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Discovered: August 12, 2003
Updated: February 13, 2007 12:05:53 PM
Systems Affected: Windows

W32.HLLW.Habrack is a worm that attempts to spread through file-sharing networks. The worm also has backdoor functionalities that allow its creator to control a compromised system.

When W32.HLLW.Habrack is executed, it displays fake messages. Refer to the "Technical Details" section for illustrated examples.

This threat is written in the Microsoft Visual Basic programming language.

Antivirus Protection Dates

  • Initial Rapid Release version August 13, 2003
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version August 13, 2003
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date August 13, 2003

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

Technical Description

When W32.HLLW.Habrack is executed, it does the following:

  1. Displays the following fake messages:

  2. After you input your name and password, the worm creates a file, C:\Password.Txt, and saves the name and password in this file.

  3. Copies itself as the following:
    • C:\Windows\WinSys.Dll
    • C:\Windows\Rundlls.exe
    • C:\Windows\Wscript.exe
    • C:\My Shared Folder\Linux Mandrake.Zip
    • C:\My Shared Folder\Microsoft® Visual Basic 7.exe
    • C:\My Shared Folder\Microsoft ® Windows Xp + Gen.exe
    • C:\My Shared Folder\Norton AntiVirus 2003 + Crack.exe
    • C:\My Shared Folder\Norton Ghost KeyGen.exe
    • C:\My Shared Folder\Msn 8 Cracked.exe
    • C:\My Shared Folder\Msn6Plus.exe
    • C:\Program Files\Panda AntiVirus Trial\Core files\Panda.exe

  4. Creates a folder, C:\Windows\System32\Norton\Defenitions\File\Break, and copies itself as the following:
    • WinSys.Dll
    • WinSys.exe

  5. Creates the following files:
    • C:\Home.Vbs (142 bytes)
    • C:\Me.Html (52 bytes)
    • C:\hello.bat (51 bytes)
    • C:\Windows\Wscript.bat (80 bytes)

      NOTE: These text files and are not viral by themselves. Therefore, Symantec antivirus products do not detect them. Manually delete them if this worm has infected your system.

  6. Appends 8,640 bytes to the end of the file, C:\Program Files\Norton AntiVirus\Ccimscan.exe, each time the worm runs.

  7. Appends 4,320 bytes to the end of the file, C:\Program Files\Norton AntiVirus\Qconsole.exe, each time the worm runs.

  8. Deletes the following files:
    • C:\Program Files\Yahoo!\Messenger\res_msgr.dll
    • C:\Program Files\MSN Messenger\msgslang.dll

  9. Attempts to open a browser window and connect to Windows Update.

  10. If the current system date is October 7, 2003, the worm may display a message, "Happy Birthday ...:::Hackers:::... "

  11. Attempts to delete the following:
    • C:\Windows\*.dll
    • C:\Winnt\*.dll
    • C:\Windows\Desktop\*.ink

  12. Opens a randomly chosen TCP port to connect to its creator.


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 and delete all the files detected as W32.HLLW.Habrack.
  4. Restore the system files that the worm deleted.

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. 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.Habrack, click Delete.

4. Restoring the system files that the worm deleted
The following documents provide general instructions extracting files. This information is provided for your convenience. The exact steps may vary slightly depending on the configuration of your operation system, the location of the files, and so on. For additional information, read the Help files, contact Microsoft, or refer to the following Windows documentation:

Writeup By: Yana Liu