Skip to main content
Published May 21, 2007 | Updated Sep 15, 2017

Trojan:Win32/VB.KB

Detected by Microsoft Defender Antivirus

Aliases: No associated aliases

Summary

Trojan:Win32/VB.KB drops files to the Windows folder, modifies the registry to load these files when Windows is started, and sends an HTTP GET request to a remote Web site.
To recover manually from infection by Trojan:Win32/VB.KB, perform the following steps:
  • Disconnect from the Internet.
  • Restart the computer in safe mode.
  • End the Trojan process.
  • Delete the Trojan files from your computer.
  • Delete the Trojan registry entries.
  • Restart the computer. 
  • Take steps to prevent re-infection.

Disconnect from the Internet

To help ensure that your computer is not actively infecting other computers, disconnect it from the Internet before proceeding. Print this Web page or save a copy on your computer; then unplug your network cable and disable your wireless connection. You can reconnect to the Internet after completing these steps.

Restart the computer in safe mode

To start your computer in safe mode
  1. Remove all floppy disks and CDs from your computer, and then restart your computer.
  2. When prompted, press F8. If Windows starts without displaying the Please select the operating system to start menu, restart your computer. Press F8 after the firmware POST process completes, but before Windows displays graphical output.
  3. From the Windows Advanced Options Menu, select a safe mode option.

End the Trojan process

Ending the Trojan process will help stop your computer from infecting other computers and resolve the crashing, rebooting, and performance degradation issues caused by the Trojan.
To end the Trojan process
  1. Press CTRL+ALT+DEL once and click Task Manager. 
  2. Click Processes and click Image Name to sort the running processes by name.
  3. Select each Trojan process (a1.exe, s1.exe, d1.exe and f1.exe) and click End Process individually.

Delete the Trojan files from your computer

To delete the Trojan files from your computer
  1. Click Start, and click Run.
  2. In the Open field, type %windir%
  3. Click OK.
  4. Click Name to sort files by name.
  5. Delete each of the files associated with the Trojan (cfreer.exe, nzil.exe, negdo.exe and juegs.exe) from the <Windows folder>
  6. On the Desktop, right-click the Recycle Bin and click Empty Recycle Bin.
  7. Click Yes to confirm the deletion.
If deleting the file fails, use the following steps to verify that the file is not running:
  1. Press CTRL+ALT+DEL once and click Task Manager.
  2. Click Processes and click Image Name to sort the running processes by name.
  3. Confirm that all of the files 'a1.exe', 's1.exe', 'd1.exe' and 'f1.exe' are not in the list:

Delete the Trojan registry entry

To delete the Trojan registry entry
  1. On the Start menu, click Run.
  2. Type regedit and click OK.
  3. In the left pane, navigate to the key:
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, right-click the following values, if they exist:
    WindowsK = %windir%\a1.exe
    WindowsD = %windir%\s1.exe
    SysteZ = %windir%\d1.exe
  5. Click Delete and click Yes to delete the value.
  6. Close the Registry Editor.

Restart the computer

To restart your computer
  1. On the Start menu, click Shut Down.
  2. Select Restart from the drop-down list and click OK.

Take steps to prevent re-infection

You should not reconnect your computer to the Internet until the computer is protected from re-infection. See the "Preventing Infection" section for more information.
Follow us