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 security response

W32.ExploreZip.Worm Removal Tool

Discovered on: April 8, 2003
Last Updated on: July 1, 2003 12:24:14 PM PDT

Symantec Security Response has developed a removal tool to clean the infections that Worm.ExploreZip and its variants made. This tool cleans the infections of the variants up to and including W32.ExploreZip.L.Worm.

What the tool does

The W32.ExploreZip.Worm Removal Tool does the following:

  1. Terminates the Worm.ExploreZip viral processes.
  2. Deletes the Worm.ExploreZip files.
  3. Deletes the registry values that the worm added.
  4. Removes the win.ini entry that the worm added.

Command-line switches available with this tool


Switch
Description

/HELP, /H, /?
Displays the help message.

/NOFIXREG
Disables registry repair. (We do not recommend using this switch.)

/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, FixExzip.log, within the same folder from which the removal tool was executed.

/MAPPED
Scans the mapped network drives. (We do not recommend using this switch. Refer to the Notes below.)

/START
Forces the tool to immediately start scanning.

/EXCLUDE=<path>
Excludes the specified <path> from scanning. (We do not recommend using this switch.)

NOTE: Using the /MAPPED switch does not ensure the complete removal of the virus on the remote computer, because:
  • Scanning the mapped drives scans the mapped folders only. This action may not include all the folders on the remote computer, leading to missed detections.
  • If a viral file is detected on the mapped drive, the removal will fail if a program on the remote computer uses this file.

For these reasons, run the tool on every computer.

Obtaining and running the tool

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

    http://securityresponse.symantec.com/avcenter/FixExzip.exe
  2. 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).
  3. To check the authenticity of the digital signature, refer to the section, "Digital signature."
  4. Close all the running programs before running the tool.
  5. 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.
  6. If you are running Windows Me or XP, then disable System Restore. 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.
  7. Double-click the FixExzip.exe file to start the removal tool.
  8. Click Start to begin the process, and then allow the tool to run.
  9. Restart the computer.
  10. Run the removal tool again to ensure that the system is clean.
  11. If you are running Windows Me/XP, then re-enable System Restore.
  12. Run LiveUpdate to make sure that you are using the most current virus definitions.

NOTE: The removal procedure may be unsuccessful if Windows Me/XP System Restore is not disabled as previously directed, because Windows prevents outside programs from modifying System Restore.

When the tool has finished running, you will see a message indicating whether W32.HLLW.Nebiwo infected the computer. In the case of a worm removal, the program displays the following results:
  • Total number of the scanned files.
  • Number of deleted files.
  • Number of terminated viral processes.
  • Number of fixed registry entries.

Digital signature
FixExzip.exe is digitally signed. Symantec recommends that you only use copies of FixExzip.exe that have been directly downloaded from the Symantec Security Response Web site. To check the authenticity of the digital signature, follow these steps:
  1. Go to http://www.wmsoftware.com/free.htm.

  2. Download and save the chktrust.exe file to the same folder where you saved FixExzip.exe (for example, C:\Downloads).

  3. 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.


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

    chktrust -i FixExzip.exe

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

    cd\
    cd downloads
    chktrust -i FixExzip.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 "ExploreZip Removal Tool" signed on 4/8/2003 12:26 PM and distributed by Symantec Corporation?

    NOTES    :
    • The date and time 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 displayed time 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, do 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."

  5. Click Yes to close the dialog box.

  6. Type exit, and then press Enter. This will close the MS-DOS session.

System Restore option in Windows Me/XP
Users of Windows Me and Windows XP should temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file onto your computer, even after you have cleaned the infected files from all the other locations.

Also, in some cases, online scanners may detect a threat in the System Restore folder even though you scanned your computer with an antivirus program and did not find any infected files.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
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
  1. Insert the floppy disk, which contains the FixExzip.exe file, in the floppy disk drive.
  2. Click Start, and then click Run.
  3. Type the following:

    a:\fixexzip.exe

    and then click OK:

    NOTES:
    • There are no spaces in the command, a:\fixexzip.exe.
    • If you are using Windows Me and 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.
  4. Click Start to begin the process, and then allow the tool to run.
  5. If you are using Windows Me, then re-enable System Restore.