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security response

W32.Fili.A@mm

Category 2
Discovered on: October 05, 2004
Last Updated on: October 12, 2004 09:15:30 AM

W32.Fili.A@mm is a generic Visual Basic worm that propagates via Microsoft Outlook and through peer-to-peer file-sharing networks. It can also spread via mIRC.

The email has a variable subject and attachment name. The attachment will have a .scr, .pif, .bat, .com, .cmd, or .exe file extension.

Notes:

  • Virus definitions released prior to October 6, 2004 will detect this threat as Bloodhound.Packed or Bloodhound.W32.5.
  • Virus definitions released prior to October 11, 2004 will detect this threat as W32.Fili@mm.

Also Known As: Bloodhound.Packed, Bloodhound.W32.5, I-Worm.VB.q [Kaspersky], WORM_FILI.A [Trend Micro]
Type: Worm
Infection Length: 20,480 bytes
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP
Systems Not Affected: DOS, Linux, Macintosh, Novell Netware, OS/2, UNIX, Windows 3.x

protection
  • Virus Definitions (Intelligent Updater) *
  • October 06, 2004

  • Virus Definitions (LiveUpdate™) **
  • October 06, 2004

    *

    Intelligent Updater definitions are released daily, but require manual download and installation.
    Click here to download manually.

    **

    LiveUpdate virus definitions are usually released every Wednesday.
    Click here for instructions on using LiveUpdate.

    threat assessment

    Wild

    Threat Metrics

    Low Medium High

    Wild:
    Low

    Damage:
    Medium

    Distribution:
    High

    Damage

    Distribution

    technical details

    When W32.Fili.A@mm runs, it performs the following actions:

    1. Copies itself to %System%\pilif.exe.

      Note: %System% is a variable that refers to the System folder. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

    2. Adds the value:

      "Pilif" = "%System%\pilif.exe"

      to the registry key:

      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\

      so that the worm runs when Windows starts.

    3. Creates the following files:
    4. Searches for KaZaA, Morpheus, eDonkey, Grokster, limewire, ICQ, and WinMX-shared directories and copies itself as:
    5. Adds the value:

      "DisableTaskMgr" = "00000001"

      to the registry key:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
      Policies\System

      to disable the task manager.

    6. Sends itself as an email attachment to all the email addresses in the Microsoft Outlook address book. The email has the following characteristics:

      Subject: (one of the following)
    7. Searches the system for mirc or mirc32 and adds text to the file script.ini in order to send itself via IRC.

    8. Attempts to disable the following antivirus and security-related processes, if they are running:
    9. Runs a process with the same name as the copy of the worm, for example: pilif.exe

    10. Attempts to shut down and restart the infected computer by presenting the user with the shutdown menu.

    recommendations

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

    removal instructions

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

    Important: On computers running Norton AntiVirus 2005 or later, the QuickScan tool will automatically search for and remove malicious threats when new virus definitions are downloaded. While every effort has been made to ensure that the QuickScan tool removes all the traces of a malicious threat from an infected computer, we advise that you confirm that all the files and registry entries have been removed. We recommend following the manual removal steps and deleting any threat-related files or registry entries remaining on the computer.

    1. Disable System Restore (Windows Me/XP).
    2. Update the virus definitions.
    3. Run a full system scan and delete all the files detected as W32.Fili.A@mm.
    4. Delete the value that was added to the registry.
    For specific details on each of these steps, read the following instructions.

    1. To disable 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:


    Note:
    When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.


    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. To update 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 daily. 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. To scan for and delete 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.Fili.A@mm, click Delete.


      Note:
      If your Symantec antivirus product reports that it cannot delete an infected file, Windows may be using the file. To fix this, run the scan in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode." Once you have restarted in Safe mode, run the scan again.

      (After the files are deleted, you can leave the computer in Safe mode and proceed with section 4. When that is done, restart the computer in Normal mode.)

    4. To delete the value from the registry


    Important:
    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 > Run.
    2. Type regedit

      Then click OK.

    3. Navigate to the key:

      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    4. In the right pane, delete the value:

      "Pilif" = "%sysdir%\pilif.exe"

    5. Navigate to and reset the following registry key:

      HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
      Policies\System


    6. Exit the Registry Editor.

    Revision History:

    October 12, 2004: Renamed from W32.Fili@mm to W32.Fili.A@mm.


    Write-up by: Maryl Magee