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Discovered: December 29, 2001
Updated: February 13, 2007 11:58:39 AM
Also Known As: I-Worm.Maldal.d [KAV], I-Worm.Maldal.e [KAV], I-Worm.Maldal.f [KAV], W32/Maldal.d@MM [McAfee], W32/Maldal.e@MM [McAfee], W32/Maldal.f@MM [McAfee], W32/Maldal.g@MM [McAfee], WORM_MALDAL.D [Trend], WORM_MALDAL.E [Trend], WORM_MALDAL.F [Trend], WORM_MALDAL.G [Trend], W32/Maldal-D [Sophos], W32/Maldal-F [Sophos], W32/Maldal-G [Sophos], Win32.Maldal.D [CA], Win32.Maldal.E [CA], Win32.Maldal.F [CA], Win32.Maldal.G [CA]
Type: Worm
Systems Affected: Windows

W32.Maldal.D@mm is an extremely damaging worm. It was written and distributed on December 28, 2001. The virus code is in Visual Basic. It is about 27 KB in size and is packed using Aspack. The worm uses Microsoft Outlook to send itself to all contacts in your Microsoft Outlook address book.

Antivirus Protection Dates

  • Initial Rapid Release version December 29, 2001
  • Latest Rapid Release version January 19, 2018 revision 003
  • Initial Daily Certified version December 29, 2001
  • Latest Daily Certified version January 19, 2018 revision 007
  • Initial Weekly Certified release date December 29, 2001

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

Technical Description

When the worm is executed for the first time, it will installs itself as \Windows\System\Win.exe.

It then adds the value


to the registry key


so that the worm runs the next time that you start Windows. In most cases, however, because of the damage that is done by this worm, the computer will no longer load Windows.

Next, the worm obtains the computer name. This is done because the worm is programmed to send email messages with a subject line that includes the name of the computer. The attachment that is sent with the message is an .exe file. The name used for this attached file is composed of the computer name plus the .exe extension, for example, Johns PC.exe.

If the worm is executed a second time, the email message will have the subject "ZaCker" and an attachment named ZaCker.exe. This is because the worm renames the computer to "ZaCker."

The content of the mail will be any of the following (randomly chosen) lines:

Test this game
I wish u like it
I have got this file for you
Surprise !!!
download this game & have fun ;)
desktop maker ,you may need it ;)
have you ever got a gift !?
What women wants !
Don't waste any time ,Subscribe now
Make your pc funny !
new program from my fun groups
Map of the world
Create your Ecard
Send it to everybody you love
Its made by me ;)
Our symbol
If you have an elegant taste
Test your mind
1 + 1 = 3 !!!
Singer , searsh for any song and sing ;)
For everybody wants to marry a woman that he doesn't love !
nowadays , there is no womanhood !!  :P
Just Try to fix it
Keep these advertisements run and earn 0.25 $ per 10 minute ;)
See this file

W32.Maldal.D@mm is a retroworm (a worm virus that actively attacks antivirus programs in an effort to prevent detection). It deletes antivirus programs that it finds in the following folders:

  • Program Files\AntiViral Toolkit Pro
  • Program Files\Command Software\F-PROT95
  • eSafe\Protect
  • PC-Cillin 95
  • PC-Cillin 97
  • Program Files\Quick Heal
  • Program Files\FWIN32
  • Program Files\FindVirus
  • Toolkit\FindVirus
  • F-macro
  • Program Files\McAfeeVirusScan95
  • Program Files\Norton AntiVirus
  • TBAVW95
  • VS95
  • Rescue
  • Program Files\Zone Labs\

Finally, the worm deletes several files, including those with the file extensions .ini, .php, .exe, .com, .mpeg, .dat, .zip, .txt, .exe, .xls, .doc, and .jpg.


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.


NOTE: If the worm has already executed, it is likely that you will first have to reinstall the operating system and most (if not all) programs. In addition, most data files such as Microsoft Word documents, text files, and so on will have to be restored from a clean backup.

To remove the worm, delete all files that are detected as W32.Maldal.D@mm and remove the value that it added to the registry.

To remove the worm:

  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. If you cannot start Norton Antivirus, you may have to re-install it.
  3. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
  4. Run a full system scan.
  5. Delete all files that are detected as W32.Maldal.D@mm.

To edit the registry:

CAUTION : We strongly recommend that you back up the system registry before you make any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys that are specified. Please see the document How to back up the Windows registry before you proceed.
  1. Click Start, and click Run. The Run dialog box appears.
  2. Type regedit and then click OK. The Registry Editor opens.
  3. Navigate to the following key:

  4. In the right pane, delete the following value:

  5. Click Registry, and then click Exit.