Trojan virus: How they work, and how to protect yourself

If there’s one thing we have to give cybercriminals credit for, it's their creativity. There are now many types of malware to track, and Trojans are among the most sneaky of them all. Here are the answers to all of your questions about Trojan viruses, plus how to get rid of a Trojan virus before you fall victim to one.


What is a Trojan virus?

A Trojan virus is a malicious piece of code, program or file that’s hidden or embedded within software. It’s packaged inside legitimate software, but download malware onto your device if you install them. In most cases, Trojan horses act to steal data or monitor your activities.

While this type of malware is known as a “Trojan virus,” it isn’t actually a virus. To get technical, a virus typically infects your device to corrupt files and trick you into sharing those files with others. It self-replicates and spreads, like a medical virus. On the other hand, Trojan programs operate alone. They need you to take some sort of action (like installing them) and affect one device at a time. That being said, they can be just as devastating as a virus, so it’s important to be vigilant.

You’re probably wondering: where did this term get its name? The Trojan Horse can be traced back to The Iliad, a Greek epic. In this poem, the warrior Odysseus builds a giant wooden horse to gift to his enemies, the Trojans. The catch? He hid his soldiers in the belly of the horse, and they crawled out during the night to capture the city of Troy.


What do Trojan viruses do?

In the cybersecurity world, Trojan malware seems to be harmless — and even useful — but really, it has a malicious agenda. Trojans are disguised as legitimate files, but they have one goal: to trick you into clicking, opening or installing them. If they’re successful, this triggers the Trojan to download malware onto your device or begin spying on you.

There are a few ways cybercriminals create Trojans, and phishing emails are the most common. For example, you might receive an email that appears to be from a trustworthy, reputable company. It looks authentic, so you have no issue opening the attachments. When you do, you essentially give the Trojan permission to activate, and it starts installing malicious code on your device.

Once a Trojan has gained access to your device, there’s really no limit to what it can do. Most Trojan hacks aim to take over control of your computer, tablet or smartphone, and send your data to another server. These are often known as “backdoor Trojans,” as they give cybercriminals a way to tap into your device without your knowledge.

Banking trojans are also common. This is when a Trojan monitors your online shopping or banking activities, and sends your credit card information to people looking to steal or profit from it. One of the most famous Trojans to date, the Zeus trojan, focused on stealing login credentials with great success.

These are a few other types of Trojan viruses:

  • Gaming or messaging trojans aim to steal your logins and access your data and other sensitive information.
  • Ransomware Trojans block access to your own data and threaten to publish or destroy it unless you pay a ransom.
  • DDoS Trojans rope your computer into a “botnet,” which is a network of devices that are remotely controlled by a hacker. Known as distributed denial of service (DDoS) attacks, these Trojans can restrict access to sites and other internet services.
  • Zero-day exploit Trojans harness a trusted software or hardware to infect your device with a threat that isn’t well-known yet.
  • Antivirus Trojans pretend to detect viruses on your device and try to scare you into paying for fake security software. Those payment details are then sent to the creator.

Signs of a Trojan attack

These include slow performance, freezing or crashing, or more unsolicited pop-ups than usual. You might notice changes to your desktop or browser, or find you’re being redirected to different sites.

Lock the gates with a good antivirus software

Just like the citizens of Troy invited the gift horse into their city, Trojans need your permission to run on your device.

A premium antivirus software like ESET Internet Security works like a security guard that turns the horse away and prevents it from entering your device. Along with Trojan virus removal, this software protects your devices from a host of cyber attacks, including ransomware and identity theft. It blocks offensive content and checks attachments and images for malware, and monitors any traffic trying to access your network.

If you’re running a business or have a little more room in your budget, ESET Protect Complete provides the same multi-layered defence against a range of cyber attacks and safeguards WiFI networks and webcams. It also protects your cloud email, collaboration and storage systems (like Google Drive), and offers endpoint protection. Questions? Contact us today to discuss the best security solutions for your needs.