Rule:

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Sid:
1845

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Summary:
This event is generated when a remote attacker sends an IMAP LIST command with a malformed and overly long argument to an internal IMAP server port. This may indicate an attempt to exploit a buffer overflow vulnerability in the IMAP LIST command.

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Impact:
Possible shell access on the IMAP server, leading to arbitrary code execution. The attacker must have a valid IMAP account on the mail server to attempt this exploit.

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Detailed Information:
When a LIST command with an overly long argument is sent to a vulnerable IMAP server, a buffer overflow condition may occur. This can allow an attacker to execute arbitrary code from the command shell. Note that this exploit can only be attempted by a user with a valid IMAP account.

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Affected Systems:
Any operating system running University of Washington imapd versions 10.234 or 12.264.

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Attack Scenarios:
An attacker with an IMAP account on the server can send a sufficiently long LIST command to the IMAP server, creating a buffer overflow condition. This can then allow the attacker to gain shell access on the compromised server, possibly leading to the execution of arbitrary code.

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Ease of Attack:
Simple. Exploits exist, but the user must have a valid IMAP account on the server.

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False Positives:
None known.

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False Negatives:
None known.

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Corrective Action:
Apply the patch for your current version of imapd appropriate to your operating system. 

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Contributors:
Original rule written by Brian Caswell <bmc@sourcefire.com>
Sourcefire Research Team
Sourcefire Technical Publications Team
Jennifer Harvey <jennifer.harvey@sourcefire.com>

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Additional References:
Bugtraq
http://www.securityfocus.com/bid/1110

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