Worm:Win32/Zotob.E is a network worm that targets computers running certain versions of Microsoft Windows. The worm spreads by exploiting the Windows Plug-and-Play vulnerability described in Microsoft Security Bulletin MS05-039. The worm has a backdoor component that connects to an IRC server from the infected computer to receive commands from attackers.

What to do now

To manually recover from infection by Worm:Win32/Zotob.E, follow these steps:
  1. Install security update MS05-039.
  2. Disconnect from the Internet.
  3. End the worm process.
  4. Delete the worm files from your computer.
  5. Delete the worm registry entries.
  6. Restart your computer.
  7. Take steps to prevent re-infection.

Install security update MS05-039

To install MS05-039 using Windows Update
  1. Go to the Windows Update Web site at
  2. On the Windows Update site, click Scan for Updates. Windows Update scans your computer and returns a list of critical updates, including service packs.
  3. In the Pick updates to install list, click Critical Updates and Service Packs. Windows Update creates a list of the updates appropriate for your computer, including MS05-039 if it is not installed. Critical updates are selected for download automatically.
  4. Click Review and install updates, and then click Install Now. You may need to restart your computer after installing the updates.

Disconnect from the Internet

To help ensure that your computer is not actively infecting other computers, disconnect it from the Internet before proceeding. Print this Web page or save a copy on your computer; then unplug your network cable and disable your wireless connection. You can reconnect to the Internet after completing these steps.

End the worm process

Ending the worm process will help stop your computer from infecting other computers as well as resolve the crashing, rebooting, and performance degradation issues caused by the worm.
To end the worm process
  1. Press CTRL+ALT+DEL once and click Task Manager.
  2. Click Processes and click Image Name to sort the running processes by name.
  3. Select the process wintbp.exe, and click End Process.

Delete the worm files from your computer

To delete the worm files from your computer
  1. Click Start, and click Run.
  2. In the Open field, type the name of the system folder, for example, C:\Winnt\system32\
  3. Click OK.
  4. Click Name to sort files by name.
  5. If wintbp.exe is in the list, delete it.
  6. On the Desktop, right-click the Recycle Bin and click Empty Recycle Bin.
  7. Click Yes.
If deleting the files fails, follow these steps to verify that wintbp.exe is not running:
  1. Press CTRL+ALT+DEL once and click Task Manager.
  2. Click Processes and click Image Name to sort the running processes by name.
  3. Confirm that wintbp.exe is not in the list.

Delete the worm registry entries

Worm:Win32/Zotob.E creates entries in the Windows registry that attempt to run the worm every time your computer restarts. These entries should be deleted.
To delete the worm registry entries
  1. On the Start menu, click Run.
  2. Type regedit and click OK.
  3. In the left pane, navigate to the key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    In the right pane, right-click the following value, if it exists:
  4. Click Delete and click Yes to delete the values.
  5. Close Registry Editor.

Restart your computer

To restart your computer
  1. On the Start menu, click Shut Down.
  2. Select Restart from the drop-down list and click OK.

Take steps to prevent re-infection

Do not reconnect your computer to the Internet until the computer is protected from re-infection. See the "Preventing Infection" section for more information.

Threat behavior

Worm:Win32/Zotob.E takes the following actions:
  • Copies itself to <system folder>\wintbp.exe.
  • Makes the following registry key changes. These changes cause the worm to run each time Windows starts.
    • Adds value: wintbp.exe
      with data: wintbp.exe
      in registry key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  • Scans randomly generated IP addresses on port 445. If a connection is established, the worm sends exploit code to the computer. If the computer is running Windows 2000 and does not have MS05-039 installed, the exploit code causes the exploited computer to download a copy of the worm using TFTP and runs the worm on the exploited computer.
  • Connects to an IRC server to receive commands, which can include:
    • Retrieving system information such as CPU speed, memory usage, Windows operating system,  connection type, IP address, and Windows logon information.
    • Downloading and running files using http.
    • Removing the worm.


There are no readily apparent indications that your computer is infected with Worm:Win32/Zotob.E. However, your computer may be infected with Worm:Win32/Zotob.E if you notice any of the following symptoms:
  • Presence of <system folder>/wintbp.exe
  • Presence of value: wintbp.exe
    with data: wintbp.exe
    in the following registry keys:
  • Excessive network traffic over port 445


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.

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 in Windows XP
  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. If you don't have antivirus software installed, you can get it from one of several companies. For more information, see

Alert level: Severe
This entry was first published on: Aug 16, 2005
This entry was updated on: Sep 19, 2006

This threat is also detected as:
  • W32.Zotob.E (Symantec)
  • W32/IRCbot.worm!MS05-039 (McAfee)
  • WORM_RBOT.CBQ (Trend Micro)
  • Bozori.A (F-secure)
  • W32/Tpbot-A (Sophos)