Threat Description

Backdoor: W32/Bugbear.K


Category: Malware
Type: BackdoorNet-Worm
Platform: W32
Date Discovered: April 12, 2006
Aliases: Backdoor:W32/Bugbear.K, Email-Worm.Win32.Tanatos.k, Email-Worm:W32/Bugbear.K


A remote administration utility which bypasses normal security mechanisms to secretly control a program, computer or network.


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 scanning or removal options is available in the documentation for your F-Secure security product on the Downloads section of our Home - Global site.

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:


After disinfection it is recommended to change all log-in credentials, as they could have been compromised by the password stealer component of the worm. It is also recommended to check infected systems and networks for possible hacker intrusion that could have been performed through the backdoor component of the worm.

More details about the removing procedure you can find in our support center:

Technical Details

Backdoor:W32/Bugbear.K (also known as Tanatos) is an e-mail and network worm that also has a backdoor component. This particular variant is very similar to the original Tanatos worm that was found in 2002.


This Tanatos worm variant spreads in e-mail messages with the following characteristics:


  • !!! WARNING !!!
  • ;)
  • [Fwd: look] ;-)
  • Announcement
  • bad news
  • empty account
  • fantastic
  • Friendly
  • Fwd:
  • good news!
  • Greetings!
  • Greets!
  • Hello!
  • Hi!
  • history screen
  • hmm.."
  • I cannot forget you!
  • I love you!
  • I need photo!!!
  • Interesting...
  • Introduction
  • Is that your password?
  • Just a reminder
  • look
  • Lost & Found
  • Love
  • Me nude
  • New Contests
  • new reading
  • News
  • Old photos
  • Payment notices
  • photo
  • photos
  • Please Help...
  • Re:
  • Report
  • Sex pictures
  • sexy
  • Stats
  • Today Only
  • update
  • various
  • Warning!
  • wow!
  • You are fat!
  • Your Gift

Body text:

  • Pease open an attachment to see the message.
  • Please see Attachment
  • please,read the attach file.
  • see attachment
  • See the attached file
  • See the attached file for more info
  • Take a look to the attachment

Attachment names:

  • a000032.jpg [lots of spaces] .scr
  • girls.jpg [lots of spaces] .scr
  • image.jpg [lots of spaces] .scr
  • love.jpg [lots of spaces] .scr
  • message.txt [lots of spaces] .scr
  • music.mp3 [lots of spaces] .scr
  • myphoto.jpg [lots of spaces] .scr
  • news.doc [lots of spaces] .scr
  • photo.jpg [lots of spaces] .scr
  • pic.jpg [lots of spaces] .scr
  • readme.txt [lots of spaces] .scr
  • song.wav [lots of spaces] .scr
  • video.avi [lots of spaces] .scr
  • you.jpg [lots of spaces] .scr


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