[Snort-sigs] SID 107

Christopher_Lubrecht at ...381... Christopher_Lubrecht at ...381...
Fri Mar 1 07:27:21 EST 2002


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Rule:
alert tcp $EXTERNAL_NET 16959 -> $HOME_NET any (msg:"BACKDOOR subseven DEFCON8 2.1
access"; content: "PWD"; content:"acidphreak"; nocase; flags: A+; sid:107;
classtype:misc-activity; rev:4;)
--
Sid:
107
--
Summary:
The Subseven DEFCON8 2.1 is a newer version of the popular Subseven trojan.  This
backdoor notifies the attacker when it has been installed, and allows the attacker
to obtain cached passwords, play audio files, capture screen shots and view
webcams.
--
Impact:
This trojan is very popular and highly scanned for. Articles document its use in a
variety of DDOS set ups and attacks. Attackers congregate in IRC for the specific
reason of detailing and bragging about  their subseven 'zombies'. Due to its
popularity, ease of use and high configurability, this is a dangerous trojan.
--
Detailed Information:
This trojan is mass distributed via methods such a newsgroup binary posting with
filenames such as "SexxxyMovie.mpeg.exe"(although any name could be used.).  The
trojan operates on port 16959, and once the client connects, prompts for a
password with a "PWD" prompt. The default password is "acidphreak" Once connected,
a banner will be displayed which contains the date, time  and "version: DEFCON8
2.1". This version of subseven only works on Windows 95 and 98.
--
Attack Scenarios:
Steve Gibson, of Gibson Research (ShieldsUP!), wrote a paper outlining one method
in which a 'zombie' trojan is used via IRC. The attacker gathers infected
machines, and uses them in an assault against a larger target, (usually via ICMP
flood). Individually, each machine's bandwidth would matter little to the target,
however when upwards of a 100 machines assault a target together, the effects are
devastating.
--
Ease of Attack:

--
False Positives:
It is possible to trip this signature with innocent traffic.
--
False Negatives:

--
Corrective Action:
The best method for removal of this trojan, is an anti-virus scanner, or a
subseven removal program. It is very difficult to remove manually, and not
recommended..
--
Contributors:
Christopher Lubrecht chris_lubrecht at ...382... initial research
--
Additional References:
http://grc.com/dos/grcdos.htm (Steve Gibson's paper)
http://www.europe.f-secure.com/v-descs/subseven.shtml
http://www.iss.net/security_center/alerts/advise30.php

















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