W32.Frethem Removal Tool

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Discovered: July 16, 2002
Updated: January 31, 2006 12:00:00 AM
Type: Removal Information

Symantec Security Response has created a fixtool to repair infections of all known W32.Frethem variants. This includes W32.Frethem.A@mm through W32.Frethem.O@mm.

What the tool does

The W32.Frethem.Gen@mm Removal Tool does the following:
It terminates all the known W32.Frethem viral processes.
It deletes all the known W32.Frethem files.
It deletes the registry value added by the worm.
Command-line switches available with this tool

Switch Description
/HELP, /H, /? Displays the help message.
/NOFIXREG Disables registry repair (the use of this switch is not recommended).
/SILENT, /S Enables silent mode.
/LOG=[PATH NAME] Creates a log file where [PATH NAME] is the location in which to store the tool's output. By default, this switch creates the log file FixFreth.log in the same folder from which the removal tool was executed.
/MAPPED Scans mapped network drives (the use of this switch is not recommended--see notes).
/START Forces the tool to start scanning immediately.
/EXCLUDE=[PATH] Excludes the specified [PATH] from scanning (the use of this switch is not recommended).

NOTE: The use of the /MAPPED switch does not ensure the complete removal of the virus on the remote computer because:
The scanning of mapped drives scans only the folders that are mapped. This might not include all folders on the remote computer, and this can to lead to missed detections.
If a viral file is detected on the mapped drive, the removal will fail if a program on the remote computer is using this file.

For these reasons, you should run the tool on every computer.

To obtain and run the tool

NOTE: You must have administrative rights to run this tool on Windows NT 4.0, Windows 2000, or Windows XP.
Download the FixFreth.exe file from:


Save the file to a convenient location, such as your downloads folder or the Windows desktop (or removable media that is known to be uninfected, if possible).
To check the authenticity of the digital signature, refer to the section The digital signature.
Close all running programs before running the tool.
If you are on a network or you have a full-time connection to the Internet, disconnect the computer from the network and the Internet.
If you are running Windows Me or XP, then disable System Restore. Please refer to the section System Restore option in Windows Me/XP for additional details.

CAUTION: If you are running Windows Me/XP, we strongly recommend that you do not skip this step.

Double-click the FixFreth.exe file to start the removal tool.
Click Start to begin the process, and then allow the tool to run.
Restart the computer.
Run the removal tool again to ensure that the system is clean.
If you are running Windows Me/XP, then re-enable System Restore.
Run LiveUpdate to make sure that you are using the most current virus definitions.

NOTE: The removal procedure might be unsuccessful if Windows Me/XP System Restore is not disabled as previously directed because Windows prevents System Restore from being modified by outside programs. Because of this, the removal tool might fail.

When the tool has finished running, you will see a message indicating whether the computer was infected by W32.Frethem.Gen@mm. In the case of a removal of the worm, the program displays the following results:
The total number of the scanned files.
The number of deleted files.
The number of viral processes terminated.
The number of registry entries fixed.

The digital signature
FixFreth.exe is digitally signed. Symantec recommends that you only use copies of FixFreth.exe that have been downloaded directly from the Symantec Security Response download site. To check the authenticity of the digital signature, follow these steps:
Go to http://www.wmsoftware.com/free.htm
Download and save the chktrust.exe file to the same folder where you saved FixFreth.exe (for example, C:\Downloads).
Depending on your operating system, do one of the following:
Click Start, point to Programs, and click MS-DOS Prompt.
Click Start, point to Programs, click Accessories, and then click Command Prompt.

Change to the folder where FixFreth.exe and Chktrust.exe are stored, and then type:

chktrust -i FixFreth.exe

For example, if you saved the file to the C:\Downloads folder, you would enter the following commands:

cdcd downloads
chktrust -i FixFreth.exe

Press Enter after typing each command. If the digital signature is valid, you will see the following:

Do you want to install and run "FixFreth.exe" signed on 4/8/2003 1:33 PM and distributed by Symantec Corporation.

The date and time that are displayed in this dialog box will be adjusted to your time zone if your computer is not set to the Pacific time zone.
If you are using Daylight Saving time, the time that is displayed will be exactly one hour earlier.
If this dialog box does not appear, there are two possible reasons:
The tool is not from Symantec. Unless you are sure that the tool is legitimate, and that you downloaded it from the legitimate Symantec Web site, you should not run it.
The tool is from Symantec, and is legitimate. However, your operating System was previously instructed to always trust content from Symantec. For information on this, and how to view the confirmation dialog again, read the document How to restore the Publisher Authenticity confirmation dialog box.
Click Yes to close the dialog box.
Type exit and then press Enter. This will close the MS-DOS session.

System Restore option in Windows Me/XP
Windows Me and Windows XP users should temporarily turn off System Restore. This feature, which is enabled by default, is used by Windows Me/XP to restore files on your computer in case they become damaged. When a computer is infected with a virus, worm, or Trojan, it is possible that the virus, worm, or Trojan could be backed up by System Restore. By default, Windows prevents System Restore from being modified by outside programs. As a result, there is the possibility that you could accidentally restore an infected file, or that on-line scanners would detect the threat in that location. For instructions on how to turn off System Restore, read your Windows documentation or one of the following articles:
How to disable or enable Windows Me System Restore.
How to disable or enable Windows XP System Restore.

For additional information, and an alternative to disabling Windows Me System Restore, read the Microsoft Knowledge Base article Antivirus Tools Cannot Clean Infected Files in the _Restore Folder (Q263455).

How to run the tool from a floppy disk
Insert the floppy disk that contains the FixFreth.exe file in the floppy disk drive.
Click Start and then click Run.
Type the following and then click OK:


There are no spaces in the command a:\fixfreth.exe.
If you are using Windows Me, and the System Restore remains enabled, you will see a warning message. You can choose to run the removal tool with the System Restore option enabled or exit the removal tool.

Click Start to begin the process, and then allow the tool to run.
If you are using Windows Me, then reenable System Restore.