Discovered: July 30, 2001
Updated: February 13, 2007 11:58:26 AM
Also Known As: Bloodhound.VBS.Worm, VBS.Potok.A [Computer Associat, VBS.Stream.A, VBS/Stream, VBS/Vdrive@MM, VBS/Potok@MM [McAfee], I-Worm.Potok [Kaspersky], VBS_POTOK.A [Trend], VBS/Potok-A [Sophos]
Type: Worm
Systems Affected: Windows

The VBS.Potok@mm worm is a simple Visual Basic script that exploits a little-known feature of Windows NT/2000 to spread. It sends itself to the first 50 recipients in the Microsoft Outlook Address Book. It attempts to add a new user to the infected computer and grant the user Administrator rights. The sample of this worm the Symantec AntiVirus Research Center (SARC) received has bugs that prevent it from operating correctly.

Antivirus Protection Dates

  • Initial Rapid Release version July 30, 2001
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version July 30, 2001
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date July 30, 2001

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

Technical Description

The worm exploits a little-known feature of Windows NT/2000: file streams. Under Windows NT/2000, a file can contain multiple streams of data. This is similar to a compressed archive file that contains multiple files. Each stream is accessible as an individual file. On a computer that is running Windows 95/98/Me with the FAT or FAT32 file system, these streams do not exist. Therefore, on a computer that is running Windows 95/98/Me, the worm is not able to run the parts of itself that attempt to add new users to the system.

The worm has four streams: a mail stream, a user stream, a main stream, and a group stream.

  • The mail stream attempts to send the worm to the first 50 recipients in the Microsoft Outlook Address Book.
  • The user stream attempts to create a new account on the system.
  • The main stream attempts to access the new account.
  • The group stream attempts to add the new user to the Administrator group.

The worm adds these four streams to a file named Odbc.ini that is created in the \Windows folder. It drops Notepad.vbs into the Winnt\System32\Ras folder. The file Go.vbs is also created in the Winnt\System32 folder.


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.


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. Delete any files that are detected as VBS.Potok@mm.
  3. If the file Odbc.ini is detected as infected, delete it.
  4. If a new, unrecognized Administrator account exists, delete the account.

Writeup By: Jimmy Shah