CERT^® Incident Note IN-2000-03

The CERT Coordination Center publishes incident notes to provide information about incidents to the Internet community.

911 Worm

Overview

A worm with variants known as "chode," "foreskin," "dickhair", "firkin," or "911" has received some attention over the last week. The National Infrastructure Protection Center issued a bulletin regarding this worm, available at

http://www.nipc.gov/nipc/advis00-038.htm

This worm spreads by taking advantage of unprotected Windows shares. For more information on a similar problem and relevant solutions, please see

http://www.cert.org/incident_notes/IN-2000-02.htm

Description

The "chode" worm affects Windows 98 systems with unprotected shares. It does not function properly on Windows NT systems. We have not completed testing on Windows 95 systems or Windows 2000 systems.

As of this writing, CERT/CC has not received any direct reports of systems infected with this worm, though we have received a small number of second-hand reports.

The worm consists of several batch files, and it takes the following steps.

CHODE.BAT calls RANDOM.BAT, which picks a target network and initial host from a set of predefined networks.

Once RANDOM.BAT picks an initial machine, CHODE.BAT increments over the addresses, and for each address it

• pings a machine and listens for an answer
• on machines that answer the ping, looks for any shares using "net view \\"
• tries to map the C drive on any machine with shares using "net use /yes j: \\\c"
• looks for j:\windows\win.com

If it maps C and finds win.com, it then

• checks for and deletes instances of "foreskin"
• checks for and deletes instances of "mstum.pif"
• checks for and deletes instances of "dickhair"
• checks for instances of chode

If chode is not found, it begins the process of trying to infect/replicate. It

• makes the directory j:\zx
• copies test.txt to j:\zx\test.txt

If the copy is successful, it

• deletes the zx directory
• makes the directory j:\progra~1/chode
• sets chode hidden using "attrib j:\progra~1\chode +h"
• copies all chode files to j: using "copy /y c:\progra~1\chode\*.* j:\progra~1\chode"

It then selects a random number based on the time. During this process, it creates a file called "cu##ent.bat", a file called "current.bat", and an environment variable called "time".

Based on the random number, it appends a file named "chocher.bat" to autoexec.bat with probability 1/10. The new autoexec.bat (with chocher.bat appended) then

• calls 911 with a probability of 3/6, attempting to use each of COM1 through COM4
• formats D,E,F,G,H drives, issues the message tHE cHOdE gOTcHA yOu sTUpID mOThER fUCKeR!!!!!!!!!!!!!!, and then formats the C drive, all with probability 1/6

Chode then copies ashield.pif, netstat.pif, and winsock.vbs to the startup folder on the victim machine. When Windows next starts on the victim machine, these files begin the process again.

The winsock.vbs file then deletes all files on the C drive on the 19th day of the month.

The initiating machine then starts again with a new IP address.

We encourage you to read CERT Incident Note IN-2000-02 for information on general solutions to the problem of unprotected Windows shares.

One notable variant (foreskin) of the worm described in this document randomly copies one of a set of batch files (named A.BAT, B.BAT, C.BAT...J.DAT) to a file called MSTUM.BAT. Other variants named dickhair and firkin are similar.

Other information

• http://www.antivirus.com/pc-cillin/vinfo/virusencyclo/default5.asp?VName=BAT_CHODE911
• http://vil.mcafee.com/dispVirus.asp?virus_k=98557
• http://www.sarc.com/avcenter/venc/data/bat.chode.worm.html
• http://www.sans.org/newlook/alerts/911worm.htm
• http://www.sophos.com/virusinfo/analyses/911a.html
• http://www.sophos.com/virusinfo/analyses/911b.html

Author: Shawn Hernan

CERT/CC Contact Information

Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
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CERT Coordination Center
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If you prefer to use DES, please call the CERT hotline for more information.

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http://www.cert.org/

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