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Published Feb 24, 2005 | Updated Sep 15, 2017

Worm:Win32/Bagle.BF@mm

Detected by Microsoft Defender Antivirus

Aliases: W32/Bagle.bl@MM (McAfee) WORM_BAGLE.BA (Trend Micro) Win32.Bagle.AV!Worm (CA)

Summary

Win32/Bagle.BF@mm is a mass-mailing worm that targets certain versions of Microsoft Windows. The worm sends itself as an attachment to e-mail addresses that it finds on the infected computer. The worm is activated when a user opens the attachment. The worm monitors a random TCP port for instructions from remote attackers.
To manually recover from infection by Win32/Bagle.BF@mm, perform the following steps:
  1. Disconnect from the Internet.
  2. Restart your computer in safe mode.
  3. End the worm process.
  4. Delete the worm files from your computer.
  5. Delete the worm registry entry.
  6. Restart your computer.
  7. 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 your 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 worm process

Ending the worm process will help stop your computer from infecting other computers as well as 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 sysformat.exe, and click End Process.

Delete the worm files from your computer

To delete the worm files from your computer
  1. Click Start, and click Run.
  2. In the Open field, type %Windir%\system32
  3. Click OK.
  4. Click Name to sort files by name.
  5. If sysformat.exe is in the list, delete it.
  6. On the Desktop, right-click the Recycle Bin and click Empty Recycle Bin.
  7. Click Yes.
If deleting files fails, use the following steps to verify that sysformat.exe 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 sysformat.exe is not in the list.

Delete the worm registry entry

To delete the worm 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
    In the right pane, right-click the following value, if it exists: 
    sysformat = <system folder>\sysformat.exe
  4. Click Delete and click Yes to delete the value.
  5. Close the Registry Editor.

Restart your 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

Do not reconnect the computer to the Internet until the computer is protected from re-infection. See the "Preventing Infection" section for more information.
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