VBS.Network.C

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Discovered: April 07, 2000
Updated: February 13, 2007 11:35:28 AM
Type: Worm


This variant of VBS.Network places an illegally altered version of a legitimate program, distributed.net, on the computer.


There are other things that you can do to protect your system from this type of Trojan Horse.

Scripting Host precautions
VBS.Network.C, and others such as the Wscript.KakWorm, use the VBScript computer language to run.

  • If you are using Norton AntiVirus 2001, a free program update is available that includes Script Blocking is available.Please run LiveUpdate to obtain this.
  • For other versions of Norton AntiVirus, SARC offers a tool to disable the Windows Scripting Host.

Configure Windows for maximum protection
Because this virus spreads by using shared folders on networked computers, to ensure that the virus does not reinfect the computer after it has been removed, Symantec suggests sharing with read-only access or using password protection. For instructions on how to do this, see your Windows documentation or the document How to configure shared Windows folders for maximum network protection .

Antivirus Protection Dates

  • Initial Rapid Release version April 07, 2000
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version April 07, 2000
  • Latest Daily Certified version September 28, 2010 revision 036

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

Writeup By: Keith Smith

Discovered: April 07, 2000
Updated: February 13, 2007 11:35:28 AM
Type: Worm


VBS.Network.C also attempts to copy itself across a network by first locating shared network drives and then mapping them to a local drive letter. Once a Windows 95/98/NT drive is infected, the worm tries to copy itself to the StartUp folder of the drive to ensure execution at startup. The worm remains in memory until the system is restarted.

This variant of VBS.Network places the following two files in the C:\Windows folder:

  • Dnetc.exe
  • Dnetc.ini

These are modified versions of the distributed.net program. The presence of these files alone is not an indication of infection. These files can legitimately reside on the computer without having been placed there by VBS.Network.C. In addition, the Network.vbs file may be copied to one or more locations, including the root folder, \Windows, \Windows\System, and \Windows\Start Menu\Programs\StartUp.

For additional information on distributed.net, the legitimate program that has been illegally altered to do this, see the document What is distributed.net

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: Keith Smith

Discovered: April 07, 2000
Updated: February 13, 2007 11:35:28 AM
Type: Worm


Follow these steps to delete the VBS.Network files from your computer:

  1. Click Start, point to Find, and then click Files or Folders.
  2. Make sure that Look in is pointing to the C: drive and the Include subfolders is checked.
  3. Type network.vbs in the Named box, and then click Find Now.
  4. Select any files that are found, and then delete them.

    NOTE: If you have the Windows Scripting Host installed, it comes with the sample file, Network.vbs. This file is not infectious. It is commonly found in the C:\Windows\Samples\Wsh folder. It is not necessary to delete this file, but doing so will not harm the system. File names alone are not enough to determine if a file is clean or malicious.
  5. Type network.log in the Named box, and then click Find Now.
  6. Delete the file if it is found. It will usually be on the root of your C drive.
  7. Click New Search, and then click OK to confirm.
  8. In the Named box, type--or copy and paste--the following file names:

    dnetc.exe dnetc.ini
  9. Click Find Now. Windows will find all copies of the file that are located on the C drive.

    CAUTION: You are about to delete files. Make sure that your read the following information before you do so: Dnetc.exe is a legitimate distribution program that has been illegally altered to distribute this worm. Unless you are sure that the files that are found are needed, legitimate versions of this program, it is strongly recommended that you delete them. For additional information on distributed.net, the legitimate program which has been illegally altered to do this, see the document What is distributed.net
  10. In the lower pane of the Find dialog box, select the files that you want to remove. It is recommend that you do this one at a time.
  11. Press Delete, and then click Yes to confirm.
  12. Click New Search, and then click OK to confirm.
  13. Type network.vbs in the Named box, and then click Find Now.

    NOTE: If you have the Windows Scripting Host installed, it comes with the sample file, Network.vbs. This files is not infectious. It is commonly found in the C:\Windows\Samples\Wsh folder. It is not necessary to delete this file, but doing so will not harm the system. File names alone are not enough to determine whether a file is clean or infectious.
  14. Select any files that are found, (with the exception of the Scripting Host sample file in the C:\Windows\Samples\Wsh folder), and then delete them.
  15. Click New Search, and then click OK to confirm.
  16. Type microsoft_office.ink in the Named box, and then click Find Now.
  17. If this file exists, then it will be in the StartUp folder. It is a shortcut file and should be deleted.
  18. Close the Find Files window.
  19. Right-click the Recycle Bin icon on your desktop, and then click Empty Recycle Bin.
  20. Restart the computer.
  21. Start NAV and run a full system scan.

Writeup By: Keith Smith