Rule: 

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Sid:
330

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Summary: 
This is an intelligence gathering activity. This event is indicative of a connection laundering attack against the finger daemon

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Impact: 
The attacker may obtain information about a third party host without making a direct connection to that host.

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Detailed Information:
The event is generated when an attempt to use a machine to run
finger queries against a third party UNIX system is attempted. 

The attack utilizes "finger forwarding" functionality, normally used to forward queries to a third party machine. The information is obtained without a direct connection to the said third party, since the target system performs a connection to the third party host for the attacker. 

The Finger daemon is used to provide information about users on a UNIX system. It used to be installed and enabled by default on most UNIX/Linux systems. The attack if successful, will confirm that the target host will try to forward queries.

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Attack Scenarios: 
An attacker runs a finger query and obtains information about the root account. He then proceeds to compromise the system using the obtained data as a basis for the compromise.

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Ease of Attack: 
Simple, no exploit software required

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False Positives: 
None Known

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False Negatives: 
None Known

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Corrective Action: 
Disable the finger daemon or upgrade to a daemon without finger forwarding functionality

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Contributors: 
Original rule written by Max Vision <vision@whitehats.com>
Snort documentation contributed by Anton Chuvakin <http://www.chuvakin.org>
Sourcefire Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

Nessus:
http://cgi.nessus.org/plugins/dump.php3?id=10073

CVE:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-1999-0105

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