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Discovered: June 29, 2004
Updated: February 13, 2007 12:24:39 PM
Also Known As: VBS.Entice [Kaspersky], WORM_YESENIA.A [Trend Micro]
Type: Worm
Systems Affected: Windows

W32.Ainesey.A@mm is a mass-mailing worm that sends a copy of itself to all the email addresses gathered from the computer and infects Microsoft® Office® files.

The subject, body, and attachment name in the email vary.

Antivirus Protection Dates

  • Initial Rapid Release version June 30, 2004
  • Latest Rapid Release version February 19, 2013 revision 016
  • Initial Daily Certified version June 30, 2004
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date June 30, 2004

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

Technical Description

When W32.Ainesey.A@mm is executed, it performs the following actions:

  1. Creates a copy of itself as %Windir%\Msiexec32.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 that location.

  2. Creates and runs the file named %Windir%\Winexec.exe.vbs.
    This file is detected as W32.Ainesey.A@mm!vbs.

  3. Adds the values:


    to the following registry key:


  4. Searches local hard drives and network drives for files with the following extensions and overwrites those files:
    • .vbs
    • .vbe
    • .js
    • .jse
    • .css
    • .wsh
    • .sct
    • .hta
    • .mp3
    • .wma

      The worm appends a .vbs extension to .js, .jse, .css, .wsh, .sct, .hta, .mp3, and .wma files.

  5. Adds the values:


    to the following registry keys:
    • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\10.0\Word\Security
    • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\9.0\Word\Security
    • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\10.0\Excel\Security
    • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\9.0\Excel\Security
    • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\10.0\PowerPoint\Security
    • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\9.0\PowerPoint\Security

      which decreases security settings in Microsoft Word, Excel, and PowerPoint.

  6. Runs a Word macro virus if Microsoft Word is open.
    This virus is detected as W97M.Melissa.Variant; it does the following.
    1. The macro is set to execute whenever the infected document is opened.
    2. When executed, it adds the values:


      to the following registry keys:
      • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\10.0\Word\Security
      • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\9.0\Word\Security

    3. It then changes the following settings:
      • Disables the Macro command on the Tools menu
      • Disables the Security option on the Macro menu
      • Disables virus protection in Microsoft Word
      • Prevents prompting when saving changes to the Normal.dot template
      • Prevents prompting when converting files being opened

    4. If there is no file called Msiexec32.exe in the Microsoft Word installation folder, then the worm drops the W32.Ainesey.A executable file into that folder and executes it.
    5. The virus inserts itself into any open documents with the module name Focg.
    6. If the Normal.dot template does not contain a module called Focg, the virus inserts itself into the template, using that module name.
      The viral macro in Normal.dot executes when the document closes, instead of when it opens.
    7. The macro then saves the infected document.

  7. If Microsoft PowerPoint is open, a PowerPoint macro virus is launched
    This macro virus is detected as O97M.Ainesey.C
    1. When executed, it drops the following files, executes them, and then deletes them.
      • %temp%\1.reg
      • %temp%\2.reg

        These files add the values:


        to the registry keys:
      • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\10.0\PowerPoint\Security
      • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\9.0\PowerPoint\Security
    2. If the file named %Windir%\Msiexec32.exe doesn't already exist, it creates and executes the file.
      This file is the W32.Ainesey.A@mm executable.
    3. It then enumerates through the open PowerPoint presentations and deletes the content of any VBA module that is not called Yesenia.
    4. It then copies itself into every open PowerPoint presentation with the module name Yesenia
    5. It enumerates through every shape in every open presentation.
      If the shape does not have an action for the ppMouseOver event (which is triggered whenever the mouse pointer is on the shape), then it attempts to set the action to execute the Yesenia module.
      This attempt fails due to a program bug.

  8. If Microsoft Excel is open, an Excel macro virus is launched.
    This macro virus is detected as O97M.Ainesey.C.
    1. The virus first creates the following files:
      • %temp%\1.reg
      • %temp%\2.reg

    2. It then executes the two files dropped, which sets the following registry entries, in order to lower the security settings of Microsoft Excel 9.0 and 10.0:
      • HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Excel\Security\Level=1
      • HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Excel\Security\DontTrustInstalledFiles=0
      • HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Excel\Security\AccessVBOM=1
      • HKEY_CURRENT_USER\Software\Microsoft\Office\9.0\Excel\Security\Level=1
      • HKEY_CURRENT_USER\Software\Microsoft\Office\9.0\Excel\Security\DontTrustInstalledFiles=0

    3. After executing the following files, it deletes them:
      • %temp%\1.reg
      • %temp\2.reg

    4. If %Windir%\Msiexec32.exe doesn't exist, that file is created and executed.
      This file is the W32.Ainesey.A@mm executable.
    5. It then searches all open Microsoft Excel workbooks and infects all worksheets.
    6. It searches for a file named Personal.xls in the Excel startup folder, creating it if it does not already exist.
      The virus then infects Personal.xls, which causes the virus will be loaded each time a Microsoft Excel workbook is opened.

  9. Finally, it emails copies of itself to the email addresses gathered from the system.

    The email has the following characteristics:

    Subject: (One of the following)
    • Improve your site
    • Quiz
    • All Under 15
    • Sexy game
    • Shield PAK Installation
    • Secure Communications Inc.
    • Cracks
    • Sex Farm
    • Adult contents
    • Under 18 Teens Nudes
    • Quieres mejorar tu pagina
    • My Rom List
    • IE Plug-in
    • NS Plug-in
    • Honey ;)
    • Damn crack...
    • Disk tool
    • freeIRC beta mail list
    • Necesitas seriales
    • cool mail
    • why
    • Crack para windows XP
    • benchmark

      Body: (One of the following)
    • Hi!
    • Your page is nice.
    • Test this js scripts and tell me what do you think.
    • Hello,
    • Take a look to this little app!
    • Las fotos que siempre as sonado
    • Take a look at this new archiver! 30 trial version.
    • Do you feel secure? Run this small program to see if your communications are safe.
    • Ask if you want something ;)
    • Sex Farm! Take a look at this little demo for free.  Adult content!!!
    • Prueba este programa y luego me cuentas
    • Nota: Version de Evaluacion por 30 dias
    • How goes fine here. There is the little app i told you.
    • I love you
    • Thanks you for the information.
    • There is my list...
    • There is the plug-in for IE... ;) send me comments.
    • There is the plug-in for NS... ;) send me comments.
    • Hi honey!
    • to leave mail list...
    • I'm trying to make run this shit but... please test it if ya can.
    • try this. 30 trial version.
    • See you!
    • Cool pics you send me!!! try this little game... rulez!
    • Last Beta 0.6.
    • Reply with subject
    • un-subscribe
    • Este programa solucionara tus problemas
    • I'm testing my new cool mail client... rockz! and is smallllll ;)
    • What can i do? please reply as soon as posible.
    • Pruebalo es una maravilla
    • this makes you feel better, there's a benchmark.

      Attachment: (One of the following)
    • Setup.exe
    • Teenies.exe
    • SCommSetup.exe
    • clist.exe
    • sfarm.exe
    • Under18.exe
    • instalar.exe
    • myList.exe
    • ie-pin.exe
    • ns-pin.exe
    • crack.exe
    • drDisk.exe
    • powerDick.exe
    • setupb.exe
    • Serial.exe
    • smail.exe
    • doc.exe
    • winXPcrak.exe
    • bdbench.exe


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.


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.
    Delete all the files detected as W32.Ainesey.A@mm.
    Repair all the files detected as O97M.Ainesey.C or W97M.Melissa.Variant.
  4. Restore the values that were modified in the registry.
  5. Restore the Microsoft Office settings

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 have finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the previously mentioned 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 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. 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.Ainesey.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. If any files are detected as infected with O97M.Ainesey.C or W97M.Melissa.Variant, click Repair.

4. To restore the values that were modified in the registry

WARNING: 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 the following:


  3. Click OK.
    The Registry Editor opens.

  4. In the Registry Editor, navigate to the key:


  5. In the right pane, delete the values:


  6. Restore the original values of the settings:


    in the registry keys:


  7. Exit the Registry Editor.

5. To restore Microsoft Office settings

a. Refer to the Microsoft Office documentation for details on how to restore the following settings:
    • The Macro command on the Tools menu
    • The Security command on the Macro menu
    • Virus protection and macro security settings in Microsoft Word
    • Prompting when saving changes to the Normal.dot template
    • Prompting when converting files that are being opened

Writeup By: Jeong Mun