[Snort-sigs] SID 1330
anton at ...1177...
Tue Feb 18 19:59:15 EST 2003
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# $Id: snort-sid-1328.txt,v 1.1 2003/02/18 20:39:03 anton Exp anton $
Rule: alert tcp $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS
(msg:"WEB-ATTACKS wget command attempt"; flow:to_server,established;
content:"wget%20";nocase; sid:1330; classtype:web-application-attack;
Summary: A post-compromise behavior indicating the use of a UNIX "wget"
Impact: attacker might have gained an ability to execute commands
remotely on the system and an ability to download file onto the web
Detailed Information: This signature triggers when a UNIX "wget"
command is used over a plain-text (unencrypted) connection on one of
the specified web ports to the target web server. The "wget" command
is used to download a file via HTTP or FTP connection to a UNIX
machine. Using "wget", the attackers might be able to download a local
exploit, IRC daemon or DDoS agent onto the server. The signature looks
for the "wget" command in the URL part of the client to web server
connection and does not indicate whether the command was actually
successful in downloading the files. The presence of the "wget" 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.
Attack Scenarios: An attacker uses a "wget" command via a web
server connection to load a copy of ptrace exploit onto a Linux
machine. He then executes the exploit over the web and obtains root
Ease of Attack: very easy, no exploit software required
False Positives: the signature will trigger if the string "wget " is
present in the URL requested from the web server, such as a part of a long
False Negatives: non 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>
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