Threat Explorer

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29 April 2003
13 February 2007
Also Known As:
VBS/Terrosist.ow [McAfee]
Systems Affected:

VBS.Terrosist is a Visual Basic (VB) Script virus that infects HTML files. It targets files that have the extensions .htt, .htm, .html, .asp, .php, or .jspin.

Antivirus Protection Dates

  • Initial Rapid Release version 30 April 2003
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 30 April 2003
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date 30 April 2003
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When VBS.Terrosist is executed, it does the following:
  1. Copies itself as:
    • %WinDir%\System\Blank.htm
    • %WinDir%\Web\Folder.htt
    • %WinDir%\System32\Folder.htt
    • %WinDir%\Folder.htt

      NOTE: If any files with these names already exist, VBS.Terrosist will infect the existing file or files.

  2. Modifies the files:
    • %WinDir%\Web\Webview.css
    • %WinDir%\Web\Desktop.ini
    • %WinDir%\System32\Desktop.ini
    • %WinDir%\Desktop.ini

      so that the file, Folder.htt, which is a copy of the virus, is executed when that particular folder is viewed in Explorer.

  3. Searches for and infects the files that are in the local directory and have the extensions .htt, .htm, .html, .asp, .php, or .jspin.

  4. On the 30th of April, June, August, October, and December of every year, VBS.Terrosist will rename the Win.ini and System.ini files to Won.chk and System.chk, respectively.

Additional actions
If the registered owner of the system is "Indonesian Today," then VBS.Terrosist does the following:
  1. Overwrites or creates the following keys and values:

    HKEY_CURRENT_USER\Control Panel\International
    "s1159"="Anti AS"
    "s2359"="Anti Shit"
    "sTimeFormat"="HH:mm:ss tt"

    "<default>"="My Komputer"



    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    "Local Page"="%windows%\system\blank.htm"
    "Start Page"="%windows%\system\blank.htm"

    "RegisteredOwner"="Indonesian Today"
    "RegisterdOrganization"="We love peace"
    "OrgOrganization"="Underground Indonesian"
    "OrgOwner"="We love peace"

  2. Creates several batch files that run the next time you start Windows. When the batch files are run, they create the registry key:

    "<default>"="My Komputer"


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.

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
  1. Update the virus definitions.
  2. Run a full system scan and delete all the files detected as VBS.Terrosist. Replace the infected files from a clean backup, if required.

    The renamed files should have their original filenames restored. If your system's registered owner is "Indonesian Today," then delete the affected registry values.

For specific details on each of these steps, read the following instructions.

1. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

    The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

2. Scanning for and deleting the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with VBS.Terrosist, click Delete. Replace the infected files from a clean backup, if required.
  4. If the virus renamed Win.ini and System.ini, use Windows Explorer to rename Won.chk to Win.ini and System.chk to System.ini.
  5. If your system's registered owner is "Indonesian Today," then delete the affected registry values.

Writeup By: Atli Gudmundsson