[Snort-sigs] SID 1361

Anton Chuvakin anton at ...1177...
Thu Apr 17 15:20:04 EDT 2003

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# $Id: snort-sid-1334.txt,v 1.1 2003/02/18 22:31:30 anton Exp anton $

(msg:"WEB-ATTACKS nmap command attempt"; flow:to_server,established;
content:"nmap%20";nocase; sid:1361; classtype:web-application-attack;

Sid: 1361

Summary: A web command execution attack involving the use of a
"nmap" command

Impact: attacker might have gained an ability to execute system commands
remotely on the system

Detailed Information: This signature triggers when a "nmap" command
is used over a plain-text (unencrypted) connection on one of the
specified web ports to the target web server. The "nmap" scanner may
be used to perform information gathering activities, such as port
scanning and OS fingerprinting. The signature looks for the "nmap"
command in the client to web server network traffic and does not
indicate whether the command was actually successful. The presence of
the "nmap" command in the URL indicates that an attacker attempted to
trick the web server into executing system in non-interactive mode
i.e. without a valid shell session. Another case when this signature
might trigger is unencrypted HTTP tunneling connection to the server
or a shell connection through an exploit of the web server.

Attack Scenarios: An attacker uses a "nmap" command to
perform anonymous reconnaissance and scan the machines within the DMZ.

Ease of Attack: very easy, no exploit software required

False Positives: none known

False Negatives: none known

Corrective Action: check the web server software for vulnerabilities
and possible upgrade the system to the latest version, also
investigate the server for signs of compromise

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

Additional References:

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