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Discovered: July 14, 2003
Updated: February 13, 2007 12:03:52 PM
Also Known As: W32/MoFei.worm [McAfee], WORM_MOFEI.D [Trend], W32/Mofei-B [Sophos], Worm.Win32.Mofeir.c [KAV]
Type: Worm
Systems Affected: Windows

The W32.Femot.D.Worm worm:

  • Is a network-aware
  • Has backdoor capabilities
  • Is compressed with ASPack

The existence of the file Lasvr32.exe is an indication of a possible infection.

Antivirus Protection Dates

  • Initial Rapid Release version July 14, 2003
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version July 14, 2003
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date July 16, 2003

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Yana Liu

Discovered: July 14, 2003
Updated: February 13, 2007 12:03:52 PM
Also Known As: W32/MoFei.worm [McAfee], WORM_MOFEI.D [Trend], W32/Mofei-B [Sophos], Worm.Win32.Mofeir.c [KAV]
Type: Worm
Systems Affected: Windows

When W32.Femot.D.Worm runs, it does the following:

  1. Copies itself as %Windir%\System32\Lasvr32.exe.

    NOTE: %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to the System32 subfolder under that location.

  2. Creates the following files:
    • %Windir%\System32\Lasvr32.dll (45,056 bytes)
    • %Windir%\System32\MoFei.cfg.

  3. On Windows 2000/NT/XP, it adds the service, "Smart Card Helper," and sets it to run the %Windir%\System32\Lasvr32.exe file.

    The Smart Card Helper service is installed on some version of Windows by default. If it is already installed, the worm attempts to replace the service with itself.

  4. On Windows 2000/NT/XP, it injects its code to the LSASS.EXE and IEXPLORE.EXE processes.

  5. On Windows 95/98/Me, it adds the value:

    "NavAgent32"="%Windir%\System32\lasvr32.exe" -v

    to the registry key:


    so that the worm runs when you start Windows.

  6. On Windows 95/98/Me, it also creates the following files:
    • %Windir%\System32\Navpw32.exe (15,360 bytes), which is the backdoor component of the worm.
    • %Windir%\System32\MoFei.id.
    • %Windir%\System32\MoFei.mis.

      Then the worm runs Navpw32.exe as a service.

  7. Connects to the following Web sites by TCP port 8080 or 1080:
    • google.ods.org
    • windowsupdate.daemon.sh

Worm routine on Windows NT/2000/XP
The worm routine works only on Windows NT/2000/XP. The worm attempts to connect to other computers as either the current user or as Administrator.
It uses the following passwords:
  • stgzs
  • security
  • super
  • oracle
  • secret
  • root
  • admin
  • password
  • passwd
  • pass
  • 88888888
  • 888888
  • 00000000
  • 000000
  • 11111111
  • 111111
  • 111
  • fan@ing*
  • 54321
  • 654321
  • 12345678
  • 1234567
  • 123456
  • 12345
  • 1234
  • 123
  • 12

If the worm successfully connects, it checks for the existence of the following files:
  • %s\ADMIN$\System32\lasvr32.exe
  • %s\ADMIN$\System32\MoFei.ver

If the files are not on the computer, it attempts to create the following files:
  • %s\ADMIN$\System32\lasvr32.exe
  • %s\ADMIN$\System32\MoFei.ver
  • %s\IPC$\System32\lasvr32.exe
  • %s\IPC$\System32\MoFei.ver
    Then the worm adds and starts the service.
      The worm listens for the commands from its creator, who may perform any of the following actions:
      • Access the Windows command shell (Cmd.exe or Command.com)
      • Run executable files
      • Delete/create files and folders
      • Download files from the Internet


      Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

      • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
      • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
      • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
      • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
      • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
      • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
      • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
      • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
      • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
      • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
      • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
      • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
      • For further information on the terms used in this document, please refer to the Security Response glossary.

      Writeup By: Yana Liu

      Discovered: July 14, 2003
      Updated: February 13, 2007 12:03:52 PM
      Also Known As: W32/MoFei.worm [McAfee], WORM_MOFEI.D [Trend], W32/Mofei-B [Sophos], Worm.Win32.Mofeir.c [KAV]
      Type: Worm
      Systems Affected: Windows

      Removal using the W32.Femot.D.Worm Removal Tool
      Symantec Security Response has created a tool to remove W32.Femot.D.Worm, which is the easiest way to remove this threat.

      Manual Removal
      As an alternative to using the removal tool, you can manually remove this threat.

      The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

      1. Disable System Restore (Windows Me/XP).
      2. Update the virus definitions.
      3. Finding and stopping the service.
      4. Run a full system scan and delete all the files detected as W32.Femot.D.Worm. Delete MoFei.ver or MoFei.cfg if they exist.
      5. Delete the values that were added to the registry.

      For specific details on each of these steps, read the following instructions.

      1. Disabling System Restore (Windows Me/XP)
      If you are running Windows Me or Windows XP, we recommend that you 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 on your computer, even after you have cleaned the infected files from all the other locations.

      Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

      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, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder ," Article ID: Q263455.

      2. Updating the virus definitions
      Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
      • Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
      • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

        The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

      3. Finding and stopping the service
      1. Click Start, and then click Run.
      2. Type services.msc, and then click OK.
      3. Locate and select the service, "Smart Card Helper."
      4. Click Action, and then click Properties.
      5. Click Stop, if applicable.
      6. Change Startup Type to Manual.
      7. Click OK and close the Services window.
      8. Restart the computer.

      4. Scanning for and deleting the infected files
      1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
      2. Run a full system scan.
      3. If any files are detected as infected with W32.Femot.D.Worm, click Delete.
      4. Using Windows Explorer, look for the files, %Windir%\System32\Mofei.cfg and %s\ADMIN$\System32\MoFei.ver. Delete them if found.

      5. Deleting the values from the registry

      CAUTION : Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
      1. Click Start, and then click Run. (The Run dialog box appears.)
      2. Type regedit

        Then click OK. (The Registry Editor opens.)

      3. On Windows 95/98/ME, navigate to the key:


      4. In the right pane, delete the value:

        "NavAgent32"="%Windows%\System32\lasvr32.exe -v"

      5. On Windows NT/2000/XP, navigate to the key:


      6. In the right pane, set the value: ImagePath



      7. Exit the Registry Editor.

      Writeup By: Yana Liu