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Discovered: June 07, 2001
Updated: February 13, 2007 11:36:38 AM
Type: Virus

VBS.Lanus.gen is an encoded Visual Basic script (VBS) contained within a .htm or .html page. This script is viral, and when executed it infects .htm and .html files by appending itself to the end of the file. For the script to activate, you must have the Windows Scripting Host 5.1 or later installed and allow the ActiveX controls to run when the infected .htm or .html page is viewed.

Antivirus Protection Dates

  • Initial Rapid Release version June 07, 2001
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version June 07, 2001
  • Latest Daily Certified version August 09, 2016 revision 001

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

Writeup By: Brian Ewell

Discovered: June 07, 2001
Updated: February 13, 2007 11:36:38 AM
Type: Virus

An infected Web page contains the encoded Visual Basic script at the end of the file. If the page is viewed, it displays itself normally, and there is a random chance the viral script will execute. When it does, it first prompts you to allow its ActiveX controls to run. If you allow this, the script searches the drive and infects .htm and .html files found in the following locations:

  • The root folder of the drive
  • The \Windows\Help folder and its subfolders
  • The \Windows\System folder and its subfolders
  • The \Windows\Temp folder and its subfolders
  • The \Desktop folder and its subfolders
  • The \Desktop folder attributed to AllUsers and its subfolders

The script performs a check to verify whether it has already infected .htm and .html files. If it has already infected a file in a particular folder, it will not infect newer .htm or .html files present in that same folder. This holds true if the script is executed more than once.

The script requires that the Windows Scripting Host 5.1 or later be installed.


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.

Writeup By: Brian Ewell

Discovered: June 07, 2001
Updated: February 13, 2007 11:36:38 AM
Type: Virus

Run LiveUpdate to make sure that you have the most recent virus definitions.

  1. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
  2. Files detected as infected by VBS.Lanus.gen should be deleted and restored from backup if necessary.

Writeup By: Brian Ewell