Threat Explorer

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21 September 2001
13 February 2007
Also Known As:

VBS.Erul.A@mm is a simple Visual Basic Script (VBS) worm that sends email to all contacts that are in the Microsoft Outlook address book. It searches for all files that have the extension .vbs and overwrites them with itself. It also creates a copy of itself in the C:\Windows folder as Failure.dll.vbs.

Antivirus Protection Dates

  • Initial Rapid Release version 21 September 2001
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 21 September 2001
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When executed, this worm copies itself as C:\Windows\Failure.dll.vbs.

Next, it creates the value

Failure.dll   wscript.exe c:\windows\Failure.dll.vbs %
in the registry key


which causes the worm to run when you start Windows.

If it has not already mailed itself, it has a 50-percent chance of displaying a message with the title "VBS.Failure.A" and the text


It then mails itself to all contacts that are in the Microsoft Outlook address book. This worm adds itself as an attachment to every email message that it mails out.
The message has the following characteristics:

Subject: Alarm!! Virus Alert
Message:   Virus Alert!!
Attachment: Failure.dll.vbs.

Next, the worm attempts to overwrite all .vbs files on all mapped and local drives with itself.

Finally, after the email routine is finished, the worm creates the registry key


with the value 1.


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.Erul.A@mm and remove the value that the worm added to the registry /Run key.

To delete VBS.Erul.A@mm:
  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. 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.
  3. Run a full system scan.
  4. Delete all files that are detected as VBS.Erul.A@mm. Deleted files will have to be replaced from a clean backup.

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:

    Failure.dll  wscript.exe c:\windows\Failure.dll.vbs %
  5. Click Registry, and then click Exit.

NOTE: It is not necessary to remove the key HKEY_CURRENT_USER\Software\Failure\mailed because it is harmless and will prevent future mailings if the computer were to be reinfected by this worm.

Writeup By: Dave Adamczyk