Rule:

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Sid:

1636

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Summary:
This event is generated when an attempt is made to overflow a buffer in Xtramail.

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Impact:
An attacker can execute an arbitrary command with the privilege of the user running Xtramail, typically root.

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Detailed Information:
Xtramail is a Mail Transfer Agent ,normally listening on port 110 and 25. Older versions have a buffer overflow in the remote service when it is issued the large input strings in the Username field.

There are several unchecked buffers in XtraMail 1.11, which when overflowed will crash the server and cause a denial of service.

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Affected Systems:

	Artisoft XtraMail v1.11

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Attack Scenarios:
The POP3 server buffer can be overflowed by sending more than 1500 characters to the PASS argument.

The SMTP server buffer can be overflowed by sending more than 10,000 charcters in the HELO argument.

The username buffer for remote administration can be overflowed by sending more than 10,000 characters.

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Ease of Attack:
Simple.

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False Positives:
Certain types of binary file attachments could generate an event.

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False Negatives:
None known.

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Corrective Action:
Apply the appropriate patches

Upgrade to the latest non-affected version of the software. 

Block incoming attachments with .bat, .exe, .pif, and .scr extensions 

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Contributors:
Sourcefire Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>
Snort documentation contributed by Nawapong Nakjang (tony@ksc.net, tonie@thai.com)

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Additional References:

http://www.securityfocus.com/bid/791

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