VBS.Legal.A

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Discovered: January 16, 2001
Updated: February 13, 2007 11:59:11 AM
Type: Worm, Virus


VBS.Legal.A is a Visual Basic Script worm that copies itself to several folders on the hard disk and to a floppy disk if one is inserted in the floppy disk drive. The worm overwrites files with .vbs and .vbe extensions if they are located in the C:\Windows or C:\Windows\Samples folders.

Antivirus Protection Dates

  • Initial Rapid Release version January 16, 2001
  • Latest Rapid Release version August 20, 2008 revision 017
  • Initial Daily Certified version January 16, 2001
  • Latest Daily Certified version August 20, 2008 revision 016

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

Writeup By: Kaoru Hayashi

Discovered: January 16, 2001
Updated: February 13, 2007 11:59:11 AM
Type: Worm, Virus


When executed, the worm copies itself to the following locations:

  • C:\Windows\System
  • A:\

as one of the following files:
  • Important.doc.vbs
  • Notice.doc.vbs
  • Help.doc.vbs
  • Readme.doc.vbs
  • Readthis.doc.vbs.vbs
  • Legal.doc.vbs

It then adds itself as a value to the following registry entry:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

The worm also overwrites files that have .vbs and .vbe extensions if they are located in the C:\Windows or C:\Windows\Samples folders.

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.

Writeup By: Kaoru Hayashi

Discovered: January 16, 2001
Updated: February 13, 2007 11:59:11 AM
Type: Worm, Virus


To remove this worm, follow the instructions in the order shown.

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. If any files are found to be infected by VBS.Legal.A, write down the file name if it is located in C:\Windows\System or on a floppy disk, and then choose Delete.

    NOTE: If .vbs or .vbe files existed in the C:\Windows or C:\Windows\Samples folders, you will have to restore them from a backup.
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 and select the following subkey:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, look for a value that is the same as the file name that you wrote down in step 3 of the previous section.
  5. Select the value, press Delete, and then click Yes to confirm.
  6. Click Registry, and then click Exit to save the changes and close the Registry Editor.


Writeup By: Kaoru Hayashi