Win32/Optix is a family of highly configurable backdoor Trojans that targets several versions of Microsoft Windows. The Trojan opens a backdoor that allows an attacker to control an infected computer remotely. It can also release system information to an attacker and disable security-related and other programs. 

Threat behavior

When Win32/Optix runs, it can take the following actions:
  • Modify the Windows registry so that the Trojan runs each time Windows starts.
  • Create a copy of itself in a location that the Trojan specifies in a registry key.
  • Disable security-related and other programs.
  • Display false error messages.
  • Run programs that it downloads from a Web site.
  • Send infection notifications to an attacker using an instant messaging program or a Web page.
Win32/Optix can open a backdoor that can be used to:
  • Terminate processes.
  • Run programs remotely.
  • Download programs from a Web site.
  • Release system information to an attacker.


Win32/Optix infection symptoms vary because attackers can customize the actions of this Trojan. 


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: Jun 27, 2005
This entry was updated on: Sep 19, 2006

This threat is also detected as:
  • Backdoor/Optix (CA)
  • Backdoor.Optix (Symantec)