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TrojanDownloader:Win32/Bredolab.G


First posted on 12 June 2009.
Source: SecurityHome

Aliases :

TrojanDownloader:Win32/Bredolab.G is also known as Also Known As:Win32/Bredolab.HW (CA), Troj/Dloadr-CMT (Sophos), Spy-Agent.bw (McAfee), Win32/TrojanDownloader.Bredolab.AA (ESET).

Explanation :

TrojanDownloader:Win32/Bredolab.G is a detection of malware that connects to a remote server to download and execute files.

Symptoms
System ChangesThe following system changes may indicate the presence of this malware:

  • The presence of the following file:
    <system folder>wbemgrpconv.exe
  • The presence of the following registry modification:
    Added value: "RunGrpConv"
    With data: "0x00000001"
    To subkey: HKCUSoftwareMicrosoftWindows NTCurrentVersionWinlogon


    • TrojanDownloader:Win32/Bredolab.G is a detection of malware that connects to a remote server to download and execute files.

    Installation
    Upon execution, TrojanDownloader:Win32/Bredolab.G injects itself into the running 'explorer.exe' process. It also launches 'svchost.exe' and injects itself in that process. It copies itself into the system as the following:
  • <system folder>wbemgrpconv.exe
    • Note - <system folder> refers to a variable location that is determined by the malware by querying the Operating System. The default installation location for the System folder for Windows 2000 and NT is C:WinntSystem32; and for XP and Vista is C:WindowsSystem32. It creates the following registry entry to ensure that its dropped copy runs every time Windows starts: Adds value: "RunGrpConv"
    With data: "0x00000001"
    To subkey: HKCUSoftwareMicrosoftWindows NTCurrentVersionWinlogon

    Payload
    Disables system security processes TrojanDownloader:Win32/Bredolab.G attempts to disable the following system security processes:
  • HIPS (Host Intrusion Prevention System) - if it exists in the system
  • Windows SFC (System File Checker) - <system folder>sfc.exe
    • Downloads other malwareTrojanDownloader:Win32/Bredolab.G attempts to connect to a remote IP address to report successful infection of the system and to download other malware. For example, one sample connect to the following address to download members of the Momibot and the Waledac families.

    Analysis by Shawn Wang

    Last update 12 June 2009

     

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