Threat Descriptons



Category :


Type :


Aliases :

MyDoom.Y, W32.Mydoom.W@mm, I-Worm.MyDoom.gen, I-Worm.Mydoom.x


A new variant of MyDoom worm - Mydoom.Y, was found on September 14th, 2004. It spreads in emails with different subject and body texts, downloads and activates a backdoor.This variant was already detected generically as I-Worm.MyDoom.gen. This variant seems to launch a DDoS attack against


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Technical Details

The worm is a PE executable file 88640 bytes long packed with FSG file compressor. The unpacked file's size is over 118 KiB.

Installation to system

When run, the worm creates a mutex 'Sept-Symantec-Attack', copies itself as "oz11111.exe" to Windows System Directory and as "oz2.exe" in the main Windows folder.

It drops several other components, registry keys are created for all the executables as follows:

(First tries HKLM and falls back into HKCU if the registry key can't be openened)

  • [Software\Microsoft\Windows\CurrentVersion\Run] "" = "%WinSysDir%\oz11111.exe"
  • [Software\Microsoft\Windows\CurrentVersion\Run] "Microsoft Windows updaterD" = "%WinSysDir%\log32zx.exe"
  • [Software\Microsoft\Windows\CurrentVersion\Run] "Services" = "%WinTempDir%\services.exe"
  • [Software\Microsoft\Windows\CurrentVersion\Run] "oz2" = "%WinDir%\oz2.exe"
  • [Software\Microsoft\Windows\CurrentVersion\Run] "Downxz" = "%WinSysDir%\Downxz.bat"

where "%WinSysDir%" represents Windows System directory, "%WinDir%" the main Windows folder and "%WinTempDir%" the Windows Temporary files folder.

The worm will also drop a text file named 'About_Mydoom.txt' in the Windows System folder, with contents refering to the actions performed by the worm, the text in the file follows:

------------------- About_Mydoom.txt contents ------------------

1- ATTACK On Sept 29 2004 starting at 2
2- drops yahoo keylogger that open 4321, http://victim_ip:4321/
3- drops 2 pictures that will not be showing to the victim
4- drops a downxz.bat which download Bacdoor.Nemog.c
5- drops services.exe , zincite.a
6- Retrieves email addresses from the Outlook address book and files on
 fixed disks, ram disks, and in the following registry key and folders:
%Userprofile%\Local Settings\Temporary Internet Files
%Userprofile%\My Documents
%Userprofile%\Application Data , etc
HKEY_CURRENT_USER\Software\Microsoft\WAB\WAB4\Wab File Name
and searches for emails.
go and detect the other information.
 In a difficult world
In a nameless time
I want to survive
So, you will be mine!!,second author

 Nemog and ZinCite :P¿mnopqrst

------------------- About_Mydoom.txt contents ------------------

Spreading in emails

The worm spreads by sending its infected attachment to all email addresses found on an infected computer. The worm looks for email addresses in Windows Address Book and in the files with the following extensions:

  • txt
  • htm
  • html
  • mbx
  • mdx
  • xml
  • jsp
  • xls
  • uin
  • msg
  • wsh
  • cgi
  • eml
  • cfg
  • vbs
  • sht
  • php
  • asp
  • dbx
  • tbb
  • adb
  • wab

The worm avoids sending emails to email addresses that contain any of the following substrings:

  • avp.
  • syman
  • icrosof
  • panda
  • sopho
  • borlan
  • inpris
  • example
  • mydomai
  • nodomai
  • ruslis
  • .gov
  • gov.
  • .mil
  • foo.
  • berkeley
  • unix
  • math
  • mit.e
  • gnu
  • fsf.
  • kernel
  • linux
  • fido
  • usenet
  • iana
  • ietf
  • rfc-ed
  • sendmail
  • arin.
  • ripe.
  • isi.e
  • isc.o
  • acketst
  • pgp
  • tanford.e
  • utgers.ed
  • mozilla

The subject of infected emails is selected from the following variants:

  • Re:Help
  • FW:Hi'
  • Hello'
  • Re:Test
  • Delivery status Notification
  • Important
  • Re:Important
  • FW:Important
  • Information
  • FW:Information
  • Re:Information
  • Read
  • FW:Read
  • Re:Read
  • Re:Question
  • Re:Hi
  • Hi!
  • News
  • Re:News
  • Thanks
  • Re:Thanks
  • FW:Thanks
  • Re:Hello!
  • Hello
  • Hello!
  • FW:Hello

The body text of infected emails is selected from the following variants:

  • test
  • Please read the important document.
  • I have attached document.
  • Waiting for a Response. Please read the attachment.
  • Thanks!
  • Please see the attached file for details
  • Please read the attached file!
  • Please confirm!
  • Please answer quickly!
  • For more details see the attachment.
  • For further details see the attachment.
  • Monthly news report.
  • Virus removal tool
  • apply this patch!
  • fun game!
  • lol!
  • fun!
  • See the file.
  • screensaverlol!
  • See the file.
  • Your archive is attached.
  • check!
  • Error
  • !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  • Hello Check the attachment.
  • Here is the attachment.
  • :-)
  • Here is my photo.:-)
  • +++ Attachment: No Virus found
  • +++ Attachment: No Infection found
  • Norton AntiVirus -
  • F-Secure AntiVirus -
  • Norman AntiVirus -
  • Panda AntiVirus -
  • Kaspersky AntiVirus -
  • MC-Afee AntiVirus -
  • Bitdefender AntiVirus -
  • MessageLabs AntiVirus -

The worm can send itself as an executable attachment or in a ZIP archive with one of the following names:

  • Virus
  • XXX Pictures
  • XXX Videos
  • xbox emulator
  • ps2 emulator
  • Hotmail hacker
  • yahoo hacker
  • klez
  • SoBig
  • mydoom
  • netsky
  • Upload
  • crack
  • Winzip
  • kazz
  • Winrar
  • mirc
  • pyrnare
  • SeX
  • Vaho
  • Fixtool
  • Winamp

with any of the following extensions appended:

  • .exe
  • .scr
  • .pif
  • .bat
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