Discovered: June 04, 2003
Updated: February 13, 2007 12:25:39 PM
Type: Worm
Systems Affected: Windows

W32.Randex is a detection for a family of worms that spreads through file-sharing.

W32.Randex can perform different backdoor-type functions, by connecting to a configurable IRC server and joining a specific channel to listen for instructions.

Newer variants may also spread by exploiting the following vulnerabilities:

Antivirus Protection Dates

  • Initial Rapid Release version June 05, 2003
  • Latest Rapid Release version July 16, 2019 revision 023
  • Initial Daily Certified version June 05, 2003 revision 003
  • Latest Daily Certified version July 17, 2019 revision 001
  • Initial Weekly Certified release date June 05, 2003

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

Technical Description

When W32.Randex is executed, it does the following:

  1. Copies itself to the %System% folder.

    : %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  2. Calculates a random IP address for a computer to infect.

  3. Attempts to authenticate itself to the IP addresses using weak passwords.

    For example:
    • pass
    • password
    • computer
    • 12345

  4. If successful, the worm copies itself as:
    • ipc$
    • C$
    • Admin$

  5. Schedules a Network Job to run the worm.

  6. Can be configured to perform Denial of Service (DoS) attacks on specified servers.

  7. Can be configured to terminate security product processes.

  8. Connects to specified IRC servers and joins a channel to receive commands.

  9. Adds a variable registry value to one or more of the following registry keys:





    For example:

    "superslut" = "msslut32.exe"

  10. May steal the CD keys of games, such as:

    Battlefield 1942 The Road to Rome
    Battlefield 1942 Secret Weapons of WWII
    Unreal Tournament 2003
    Found Half-Life

  11. May send personal information, such as the operating system, IP address, user name, and so on, to the IRC server.

  12. May open a backdoor port.

  13. May download the file from the Internet and update itself.

  14. May spread by exploiting the following vulnerabilities:


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.


Before you begin :
Newer variants of the worm take advantage of several Windows vulnerabilities so you must patch for these vulnerabilities described above. If you do not, it is likely that your computer will continue to be re-infected.

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Disable System Restore (Windows Me/XP).
  2. Update the virus definitions.
  3. Restart the computer in Safe mode or VGA mode.
  4. Run a full system scan, and then delete all the files that are detected as W32.Randex.
  5. Delete the value that was added to the registry.
For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation or one of the following articles:
For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder ," Article ID: Q263455.

2. To update the virus definitions
Symantec Security Response fully tests all 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.

3. To restart the computer in Safe mode or VGA mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.
  • For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
  • For Windows NT 4 users, restart the computer in VGA mode.

4. To scan for and delete 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 W32.Randex, write down the file names, and then click Delete.

5. To delete the value from the registry

Important: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
  1. Click Start > Run.
  2. Type regedit

    Then click OK.

  3. Navigate to the key:


  4. In the right pane, delete any values that refer to the file name that was detected as infected with W32.Randex.

  5. Navigate to the following key:


  6. In the right pane, delete any values that refer to the file name that was detected as infected with W32.Randex.

  7. Do one of the following:
    • If you are using Windows NT/2000/XP, skip to step j.
    • If you are using Windows 95/98/Me, proceed with step h.

  8. Navigate to the following key:


  9. In the right pane, delete any values that refer to the file name that was detected as infected with W32.Randex.

  10. Navigate to the following key:


  11. In the right pane, delete any values that refer to the file name that was detected as infected with W32.Randex.

  12. Exit the Registry Editor.

  13. Restart the computer in Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."

Writeup By: Kaoru Hayashi