Win32/Zindos is a worm that targets computers running the following Microsoft Windows 9x, Windows ME, Windows NT, Windows 2000, and Windows XP. The worm spreads to computers that are already infected by the mass-mailer worm Win32/Mydoom.O@mm. Win32/Zindos may perform a denial of service (DoS) attack against certain Web sites.

Threat behavior

The Win32/Zindos worm spreads through a backdoor that is created by the mass-mailer worm Win32/Mydoom.O@mm. The backdoor then runs Win32/Zindos. When Win32/Zindos runs, it adds a value to registry key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run. The registry value contains the worm path, so that the worm runs whenever Windows starts. The worm may create multiple threads to launch denial of service (DoS) attacks against certain Web sites.


You may notice system performance degradation and slower network connectivity if your computer is infected by Win32/Zindos.


Take the following steps to help prevent infection on your system:
  • Enable a firewall on your computer
  • Get the latest computer updates
  • Use up-to-date antivirus software
  • Use caution with unknown attachments

Enable a firewall on your computer

Use a third-party firewall product or turn on the Microsoft Windows XP Internet Connection Firewall.
To turn on the Internet Connection Firewall in Windows XP
  1. Click Start, and click Control Panel.
  2. Click Network and Internet Connections, and click Network Connections. If you do not see Network and Internet Connections, click Switch to Category View.
  3. Highlight a connection that you want to help protect, and click Change settings of this connection.
  4. Click Advanced, and select Protect my computer and network by limiting or preventing access to this computer from the Internet.
  5. Click OK.

Get the latest computer updates

Updates help protect your computer from viruses, worms, and other threats as they are discovered. You can use the Automatic Updates feature in Microsoft Windows XP to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
To turn on Automatic Updates
  1. Click Start, and click Control Panel.
  2. Click Performance and Maintenance. If you do not see Performance and Maintenance , click Switch to Category View.
  3. Click System.
  4. Click Automatic Updates, and select Keep my computer up to date.
  5. Select a setting. Microsoft recommends selecting Automatically download the updates, and install them on the schedule that I specify and setting a regular update time.
  6. If you choose to have Automatic Updates notify you in step 5, you will see a notification balloon when new downloads are available to install. Click the notification balloon to review and install updates.

Use up-to-date antivirus software

Most antivirus software can detect and prevent infection by known malicious software. You should always run antivirus software on your computer that is updated with the latest signature files to automatically help protect you from infection.

Use caution with unknown attachments

Use caution before opening unknown e-mail or IM attachments, even if you know the sender. If you cannot confirm with the sender that a message is valid and that an attachment is safe, delete the message immediately, and run up-to-date antivirus software to check your computer for viruses.

Alert level: Severe
This entry was first published on: Dec 10, 2004
This entry was updated on: Sep 19, 2006

This threat is also detected as:
  • Zindos (F-secure)
  • WORM_ZINDOS (Trend Micro)
  • W32/Zindos.worm (McAfee)
  • W32.Zindos (Symantec)
  • Win32/Zindos (CA)