Rule:

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Sid:
361

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Summary:
This event is generated when a remote user executes the SITE EXEC command in a session with an internal FTP server. This may indicate an attempt to exploit a vulnerability in the SITE EXEC command in wu-ftpd version 2.4.1.

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Impact:
Arbitrary code execution, leading to remote root compromise. The attacker must have a valid, non-anonymous FTP account on the server to attempt this exploit. 

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Detailed Information:
A misconfiguration in the pathnames.h configuration file in wu-ftpd 2.4.1 allows users to execute commands from /bin instead of ~username/bin. An attacker with a valid FTP account on the server can exploit this vulnerability to execute arbitrary shell code using the SITE EXEC command.

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Affected Systems:
Servers running Washington University wu-ftpd version 2.4.1 or earlier.

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Attack Scenarios:
An attacker logs into the system using a valid FTP account, and then executes arbitrary shell code to obtain root access to the server.

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Ease of Attack:
Simple. 

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False Positives:
If a legitimate remote user uses the SITE EXEC command, this rule may generate an event.

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False Negatives:
None known.

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Corrective Action:
Upgrade to a later version of the wu-ftp daemon.

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Contributors:
Original rule writer unknown.
Sourcefire Vulnerability Research Team
Sourcefire Technical Publications Team
Jen Harvey <jennifer.harvey@sourcefire.com>

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Additional References:

CERT
http://www.cert.org/advisories/CA-1995-16.html

OSVDB:
http://www.osvdb.org/8719

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