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Published Jun 27, 2005 | Updated Sep 15, 2017

TrojanDropper:Win32/Bagle.BS

Detected by Microsoft Defender Antivirus

Aliases: W32/Bagle.dldr.gen (McAfee) Trojan.Tooso.J (Symantec)

Summary

TrojanDropper:Win32/Bagle.BS is a Trojan that targets computers running certain versions of Microsoft Windows. The Trojan drops a dynamic-link library (DLL) file that can download and run malicious files from certain Web sites.
To manually recover from infection by TrojanDropper:Win32/Bagle.BS, perform the following steps:
  • Disconnect from the Internet.
  • Restart the computer in safe mode.
  • End the Trojan process.
  • Delete the Trojan executable file from your computer.
  • Delete the Trojan registry entries.
  • Restart the computer. 
  • Delete the Trojan DLL file from your 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 worm.
To end the worm 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 the process winshost.exe and click End Process.

Delete the Trojan executable file from your computer

To delete the Trojan file from your computer
  1. Click Start, and click Run.
  2. In the Open field, type the name of the system folder, for example, C:\Windows\System32.
  3. Click OK.
  4. Click Name to sort files by name.
  5. If winshost.exe is in the list, delete it.
  6. On the Desktop, right-click the Recycle Bin and click Empty Recycle Bin.
  7. Click Yes.

Delete the Trojan registry entries

To delete the Trojan registry entries
  1. On the Start menu, click Run.
  2. Type regedit and click OK.
  3. In the left pane, navigate to the key:
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, right-click the following value, if it exists: winshost.exe  
  5. Click Delete and click Yes to delete the value.
  6. Repeat steps 3 through 5 for the following registry key:
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  7. 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.

Delete the Trojan DLL file from your computer

To delete the Trojan DLL file from your computer
  1. Click Start, and click Run.
  2. In the Open field, type the name of the system folder, for example, C:\windows\system32.
  3. Click OK.
  4. Click Name to sort files by name.
  5. If wiwshost.exe is in the list, delete it.
  6. On the Desktop, right-click the Recycle Bin and click Empty Recycle Bin.
  7. Click Yes.

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.
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