Threat Explorer

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VBS.San.B@m

VBS.San.B@m

Discovered:
16 March 2001
Updated:
13 February 2007

VBS.San.B@m is a script worm which spreads through email. The worm utilizes a known Microsoft Outlook Express security hole (Scriptlet.TypeLib) so that a viral file is created on the system without having to run any attachment. Simply reading the received email message causes the virus to be placed on the system. Microsoft has patched this security hole. The patch is available at:

http://www.microsoft.com/technet/ie/tools/scrpteye.asp

If you have a patched version of Outlook Express, this worm will not work automatically.

The worm copies itself into the StartUp folder and sets itself as the default signature for Microsoft Outlook Express. It also modifies the default start page for Internet Explorer to connect to a Web site that contains another worm, VBS.Valentin@mm.

Antivirus Protection Dates

  • Initial Rapid Release version 16 March 2001
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 16 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.

Once the worm has infected a system, it copies itself to the StartUp folder as the Loveday14-c.hta file. This folder is hardcoded in the worm as C:\Windows\Start Menu\Programs\StartUp. If the computer is running the Spanish version of Windows, it copies it to the C:\Windows\Menú Inicio\Programas\Inicio folder. This allows the worm to execute every time that the computer is started.

The worm creates the Index.html file in the \Windows\System folder. This file becomes the default signature for Outlook Express. This allows the worm to spread to other users when you send email. This is the same method by which WScript.KakWorm distributes itself.

If the payload is triggered, the worm deletes files contained within subfolders on drive C. This means that C:\Windows will not be deleted, but the contents of C:\Windows\System will be. It also renames subfolders by appending "happysanvalentin" to them. C:\Windows\System thus becomes C:\Windows\Systemhappysanvalentin.

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 recover from this infection:

NOTE: If the payload has triggered on your system, you may have to reinstall Windows before you can perform any of the following steps.
  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 that are detected as infected by VBS.San.B@m.
  4. Click Start, point to Find, and then click Files or Folders.
  5. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
  6. In the Named box, type (or copy and paste) the following file name:

    loveday14-c.hta
  7. Click Find Now. When found, delete the Loveday14-c.hta file.
  8. Within Microsoft Outlook Express, restore your default signature.
  9. Restore any deleted files from backup or reinstall the software. If necessary, rename any subfolders that were changed by the worm back to their original names.



Writeup By: Brian Ewell