[Snort-sigs] SID 1886

Anton Chuvakin anton at ...1177...
Wed Feb 12 20:08:02 EST 2003


# This is a template for submitting snort signature descriptions to
# the snort.org website
#
# Ensure that your descriptions are your own
# and not the work of others.  References in the rules themselves
# should be used for linking to other's work.
#
# If you are unsure of some part of a rule, use that as a commentary
# and someone else perhaps will be able to fix it.
#
# $Id: snort-sid-template.txt,v 1.1 2002/10/09 13:06:31 cazz Exp $
#
#

Rule:

alert tcp $HTTP_SERVERS $HTTP_PORTS -> $EXTERNAL_NET any (msg:"ATTACK
RESPONSES id check returned apache"; flow:from_server,established;
content:"uid="; content:"(apache)"; classtype:bad-unknown; sid:1886;
rev:2;)

--
Sid: 1886

-- 

Summary: A post-compromise behavior indicating the use of a UNIX "id"
command

-- 

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

--
Detailed Information:

This signature triggers when a UNIX "id" command is used to confirm
the user name of the currently logged in user over any unencrypted
connection. Such connection can be either a legitimate telnet
connection or a result of spawning a shell on FTP, POP3, SMTP or other
port as a consequence of network exploit. The string "uid=" and
"(apache)" is an output of an "id" command indicating that the user
has "apache" account privileges, typically used by the web server
process.  Seeing such a response indicates that some user connected
over the network to a target web server and likely exploited the web
server to launch a shell.

--

Attack Scenarios: a buffer overflow exploit against the WWW server
results in "/bin/sh" being executed. An automated script performing an
attack, checks for the success of the exploit via an "id" command.

-- 

Ease of Attack: this post-attack behavior can accompany different
attacks

-- 

False Positives: the signature will trigger if a legitimate system
administrator executes the "id" command over the telnet connection
which uses one of the web ports, as defined in snort.conf

--
False Negatives: not known

-- 

Corrective Action: investigate the server for signs of compromise, run
the integrity checking software, look for other IDS alerts involving
the same IP addresses.

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

-- 
Additional References:





More information about the Snort-sigs mailing list