

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False Positives:
None Known.

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False Negatives:
None Known.

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Corrective Action:
Apply the appropriate patch or upgrade to Exchange 5.5 service Pack 4.

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Contributors:
Original rule writer unknown
Sourcefire Research Team
Judy Novak <judy.novak@sourcefire.com>

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Additional References:

Microsoft:
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/ms00-082.asp 

Miscellaneous:
http://packetstormsecurity.nl/0011-exploits/exchange.dos.txt


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