Rule:   --Sid: 325-- Summary: This is an intelligence gathering activity.-- Impact: The attacker may obtain a list of accounts existing on the target host.--Detailed Information:This event is generated when an attempt is made to use a finger command against a host with a username of "0".  A finger query against a vulnerable finger daemon may allow the attacker to obtain a list of accounts on the target system with some details for each account where present (such as time and source of the last login). Obtaining a list of accounts might precipitate further attacks such as password guessing, email attacks and other abuse.--Attack Scenarios: An attacker learns that the "sys" account exists on the system. He then proceeds to guess the password and is then able to gain remote access to the system.-- Ease of Attack: Simple, no exploit software required-- False Positives: None Known--False Negatives: None Known-- Corrective Action: Disable the finger daemon or limit the addresses that can access the service via firewall or TCP wrappers.--Contributors: Original rule written by Max Vision <vision@whitehats.com>Snort documentation contributed by Anton Chuvakin <http://www.chuvakin.org>Sourcefire Research TeamNigel Houghton <nigel.houghton@sourcefire.com>-- Additional References:Arachnids:http://www.whitehats.com/info/IDS378CVE:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-1999-0197Nessus:http://cgi.nessus.org/plugins/dump.php3?id=10069%20(Finger%20zero%20at%20host--