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12 May 2001
13 February 2007
Also Known As:
VBS/Hard-A, VBS/Hard@mm

VBS.Hard.A@mm is a Visual Basic Script (VBS) worm that uses Microsoft Outlook Express. It arrives with an attachment named "" and a subject line of "FW: Symantec Anti-Virus Warning". This email was not distributed by Symantec. If you receive this email, delete it immediately.

There are some additional precautions that you can take to prevent this type of threat:
  • If you are using Norton AntiVirus 2001, a free program update that includes Script Blocking is available.Please run LiveUpdate to obtain this.
  • For other versions of Norton AntiVirus, SARC offers a tool to disable the Windows Scripting Host.

Antivirus Protection Dates

  • Initial Rapid Release version 12 May 2001
  • Latest Rapid Release version 08 August 2016 revision 023
  • Initial Daily Certified version 12 May 2001
  • Latest Daily Certified version 09 August 2016 revision 001
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

VBS.Hard.A@mm tries to disguises itself as a virus warning from Symantec. It arrives as:

Subject: FW: Symantec Anti-Virus Warning.



----- Original Message -----
From: <>
Subject: FW: Symantec Anti-Virus Warning


There is a new worm on the Net.
This worm is very fast-spreading and very dangerous!

Symantec has first noticed it on April 04, 2001.

The attached file is a description of the worm and how it replicates itself.

With regards,
F. Jones
Symantec senior developer

When is executed, VBS.Hard.A@mmworm does the following:

  1. It copies itself as the C:\ file.
  2. Then it tries to create a fake Symantec virus information page for a non-existent threat, VBS.AmericanHistoryX_II@mm. This fake web page is created as C:\ In creating this fake web page, it uses the helper files:
    • C:\Switch.bat
    • C:\{3050F4D8-98B5-11CF-BB82-00AA00BDCE0B}

      The latter will be created if the .hta file type is not registered as the hex-ID shown above. In this case, the worm runs the C:\Switch.bat to rename the second file to C:\
  3. Then, the worm creates the C:\www.symantec_send.vbs file, which contains the instruction to use Microsoft Outlook Express to send the file C:\ to everyone in your Microsoft Outlook Express address book. This script also creates a marking key in the Windows registry


    that is set to the value

  4. Next, VBS.Hard.A@mm creates the C:\Message.vbs file, which contains a message-displaying payload. The payload is triggered every November 24th. It displays the message:

  5. The worm then sets or creates several registry keys:
    • To the registry key


      it adds the following three values:
      • Outlook    C:\www.symantec_send.vbs

        This launches the VBS file that sends out the email message.
      • Symantec   C:\infected with Virus.vbs

        Since there is no such file being dropped, this registry key modification does not affect the system.
      • Message   C:\message.vbs

        This launches the message-displaying script, which will only display the message on November 24th.
    • In the registry key

      HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main

      it changes the value data of

      Start Page



      This sets the start page of Internet Explorer to the fake virus information web page.


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.

To remove this worm, delete files detected as VBS.Hard.A@mm, undo the changes that it made to the registry, and reset the Internet Explorer Start Page

To remove the worm files:
  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
  3. Delete any files detected as VBS.Hard.A@mm

To edit the registry:

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

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

  5. Click Registry, and then click Exit.

NOTE: It is not necessary to remove the marking key that was added by the worm.

To reset the Start Page:
  1. Start Microsoft Internet Explorer.
  2. Connect to the Internet and go to the page that you want to set as your start page.
  3. Click Tools and then click Internet Options.
  4. On the General tab, click Use Current, and then click OK.

Writeup By: Raul Elnitiarta