Threat Explorer

The Threat Explorer is a comprehensive resource consumers can turn to for daily, accurate, up-to-date information on the latest threats, risks and vulnerabilities.

VBS.Elva.Worm

VBS.Elva.Worm

Discovered:
27 September 2000
Updated:
13 February 2007

This worm uses Microsoft Outlook to spread. Using MAPI, it sends itself to all email addresses in your Microsoft Outlook address book.

Antivirus Protection Dates

  • Initial Rapid Release version 27 March 2001
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 27 March 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.

For VBS.Elva.Worm to execute, the Windows Scripting Host must be installed, and the Windows file, Mshta.exe, must exist. This worm is written in VBScript, which can only execute in Microsoft Internet Explorer or in Internet Explorer-compatible Web browsers.

This worm arrives as:

Subject: BIRTHDAY CARD !!!

Message:
Hello Jo,
Happy birthday ELVA forever.T
This I made birthday card for you.
Please open it and I hope you like.

Attachment: Card.hta

When executed, VBS.Elva.Worm does the following:
  1. It uses MAPI to send itself to all email address in your Microsoft Outlook address book.
  2. It creates the \Windows\Elva's Page.url file. This URL file points to the Web site http: //www.jasonnet.cc/elva.
  3. It creates Fs.com and Fs.vbe in the \Windows folder.
  4. It creates Fs.vbs in the \Windows\System folder.
  5. On August 24 it displays the message

    -=Happy birthday=- I love ELVA 4 ever
  6. It adds the value

    FS   WINDOWS\SYSTEM\FS.VBS

    to the registry key

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices

    This causes the worm to run when Windows starts.
  7. VBS.Elva.Worm then attempts to infect the Microsoft Word Normal.dot template. However, due to errors in the virus code, the infection does not occur.


Recommendations

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.Elva.Worm, deleted the files dropped by the worm, 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. 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.Elva.Worm.
  4. Using Windows Explorer, locate the following files, and if they exist, delete them:
    • \Windows\Elva's Page.url
    • \Windows\Fs.com
    • \Windows\Fs.vbe
    • \Windows\System\Fs.vbs

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. Navigate to the following key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices
  4. In the right pane, delete the following value:

    FS   WINDOWS\SYSTEM\FS.VBS
  5. Click Registry, and click Exit to save the changes and exit Registry Editor.


Writeup By: Gor Nazaryan