Trojan Viruses: What You Need to Know

TL;DR

Yes, Trojan horse programs are a type of cyber security threat. They disguise themselves as legitimate software to trick you into installing them, then perform malicious actions. This guide explains what they are, how they spread, and how to protect yourself.

What is a Trojan Horse Virus?

A Trojan horse (often just called a ‘Trojan’) isn’t technically a virus in the traditional sense. Viruses replicate themselves and spread automatically. Trojans don’t usually self-replicate. Instead, they rely on tricking you into running them.

• Disguise: They pretend to be something useful – a game, an update, or even a security tool.
• Malicious Actions: Once installed, they can do anything the attacker wants: steal data, install other malware, control your computer remotely, encrypt files for ransom (ransomware is often delivered via Trojans), etc.

How Do Trojans Spread?

Trojans get onto your system in various ways:

1. Email Attachments: The most common method. Be very cautious about opening attachments from unknown senders, even if the email looks legitimate.
2. Malicious Downloads: Downloading software from untrusted websites or peer-to-peer networks.
3. Infected Websites: Visiting compromised websites that automatically download malware.
4. Social Engineering: Attackers tricking you into installing the Trojan through deception (e.g., fake updates, urgent warnings).

How to Protect Yourself

Here’s a step-by-step guide to staying safe:

1. Install Anti-virus Software: A good anti-virus program is your first line of defence. Make sure it’s up-to-date.
   • Popular options include Bitdefender, Norton, McAfee, and Kaspersky (research to find one that suits you).
   • Enable real-time scanning for immediate threat detection.
2. Keep Your Software Updated: Updates often include security patches that fix vulnerabilities Trojans exploit.
   • Windows: Go to Settings > Update & Security > Windows Update and check for updates regularly.
   • macOS: System Preferences > Software Update.
   • Applications: Regularly update your browsers, plugins (like Adobe Flash – if you still use it!), and other software.
3. Be Careful with Email Attachments: Never open attachments from unknown senders or unexpected emails.
   • Even if the sender seems familiar, verify their identity before opening anything.
4. Download Software Only From Official Sources: Avoid downloading software from unofficial websites or peer-to-peer networks.
   • Always download directly from the developer’s website.
5. Use a Firewall: A firewall blocks unauthorized access to your computer.
   • Windows has a built-in firewall (Control Panel > System and Security > Windows Defender Firewall). Ensure it’s enabled.
6. Be Wary of Suspicious Links: Don’t click on links in emails or websites that look suspicious.
   • Hover over the link to see where it actually leads before clicking (but be aware attackers can mask URLs).
7. Use Strong Passwords and Two-Factor Authentication: This makes it harder for attackers to access your accounts even if they steal your password.

What If You Think You’re Infected?

If you suspect a Trojan infection:

1. Run a Full System Scan: Use your anti-virus software to perform a complete scan of your computer.
2. Disconnect From the Internet: This prevents the Trojan from communicating with its command and control server.
3. Consider Using a Malware Removal Tool: Tools like Malwarebytes can help remove stubborn infections.

   malwarebytes --scan

4. Reinstall Your Operating System (Last Resort): If all else fails, reinstalling your OS is the most thorough way to get rid of a Trojan. Back up your important data first!