Trojan-Ransom.Win32.DigiPog.xp

Technical Details

This Trojan disables a machine in order to obtain a ransom for restoring the system to its original condition. It is a Windows application (PE EXE file). It is 151 040 bytes in size. It is written in C++.

Installation

Once launched, the Trojan performs the following actions:

• It attempts to unload the following processes from the system memory:

  Tmas.exe
  ekrn.exe
  gcasServ.exe
  msscli.exe
  avp.exe
  dwengine.exe
  avastsvc.exe
  avguard.exe
  winroute.exe
  zlclient.exe
  op_mon.exe
  

• It stops the "SharedAccess" service.
• It attempts to call the "__register_frame_info" and "_Jv_RegisterClasses" functions from the following libraries, respectively:

  %WorkDir%\libgcc_s_dw2-1.dll
  %WorkDir%\libgcj_s.dll
  

• It creates the following file to flag its presence in the system:

  %USERPROFILE%\Application Data\efhhcwck.ddr (1598 bytes)
  

  It also creates the following system registry key:

  [HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform]
  "0X29A"
  

• It copies itself to the following file:

  %USERPROFILE%\Application Data\efhhcwck.exe

• To ensure that the copy created is launched automatically each time the system is rebooted, the following system registry keys are created:

  [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
  "PC Health Status" = "%USERPROFILE%\Application Data\efhhcwck.exe"
  
  [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
  "PC Health Status" = "%USERPROFILE%\Application Data\efhhcwck.exe"
  

  It also creates the shortcut:

  %USERPROFILE%\Start Menu\Programs\Startup\healm_jamc.lnk
  

  This shortcut points to the created copy.
• It launches the copy created for execution. This copy is launched twice: initially it is launched without any parameters, and the second time it is launched with the "DNNL" parameter. There always will be two copies of the "efhhcwck.exe" process launched in the system. If one of the processes ceases running, it will be relaunched by the second process.
• During installation the Trojan displays the following windows:
  
  
  
• In addition, the Trojan sends to the malicious user's server:

  188.***.168

  the following HTTP requests:

  HTTP/1.0
  GET
  /_req/?type=e&sid=2&sw=00000000000000000&ostype=2&ossp=2&osbits=0&osfwtype=2&osrights=255
  /_req/?type=m&sid=2&sw=00000000000000000
  

  
  

  Payload

  Once launched, the Trojan performs the following actions:
  1. It deletes its original file by reading the path from the following file:

     %USERPROFILE%\Application Data\efhhcwck.ddr

  2. To ensure that its process is unique within the system, it creates a unique identifier:

     Global\dobeDNNLjpgo

  3. It creates the following system registry keys:

     [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System]
     "DisableTaskMgr" = "1"
     
     [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
     "NoLogoff" = "1"
     

     Thereby it stops the Task Manager from launching, and hides the "Shut down" sub-menu in the Start menu.
  4. It blocks Internet Explorer's access to the Internet by changing its proxy server settings:

     [HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
     "MigrateProxy" = "1"
     "ProxyEnable" = "1"
     "ProxyServer" = "http=127.0.0.1:41653;"
     

     At the same time, it deletes the following keys:

     [HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
     "ProxyOverride"
     "AutoConfigURL"
     

     These keys are created and deleted in an endless cycle.
  5. When the user runs other browsers, the Trojan blocks the following sites:

     www.drweb.com/unlocker
     www.esetnod32.ru/.support/winlock
     http://virusinfo.info/deblocker
     http://support.kaspersky.ru/viruses/deblocker
     

  6. It terminates the following processes in an endless cycle:

     far.exe
     msconfig.exe
     taskmgr.exe
     taskkill.exe
     avz.exe
     regedit.exe
     procmon.exe
     

  7. It displays the following window over the top of all open windows in the lower right corner of the screen:
     
  8. It sends to the malicious user's server

     188.***.168

     the following request:

     HTTP/1.0
     GET
     _req/?type=s&sid=2&sw=00000000000000001&ostype=2&ossp=2&osbits=0&osfwtype=2&osrights=255
     

  
  

  Removal instructions

  If your computer does not have antivirus protection and has been infected by this malicious program, follow the instructions below to delete it:
  1. Reboot the computer in Safe Mode (at the start of the boot sequence, press and hold F8, then choose Safe Mode from the Windows boot menu).
  2. Delete the following files:

     %USERPROFILE%\Application Data\efhhcwck.ddr 
     %USERPROFILE%\Application Data\efhhcwck.exe
     %USERPROFILE%\Start Menu\Programs\Startup\healm_jamc.lnk
     

  3. Delete the following system registry keys (see What is a system registry and how do I use it?):

     [HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform]
     "0X29A"
     
     [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
     "PC Health Status" = "%USERPROFILE%\Application Data\efhhcwck.exe"
     
     [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
     "PC Health Status" = "%USERPROFILE%\Application Data\efhhcwck.exe"
     
     [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System]
     "DisableTaskMgr" = "1"
     
     [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
     "NoLogoff" = "1"
     

  4. Restore the original system registry key value (What is a system registry and how do I use it?):

     [HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
     "MigrateProxy"
     "ProxyEnable"
     "ProxyServer"
     "ProxyOverride"
     "AutoConfigURL"