[Snort-sigs] SID 332

Anton Chuvakin anton at ...1177...
Wed Feb 12 20:26:10 EST 2003

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alert tcp $EXTERNAL_NET any -> $HOME_NET 79 (msg:"FINGER 0 query";
flow:to_server,established; content:"0"; reference:nessus,10069;
reference:arachnids,378; reference:arachnids,131;
reference:cve,CAN-1999-0197; classtype:attempted-recon; sid:332;

Sid: 332


Summary: An intelligence gathering attack against the finger daemon


Impact: attacker will obtain the list of some accounts existing on the
victim system

Detailed Information:

The signature is triggerred when an attempt to use a finger command
against a host with a username of "0".  Such finger query against the
vulnerable finger daemon allows the attacker to obtain a list of some
accounts existing on the target system with some details on each
account (such as time and source of the last login). Knowing the list
of accounts might facilitate a password guessing attacks, email
attacks and other abuse.


Attack Scenarios: an attacker learns that "sys" account exists on the
system. He then proceeds to guess the pasword remotely and connect to
the system.


Ease of Attack: very easy, no exploit software required


False Positives: not known

False Negatives: not known


Corrective Action: disable fingerd daemon or limit the addresses that
can access the service via firewall or TCP wrappers.

Contributors: Anton Chuvakin <http://www.chuvakin.org>

Additional References:


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