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Discovered: November 17, 2003
Updated: February 13, 2007 12:13:59 PM
Also Known As: Worm.Win32.Francette.a [Kasper, W32/Tumbi.worm [McAfee]
Type: Worm
Systems Affected: Windows
CVE References: CVE-2000-0884 CAN-2003-0352

W32.Francette.Worm is a worm that exploits the DCOM RPC vulnerability (described in Microsoft Security Bulletin MS03-026 ) using TCP port 135, as well as the Microsoft IIS Web Server Folder Traversal vulnerability (described in Microsoft Security Bulletin MS00-078 ). The existence of the file syshost.exe is an indication of a possible infection.

This worm is written in Borland Delphi and is packed with ASPack.

Antivirus Protection Dates

  • Initial Rapid Release version November 18, 2003
  • Latest Rapid Release version November 17, 2017 revision 034
  • Initial Daily Certified version November 18, 2003
  • Latest Daily Certified version November 18, 2017 revision 001
  • Initial Weekly Certified release date November 19, 2003

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

Writeup By: Scott Gettis

Discovered: November 17, 2003
Updated: February 13, 2007 12:13:59 PM
Also Known As: Worm.Win32.Francette.a [Kasper, W32/Tumbi.worm [McAfee]
Type: Worm
Systems Affected: Windows
CVE References: CVE-2000-0884 CAN-2003-0352

When W32.Francette.Worm is executed, it performs the following actions:

  1. Adds the values:

    "Microsoft IIS"="syshost.exe"

    to the registry key:


  2. Calculates a random IP address.

  3. Attempts to connect to the randomly generated IP addresses.

  4. Once the worm identifies a computer as being active on the network, it sends data to TCP port 135, which exploits the DCOM RPC vulnerability.

  5. Then, it creates a remote shell on the vulnerable host and instructs the victim computer to use FTP to connect to a ftp server whose address is hard-coded into the worm.

  6. Downloads an updated version of itself as syshost.exe and executes it on the remote machine.
  7. Uses the Microsoft IIS Web Server Folder Traversal vulnerability to exploit unpatched servers running IIS, in order to download the following files to the C:\Winnt\System32 folder:
  8. Connects to a specific IRC channel on a specific IRC server on TCP port 6669 or 6667 to receive remote instructions to:
    • Perform Denial of Service (DoS) Attacks
    • Execute commands
    • Download files
    • Scan for open ports on remote machines
    • Flood IRC channels


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: Scott Gettis

Discovered: November 17, 2003
Updated: February 13, 2007 12:13:59 PM
Also Known As: Worm.Win32.Francette.a [Kasper, W32/Tumbi.worm [McAfee]
Type: Worm
Systems Affected: Windows
CVE References: CVE-2000-0884 CAN-2003-0352

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. Do one of the following:
    • Windows 95/98/Me: Restart the computer in Safe mode.
    • Windows NT/2000/XP: End the Trojan process.
  4. Run a full system scan and delete all the files detected as W32.Francette.Worm.
  5. Reverse the changes that the Trojan made to the registry.
For specific details on each of these steps, read the following instructions.

1. Disabling 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. 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.

3. Restarting the computer in Safe mode or ending the Trojan process
    Windows 95/98/Me
    Restart the computer in Safe mode. All the Windows 32-bit operating systems, except for Windows NT, can be restarted in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."

    Windows NT/2000/XP
    To end the Trojan process:
    1. Press Ctrl+Alt+Delete once.
    2. Click Task Manager.
    3. Click the Processes tab.
    4. Double-click the Image Name column header to alphabetically sort the processes.
    5. Scroll through the list and look for Cnqmax.exe.
    6. If you find the file, click it, and then click End Process.
    7. Exit the Task Manager.
4. 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 W32.Francette.Worm, click Delete.

5. Reversing the changes made to the registry

WARNING: 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, and then click Run. (The Run dialog box appears.)
  2. Type regedit

    Then click OK. (The Registry Editor opens.)

  3. Navigate to the key:


  4. In the right pane, delete the value:

    "Microsoft IIS"="syshost.exe"

  5. Exit the Registry Editor.

Writeup By: Scott Gettis