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Discovered: August 29, 2003
Updated: February 13, 2007 12:06:29 PM
Type: Worm
Systems Affected: Windows

W32.HLLW.Lacon@mm is mass-mailing worm that attempts to spread itself through email, mIRC, and file-sharing networks.

The email has the following characteristics:

Subject : National No Call Registry Info
Attachment : No Call List.exe
Message : (One of the following)

  • You've probably heard about the National No Call Registry to stop telemarketers. Well I tried it just yesterday and so many people are using it I couldn't get through. But good news, they just issued this program to automate everything, check the attachment!

    Love ya!
  • Finally they created a program to stop those annoying telemarketers, it adds you to the National No Call Registry automatically. Check the attachment!

    Keep in touch!
  • Get added to the National No Call List to make it illegal for telemarketers to call you, just click the attachment to add yourself.

    Talk to you later!
  • I just saw this on the local news. You can add yourself to this National No Call List so telemarketers stop calling. I just did it, its real easy. Just click the attachment to add yourself!

    See you soon!
This threat is written in the Microsoft Visual Basic (VB) programming language, and the VB run-time libraries must be installed for W32.HLLW.Lacon@mm to run.

Antivirus Protection Dates

  • Initial Rapid Release version August 29, 2003
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version August 29, 2003
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date September 03, 2003

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

Technical Description

When W32.HLLW.Lacon@mm is executed, it performs the following actions:

  1. Copies itself as:
    • %System%\Bndt32.exe
    • %System%\No Call List.exe
    • %Startup%\Configuration Utility.exe

      • %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
      • %Startup% is a variable. The worm locates the Startup folder and copies itself to that location.

  2. Adds the value:


    to the registry key:


  3. If the day of the month is 10, the worm does the following:
    1. Sets the Internet Explorer home page to:

      http:/ /homestarrunner.com/systemisdown.html

    2. Displays the following message:

    3. Shuts down all the processes and logs off the user.

  4. Emails itself to all the contacts in the Windows Address Book.

  5. Creates the plain text file, %System%\Bndt32.txt, in the folder with the following content:

    The deed has been done. W32.HLLW.NoCall by DimenZion

  6. If the worm finds mIRC, it attempts to overwrite the Script.ini file and copy itself to the mIRC folder as Do Not Call Registry.ex_

  7. Searchs for the following folders:
    • %ProgramFiles%\kazaa lite\my shared folder
    • %ProgramFiles%\kazaa\my shared folder
    • %ProgramFiles%\kmd\my shared folder
    • %ProgramFiles%\grokster\my grokster
    • %ProgramFiles%\bearshare\shared
    • %ProgramFiles%\edonkey2000\incoming
    • %ProgramFiles%\morpheus\my shared folder
    • %ProgramFiles%\limewire\shared
    • %ProgramFiles%\winmx\shared
    • %ProgramFiles%\ICQ\Shared Files
    • %ProgramFiles%\Gnucleus\downloads
    • c:\My shared folder\

      NOTE: %ProgramFiles% is a variable that refers to the path to the program files folder. By default, this is C:\Program Files.

  8. If the worm finds any of the above folders, it will copy itself to that folder as:
    • Microsoft Office XP Keygen [FairLight].exe
    • DeskTop Stripper - HOT!.exe
    • AIM Password Hack.exe
    • XP Professional Crack [FairLight].exe
    • Ad-aware 6.0 Serial.exe
    • 1,000 Porn Site Passwords.exe
    • Adobe Photoshop 8.x Crack.exe
    • Battlefield 1942 - Secret Weapons of World War II Serial [FairLight].exe
    • Battlefield 1942 - The Road to Rome Crack.exe
    • Civilization III - Conquest Crack [FairLight].exe
    • Command & Conquer Generals Crack [FairLight].exe
    • Conflict - Desert Storm II - Back to Baghdad Serial.exe
    • And1 Complete Mixtapes.exe
    • Counter-Strike - Condition Zero No-CD [FairLight].exe
    • Delta Force - Black Hawk Down +13 Trainer.exe
    • EverQuest 2 +18 Trainer.exe
    • FIFA Soccer 2004 Crack [FairLight].exe
    • FlashFXP 1.4 Serial.exe
    • Battlefield 1942 +12 Trainer.exe
    • Grand Theft Auto - Vice City Crack [FairLight].exe
    • Grand Theft Auto - Vice City All Missions Trainer.exe
    • X-Box Halo - PC Emulator.exe
    • KaZaA Speedup 3.03 Crack.exe
    • KaZaA Lite K++ Edition 2.1.1.exe
    • mIRC 6.03 Install.exe
    • Lords of EverQuest Crack [FairLight].exe
    • Macromedia Flash MX 6.x Serial [GimpsRus].exe
    • Madden NFL 2004 Crack [FairLight].exe
    • Medal of Honor - Allied Assault Breakthrough Crack [FairLight].exe
    • Midtown Madness 3 FULL.exe
    • Nero Burning ROM 6.x Crack [FairLight].exe
    • Neverwinter Nights - Shadows of Undrentide Serial.exe
    • NHL 2003 Crack [FairLight].exe
    • Paint Shop Pro 9.x Serial.exe
    • Return to Castle Wolfenstein Enemy Territory Crack [FairLight].exe
    • SimCity 4 Rush Hour Crack [FairLight].exe
    • Star Wars Jedi Knight - Jedi Academy Crack.exe
    • Warcraft III - The Frozen Throne Crack [FairLight].exe
    • WinAce 2.x Serial.exe
    • WindowBlinds 4.0 Keygen.exe
    • WinRAR 3.12 Crack [FairLight].exe
    • WinZip 9 Crack [FairLight].exe
    • Roxio Easy CD Creator 5 Platinum Crack [FairLight].exe
    • ZoneAlarm 3.7.143 Keygen.exe
    • NewDawn DivX Player 6.7 Full + Serials.exe
    • NewDawn DVD Ripper Pro 9.0 + serial.exe
    • Norton Antivirus 2003 Professional Crack [FairLight].exe
    • Cable and DSL Modem Speed Accelerator Pro.exe
    • Pop-up Blocker Pro 8.4 Full Version.exe
    • Hotmail Hack [Pr0gz].exe
    • Win every bid on e-bay.txt.exe
    • Diablo 2 All Weapons Trainer [Gl0ry].exe
    • Kaspersky - The REAL AntiVirus.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. Reverse the changes that the worm made to the registry and restart the computer.
  4. Run a full system scan and delete all the files detected as W32.HLLW.Lacon@mm. Manually delete the file, %System%\Bndt32.txt.
  5. Reset the Internet Explorer home page.
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. Reversing the changes that the worm made to 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. Navigate to the key:


  4. In the right pane, delete the value:


  5. Exit the Registry Editor.
  6. 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.HLLW.Lacon@mm, click Delete.
  4. Using Windows Explorer, delete the file, %System%\Bndt32.txt.

5. Resetting the Internet Explorer home page
  1. Start Microsoft Internet Explorer.
  2. Connect to the Internet and go to the page that you want to set as your home page.
  3. Click Tools, and then click Internet Options.
  4. In the Home page section of the General tab, click Use Current, and then click OK.

Writeup By: Robert X Wang