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TrojanDownloader:Win32/Bredolab.G


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


What to do now

Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as the Microsoft Safety Scanner (http://go.microsoft.com/fwlink/?LinkId=212742). For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.

Threat behavior

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>\wbem\grpconv.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:\Winnt\System32; and for XP and Vista is C:\Windows\System32.
 
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: HKCU\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
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 malware
TrojanDownloader: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

Symptoms

System Changes
The following system changes may indicate the presence of this malware:
  • The presence of the following file:
    <system folder>\wbem\grpconv.exe
  • The presence of the following registry modification:
    Added value: "RunGrpConv"
    With data: "0x00000001"
    To subkey: HKCU\Software\Microsoft\Windows NT\CurrentVersion\Winlogon

Prevention


Alert level: Severe
First detected by definition: 1.61.389.0
Latest detected by definition: 1.203.1472.0 and higher
First detected on: Jun 25, 2009
This entry was first published on: May 28, 2009
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • Win32/Bredolab.HW (CA)
  • Troj/Dloadr-CMT (Sophos)
  • Spy-Agent.bw (McAfee)
  • Win32/TrojanDownloader.Bredolab.AA (ESET)