Win32/Zafi is a family of mass-mailing worms. The worm sends itself to e-mail addresses that it finds on the infected computer. It may terminate processes that relate to system utilities and security products. It may change security-related registry key values. Some variants also copy the worm to network-share folders.

Threat behavior

When Win32/Zafi runs, it copies itself to %System% and creates a value in the registry key:
This value activates the worm when Windows starts.
The worm spreads primarily by sending itself as an attachment to e-mail addresses that it finds on the infected computer. Win32/Zafi terminates some processes that may relate to security products or Windows system utilities, for example Registry Editor or Task Manager. It may copy itself to network share folders on the infected computer.
Win32/Zafi may change security-related values in the following registry keys:
HKLM\SOFTWARE\Microsoft\Security Center


If your computer is infected by Win32/Zafi, you may not notice any symptoms, or you may notice crashes or slowdowns during normal operation. Your computer may be infected if you notice one or more of the following symptoms:
  • The following processes will not start:
    Windows Task Manager
    Windows Registry Editor
  • Presence of file %System%\Norton\Update.exe.
  • Presence of the following registry keys:


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: Jan 05, 2005
This entry was updated on: Sep 19, 2006

This threat is also detected as:
  • W32/Zafi@mm (McAfee)
  • W32.Erkez@mm (Symantec)
  • W32/Zafi@mm (Sophos)
  • W32/Zafi.Worm (Panda)