[Snort-sigs] SID 328
anton at ...1177...
Thu Jan 30 20:40:01 EST 2003
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# $Id: snort-sid-template.txt,v 1.1 2002/10/09 13:06:31 cazz Exp $
alert tcp $EXTERNAL_NET any -> $HOME_NET 79 (msg:"FINGER bomb
attempt"; flow:to_server,established; content:"@@";
classtype:attempted-dos; sid:328; rev:5;)
Summary: A Denial-of-Service attack against a finger daemon
Impact: attacker will overload the target machine or crash the finger daemon
The signature is triggerred when a specifially crafted finger query is
directed at a target UNIX machine. Finger daemon is used to provide
information about the UNIX system users. It used to be installed and
enabled by default on most UNIX/Linux systems. The attack will crash or
overload the vulnerable machines by causing the finger daemon to go into a
loop. The attack abuses the buggy "finger forwarding" functionality,
normally used to forward queries to a third partuy machine (a security
risk in itself).
Attack Scenarios: an attacker runs an attack and slows the machine
Ease of Attack: very simple, no exploit software is required, just a
specially formatted finger query
False Positives: not known
False Negatives: not known
Corrective Action: disable fingerd daemon, patch it or limit the addresses
that can access the service via firewall or TCP wrappers.
Contributors: Anton Chuvakin <http://www.chuvakin.org>
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