Threat Description

Trojan-Downloader: W32/Bredolab


Category: Malware
Type: Trojan-Downloader
Platform: W32
Aliases: Trojan-Downloader:W32/Bredolab, Trojan-Downloader:W32/Bredolab, Trojan-downloader:w32/bredolab.gen!c


This type of trojan secretly downloads malicious files from a remote server, then installs and executes the files.


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 more information.

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details

Trojan-Downloader:W32/Bredolab is a family of trojan-downloaders that are known to download and install rogue antivirus programs - also known as rogueware - onto the infected computer. The installed rogueware generates misleading or downright false alerts, notification messages and/or scanning reports to pressure the user into "purchasing" or "activating" the rogueware in order to disinfect or remove the supposed threats. Even if the user does so however, the program may not function as intended.


During installation, Bredolab variants create the following registry entry so that the trojan-downloader runs every time Windows starts:

HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\ "RunGrpConv" = "1"   

It also creates the following mutex so that only one instance of the downloader will be running on the system:

  • _SYSTEM_4D2EF3A_

Currently, all the variants analyzed were found to download files from Russian websites such as those listed below:

  • http://mud[...].ru
  • http://davidbred[...].ru

The files downloaded from those websites are encrypted and will be decrypted by the trojan-downloader before being executed on the infected machine.


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