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Virus:Worm/Mydoom.BT
Date discovered:22/06/2005
Type:Worm
In the wild:Yes
Reported Infections:Low
Distribution Potential:Medium to high
Damage Potential:Low to medium
Static file:Yes
File size:24.576 Bytes
MD5 checksum:d102de7a1ec7b37db2cb0936e51f8509
VDF version:6.31.00.92

 General Methods of propagation:
   • Email
   • Peer to Peer


Aliases:
   •  Kaspersky: Email-Worm.Win32.Mydoom.au
   •  Grisoft: I-Worm/Mytob.JE
   •  VirusBuster: I-Worm.Mytob.EK1
   •  Eset: Win32/Mydoom.BH


Platforms / OS:
   • Windows 98
   • Windows 98 SE
   • Windows NT
   • Windows ME
   • Windows 2000
   • Windows XP


Side effects:
   • Drops a malicious file
   • Uses its own Email engine
   • Registry modification


Right after execution the following information is displayed:


 Files It copies itself to the following location:
   • %SYSDIR%\caca.exe



The following file is created:

%SYSDIR%\systemcall.dll Further investigation pointed out that this file is malware, too. Detected as: Worm/Mydoom.BT.DLL

 Registry The following registry key is added in order to run the process after reboot:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   • "Caca"="%SYSDIR%\caca.exe"



The following registry key is added:

HKCR\CLSID\{E6FB5E20-DE35-11CF-9C87-00AA005127ED}\InProcServer32
   • @="%SYSDIR%\systemcall.dll"
   • "ThreadingModel"="Apartment"

 Email It contains an integrated SMTP engine in order to send emails. A direct connection with the destination server will be established. The characteristics are described in the following:


From:
The sender address is spoofed.
Generated addresses. Please do not assume that it was the sender's intention to send this email to you. He might not know about his infection or might not even be infected at all. Furthermore it is possible that you will receive bounced emails telling you that you are infected. This might also not be the case.


To:
– Email addresses found in specific files on the system.
 Email addresses gathered from WAB (Windows Address Book)
– Generated addresses


Subject:
One of the following:
   • Error
   • Status
   • hello
   • Server Report
   • Mail Transaction Failed
   • Mail Delivery System



Body:
The body of the email is one of the lines:
   • Mail transaction failed. Partial message is available.
   • The message contains Unicode characters and has been sent as a binary attachment.
   • The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.


Attachment:
The filename of the attachment is constructed out of the following:

–  It starts with one of the following:
   • body
   • message
   • test
   • data
   • file
   • text
   • doc
   • readme
   • document

    The file extension is one of the following:
   • bat
   • cmd
   • exe
   • scr
   • pif
   • zip

The attachment is a copy of the malware itself.

The attachment is an archive containing a copy of the malware itself.



The email looks like the following:


 Mailing Search addresses:
It searches the following files for email addresses:
   • wab
   • adb
   • tbb
   • dbx
   • php
   • sht
   • htm
   • txt
   • tmp


Address generation for TO and FROM fields:
To generate addresses it uses the following strings:
   • sandra; linda; julie; jimmy; jerry; helen; debby; claudia; brenda;
      anna; brent; adam; ted; fred; jack; bill; stan; smith; steve; matt;
      dave; dan; joe; jane; bob; robert; peter; tom; ray; mary; serg; brian;
      jim; maria; leo; jose; andrew; sam; george; david; kevin; mike; james;
      michael; alex; john

It combines this with domains from the following list or from addresses found in files on the system

The domain is one of the following:
   • hotmail.com
   • yahoo.com
   • msn.com
   • aol.com


Avoid addresses:
It does not send emails to addresses containing one of the following strings:
   • accoun; certific; listserv; ntivi; support; icrosoft; admin; page;
      the.bat; gold-certs; feste; submit; not; help; service; privacy;
      somebody; soft; contact; site; rating; bugs; you; your; someone;
      anyone; nothing; nobody; noone; webmaster; postmaster; samples; info;
      root; mozilla; utgers.ed; tanford.e; pgp; acketst; secur; isc.o;
      isi.e; ripe.; arin.; sendmail; rfc-ed; ietf; iana; usenet; fido;
      linux; kernel; google; ibm.com; fsf.; gnu; mit.e; bsd; math; unix;
      berkeley; foo.; .mil; gov.; .gov; ruslis; nodomai; mydomai; example;
      inpris; borlan; sopho; panda; icrosof; syma; avp; .edu; -._!; -._!@;
      abuse; www


Prepend MX strings:
In order to get the IP address of the mail server it has the ability to prepend the following strings to the domain name:
   • gate.
   • ns.
   • relay.
   • mail1.
   • mxs.
   • mx1.
   • smtp.
   • mail.
   • mx.

 P2P In order to infect other systems in the Peer to Peer network community the following action is performed:


   It retrieves the shared folder by querying the following registry key:
   • HKCU\Software\Kazaa\Transfer

   If successful, the following files are created:
   • nuke2004
   • office_crack
   • rootkitXP
   • winamp5
   • icq2004-final
   • activation_crack
   • strip-girl-2.0bdcom_patches

   These files are copies of the malware itself.

 Backdoor The following port is opened:

%malware execution directory%\%executed file% on TCP port 3127 in order to provide a Socks 4 proxy server.

 DoS Right after it becomes active, it starts a DoS attack against the following destination:
   • www.sco.com

 File details Programming language:
The malware program was written in MS Visual C++.


Runtime packer:
In order to aggravate detection and reduce size of the file it is packed with the following runtime packer:
   • UPX

Description inserted by Irina Boldea on Monday, October 23, 2006
Description updated by Irina Boldea on Monday, November 6, 2006

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