What is a Trojan Virus?

  • By David Lukic
  • Oct 08, 2020

Computers, the internet, and mobile devices make our lives easier and more fun, but they also come with some danger. The digital world is replete with viruses, malware, trojans, and other infections that can ruin your hardware and software as well as destroy your files, lock you out of your computer and take control of your network. You cannot be too careful when protecting yourself against this barrage of online threats.


How Does Trojan Virus Work?


A Trojan or Trojan horse virus is malware that mimics legitimate software, but when you execute it (download or install it), it infects your computer and wreaks havoc. Trojans are designed to take control of your computer, steal files, delete files, modify data, block things, copy files or data, and disrupt network connections as well as other nefarious actions. 


Viruses can self-replicate, but Trojans cannot. They also cannot run on their own; someone must initiate/execute the code to start them running. The term trojan horse virus comes from the story about the ancient city Troy and how the Greeks used a wooden horse filled with soldiers to take over the city. The Trojans took the horse as a trophy, but once inside the city gates, out flooded the army and won the Trojan War. 


A Trojan virus works the same way; it hides inside something that looks good but is really a digital infection waiting to happen.


Different Types of Trojan Horse Viruses


There are a few common types of Trojans to be aware of:

Trojan Horse Virus


Backdoor Trojans

This type of Trojan allows hackers to remotely access and control a computer, often for the purpose of uploading, downloading, or executing files at will.

Exploit Trojans

These Trojans inject a machine with code deliberately designed to take advantage of the weakness inherent to a specific piece of software.

Trojans Rootkit 

These Trojans are intended to prevent the discovery of malware already infecting a system so that it can affect maximum damage.

Banker Trojans

This type of Trojan specifically targets personal information used for banking and other online transactions.

Distributed Denial of Service (DDoS) Trojans

These are programmed to execute DDoS attacks, where a network or machine is disabled by a flood of requests originating from many different sources.

Downloader Trojans

These are files written to download additional malware, often including more Trojans, onto a device.”


Other Types of Trojan Horse Computer Virus


Fake AV Trojan

This is when you see a pop-up on your computer saying you have been infected by a virus and need to buy a cleaner right now, just click the link. These are designed to trick you into buying something you don’t need. The pop-up is the infection, not the cure.

Infostealer Trojan

This one does what it sounds like, it steals your information for financial gain or identity theft.

Ransomware Trojan

This nasty one locks your computer, encrypts all your data and demands a fee to unlock it all. 

Remote Access Trojan

This one gives the hacker complete control of your computer to spy on you or steal stuff. 

Mailfinder Trojan 

steals all your contacts’ information to use in spamming scams. 

SMS Trojan

this one works on mobile devices and intercepts your text messages; scary.

Trojan IM 

This trojan attacks IM platforms and takes over ownership of your account, sending malicious messages to your contacts.


This creepy one allows the cybercriminal to spy on you through your camera and microphone while also copying keystrokes to steal passwords and more!


Trojans are among the most damaging digital infections your device can get. They don’t only affect computers; they are also injected into legitimate apps, so when the user downloads and installs an app, their mobile device gets infected. That is alarming because most people carry a lot of data around in their phones.


An example of a particularly dangerous Trojan on the Android platform is called Switcher Trojan. Once infected, it attacks the user’s Wi-Fi network and uses it to commit crimes without them even knowing it!

What is a trojan virus


How to Detect a Trojan Virus


If your computer starts running really slow, or windows are popping up when you browse the internet, you may be infected. If programs start crashing or opening without your interaction, you may have a trojan horse virus. 


How to Remove Trojan Virus


Although these threats are numerous and challenging, there are things you can do to protect all your equipment. The number one way to combat these programs is using a reliable antivirus program, keeping it updated and running deep scans often. The best ones have built-in protection for ransomware, Trojans, malware, and even phishing attempts. Some other tips are:


  • Never download and install software unless it is from a trusted source.

  • Do not click links in email or download attachments. Even if it looks legitimate, if you weren’t expecting it, delete the email.

  • Keep your devices updated with the latest operating system and security patches.

  • Be sure to have antivirus software installed and run it frequently.

  • Use complex passwords on all your accounts. Don’t use the same ones on multiple websites and be sure to change them often.

  • Use a strong firewall on your home network and even consider installing a VPN to mask your IP address and online activities.

  • Backup your computer regularly. If you do get infected, you can restore your files with a good backup.

  • Stay away from sketchy websites and never download or install freeware.

  • Do not click on pop-ups in your browser or on your computer. 

These are some solid tips that, if used regularly, will keep you safe and your devices clean.

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