Threat description




A new UPX packed variant of MyDoom worm - Mydoom.Q, was found on August 3rd, 2004. The worm spreads like its previous variants and it also uses Yahoo People Search to search for more victims' e-mail addresses.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More scanning & removal options

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Eliminating a Local Network Outbreak

If the infection is in a local network, please follow the instructions on this webpage:

Technical Details

The worm's file is a PE executable 21504 bytes long packed with UPX file compressor. The unpacked worm's size is about 62 kilobytes.

System Infection

After the worm's file is run, it opens Notepad application. Then the worm copies itself as WINLIBS.EXE file to Windows System directory and creates a startup key for the copied file in Windows Registry:

  • [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run] "winlibs.exe" = "%WinSysDir%\winlibs.exe"

where %WinSysDir% represents Windows System folder. As a result, the worm's file is started every time Windows starts.

Additionally the worm creates the following Registry key:

  • [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\winlibs]

The worm creates a mutex named 'NorthernLightMixed'.

Spreading in e-mails

The worm spreads in e-mails. Before spreading it collects e-mail addresses from an infected computer. The worm reads Windows Address Book file, reads files in Temporary Internet Files folders and Windows System folder. Files with the following extensions are checked:

  • txt
  • dhtm
  • msg
  • htm
  • xml
  • eml
  • html
  • sht
  • shtm
  • shtml
  • jse
  • jsp
  • js
  • php
  • cfg
  • asp
  • ods
  • mmf
  • dbx
  • tbb
  • adb
  • pl
  • wab

Additionally the worm can connect to '' server and tries to search for victims' e-mail addresses there.

The worm doesn't send itself to e-mail addresses that contain any of the following substrings:

  • .edu
  • Bug
  • ugs
  • bug
  • upport
  • icrosoft
  • oot
  • dmin
  • ymant
  • avp
  • ecur
  • @MM
  • ebmast
  • help
  • opho
  • inpris
  • omain
  • senet
  • panda
  • 32.
  • @mm
  • msn
  • inux
  • umit
  • nfo
  • irus
  • buse
  • orton
  • cafee
  • spam
  • Spam
  • SPAM
  • ntivi
  • eport
  • user
  • inzip
  • inrar
  • rend
  • pdate
  • USER
  • ating
  • ample
  • ists
  • persk
  • ccoun
  • ompu
  • msdn
  • YOU
  • you
  • oogle
  • arsoft
  • otmail
  • sarc
  • soft
  • ware
  • .gov
  • .mil
  • cribe
  • list
  • eturn
  • omment
  • Sale
  • sale
  • gmail
  • ruslis
  • ibm
  • win
  • !

The worm spreads in e-mails with different subject and body texts and with different attachment names. The subject line is selected from the following variants:

  • SN: New secure mail
  • Secure delivery
  • failed transaction
  • Re: hello (Secure-Mail)
  • Re: Extended Mail
  • Delivery Status (Secure)
  • Re: Server Reply
  • SN: Server Status

The message body can contain user name, domain name and the following text strings:

  • Automatically Secure Delivery: for
  • Mail Delivery Server System: for
  • Extended secure mail message available at:
  • Secure Mail Server Notification: for
  • New mail secure method implement: for
  • New policy requested by mail server to returned mail as a secure compiled attachment (Zip).
  • Now a new message is available as secure Zip file format. Due to new policies on clients.
  • This message is available as a secure Zip file format due to a new security policy.
  • For security measures this message has been packed as Zip format. This is a newly added security feature.
  • New policy recommends to enclose all messages as Zip format. Your message is available in this server notice.
  • You have received a message that implements secure delivery technology. Message available as a secure Zip file.
  • This message is an automatically server notice from Administration at
  • Server Notice: New security feature added. MSG:ID: 455sec86
  • from
  • New feature added for security reasons from
  • Automatically server notice:,
  • Server reply from
  • New service policy for security added from

The attachment name is selected from the following variants:

  • mail
  • message
  • attachment
  • transcript
  • text
  • document
  • file
  • readme

The attachment extension is selected from these variants:

  • .exe
  • -txt.exe
  • -htm.exe
  • -txt.scr

Also the worm can send itself inside a ZIP archive.

The worm fakes the sender's e-mail address. It uses the following user names for the fake e-mail address:

  • mike@
  • jennifer@
  • david@
  • linda@
  • susan@
  • nancy@
  • pamela@
  • eric@
  • kevin@
  • mary@
  • jessica@
  • patricia@
  • barbara@
  • karen@
  • sarah@
  • robert@
  • john@
  • daniel@
  • jason@
  • joe@

In the very beginning of its execution the worm creates a thread that enumerates processes and terminates the ones that have the following substrings in their names:

  • uba
  • mc
  • Mc
  • av
  • AV
  • cc
  • Sym
  • nv
  • can
  • scn
  • java
  • xp.exe
  • ecur
  • nti
  • erve
  • sss
  • iru
  • ort
  • SkyNet
  • KV

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