Discovered: December 15, 2006
Updated: February 13, 2007 1:02:53 PM
Systems Affected: Windows

W32.Memesa is a worm that attempt to email itself out as an attachment, change the desktop background, and open local pages in Internet Explorer.

Antivirus Protection Dates

  • Initial Rapid Release version December 15, 2006
  • Latest Rapid Release version December 15, 2006
  • Initial Daily Certified version December 15, 2006
  • Latest Daily Certified version December 15, 2006
  • Initial Weekly Certified release date December 20, 2006

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

Writeup By: Hiroshi Shinotsuka

Discovered: December 15, 2006
Updated: February 13, 2007 1:02:53 PM
Systems Affected: Windows

When W32.Memesa is executed, it performs the following actions:

  1. Creates the following files:

    • %Windir%\svchost.exe
    • %Windir%\dllhost.exe
    • %Windir%\windos.exe
    • [DRIVE LETTER]\agnes vs f4.exe
    • [DRIVE LETTER]\foto panas agnes.exe
    • [DRIVE LETTER]\foto mesra f4 vs agnes monica.exe
    • %Windir%\meme.bmp
    • %Windir%\memesayang.htm
    • %Windir%\happyday.htm
    • %Windir%\putuscinta.htm

      Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.

  2. Adds the values:

    "sysshell" = "%Windir%\svchost.exe"
    "dllhost" = "%Windir%\dllhost.exe"

    to the registry subkey:


    so that it starts when Windows starts.

  3. Modifies the values:

    "DisableRegistryTools" = "1"
    "DisableTaskMgr" = "1"

    in the registry subkey:


    which disable access to the Registry Editor and the Task Manager.

  4. Modifies the values:

    "CheckedValue" = "1"
    "DefaultValue" = "1"

    in the registry subkey:


  5. Modifies the values:

    "CheckedValue" = "2"
    "DefaultValueSUCCESS" = "2"

    in the registry subkey:


  6. Modifies the values:

    "Hidden" = "1"
    "HideFileExt" = "1"

    in the registry subkey:


  7. Modifies the value:

    "NoFolderOptions" = "1"

    in the registry subkey:


  8. Searches disk drives for files with the following extention:

    • .xls
    • .pdf
    • .doc
    • .jpg

  9. Copies itself as an executable using the file's name for all files found. For example, if there is a C:\aaa\test.jpg, it copies itself as C:\aaa\test.exe.

  10. Sets desktop background to the following picture:

  11. May send ICMP Echo Requests to the following URL:


  12. Attempts to email itself as an attachment to an email with the following characteristics:

    One of the following:
    • Sstt..! foto2 panas agnes dengan f4!
    • FWD: foto mesra agnes vs f4!

      One of the following:
    • Apakah Anda sedang jatuh cinta? Apakah cinta Anda cinta sejati? Check this out!
    • Ssstt, kumpulan foto mesra f4 dengan agnes monica!

      One of the following:
    • foto mesra f4 vs agnes
    • agnes vs
    • foto panas

      Note: The mass-mailing routine may fail. In some cases, the worm opens an email window, sets the email subject and body, and sometimes attaches itself. However, it does not appear to be able to send the message.

  13. May display a locally generated Web page in Internet Explorer. The page contains the following text:


Writeup By: Hiroshi Shinotsuka

Discovered: December 15, 2006
Updated: February 13, 2007 1:02:53 PM
Systems Affected: Windows

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. Run a full system scan.
  4. Delete any values 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:
When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable 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:
    • If you use Norton AntiVirus 2006, Symantec AntiVirus Corporate Edition 10.0, or newer products, LiveUpdate definitions are updated daily. These products include newer technology.
    • If you use Norton AntiVirus 2005, Symantec AntiVirus Corporate Edition 9.0, or earlier products, LiveUpdate definitions are updated weekly. The exception is major outbreaks, when definitions are updated more often.
  • 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 Virus Definitions (Intelligent Updater).

    The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions. For detailed instructions read the document: How to update virus definition files using the Intelligent Updater.

3. To run a full system scan
  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, follow the instructions displayed by your antivirus program.

Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do 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, restart the computer in Normal mode and proceed with the next section.

Warning messages may be displayed when the computer is restarted, since the threat may not be fully removed at this point. You can ignore these messages and click OK. These messages will not appear when the computer is restarted after the removal instructions have been fully completed. The messages displayed may be similar to the following:

Title: [FILE PATH]
Message body: Windows cannot find [FILE NAME]. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.

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 subkeys only. For instructions refer to the document: How to make a backup of the Windows registry.
  1. Click Start > Run.
  2. Type regedit
  3. Click OK.

    Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.

  4. Navigate to the subkey:


  5. In the right pane, delete the value:

    "sysshell" = "%Windir%\svchost.exe"
    "dllhost" = "%Windir%\dllhost.exe"

  6. Restore the vaules for the following registry entries to their previous settings:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\"DisableRegistryTools" = "1"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\"DisableTaskMgr" = "1"
    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL\"CheckedValue" = "1"
    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL\"DefaultValue" = "1"
    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\NOHIDDEN\"CheckedValue" = "2"
    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\NOHIDDEN\"DefaultValueSUCCESS" = "2"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\"Hidden" = "1"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\"HideFileExt" = "1"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\"NoFolderOptions" = "1"

  7. Exit the Registry Editor.

Writeup By: Hiroshi Shinotsuka