How to Remove a Trojan Horse From a Computer

Trojans are a nasty form of computer virus that are so named because they create a "back door" in the computer system by entering in another guise as a game, e-card or other email attachment. While not always malicious themselves, as viruses are, Trojans can allow hackers to enter your system and do serious damage. While the best way to avoid Trojans is to never download anything that doesn't come from a trusted source, infections happen. If your antivirus program suddenly pops up with the horrifying announcement that your computer has been infected by a Trojan horse, don't panic. Take these steps to remove it as quickly as possible.

Difficulty: Moderate

Instructions

Things You'll Need:

• Antivirus program

1. Update your antivirus software to the latest definitions. Viruses and Trojans are constantly being developed and mutated, so even if your antivirus software told you the Trojan was present, it's safest to ensure you have the most current virus definitions available.

2. Disable "System Restore" on your computer. This ensures that the Trojan is not accidentally backed up. The method for disabling System Restore will vary depending on what operating system you are using. In Windows XP go to the "Start" menu, right-click on "My Computer" and click "Properties." Click the "System Restore" tab, then turn off system restore.

3. Run your antivirus program. If the program finds the Trojan, allow it to quarantine and delete it. If the program finds the Trojan but is unable to delete it, restart the computer in Safe Mode, and rerun the antivirus program. This should allow you to remove the Trojan safely.

4. Restart the computer in normal mode and run another virus scan. If nothing is detected, re-enable System Restore.

5. Make sure your antivirus program has the necessary levels of resident protection for your computer. It should monitor your computer's file system, as well as email and network traffic, to prevent malicious software from entering your system. Avast and AVG are two often-recommended programs.

Tips & Warnings

• You can look up any particular Trojan on Symantec's Threat Explorer. The site tracks the most common current viruses and Trojans and offers specific removal instructions.
• Always keep a backup of your system. In case the Trojan does too much damage and can't be removed, you may need to reinstall your operating system.

Resources

• Symantec's Threat Explorer site
• AVG Anti-Virus
• avast antivirus
• The U.S. Computer Emergency Readiness Team article on recovering from a Trojan