How to Find & Remove a Trojan Virus from your Computer


The term “Trojan virus” can refer to a broad spectrum of different virus types, but they all share one thing in common – the delivery method. Like the Trojan Horse of the ancient Greeks, a Trojan virus hides itself, typically within a legitimate software. When the user installs the software, that’s when Odysseus and the boys jump out, ready to cause mayhem.

Trojan viruses are most commonly obtained from downloading pirated software, but not always. Sometimes reputable download sites can accidentally host malware infected files, because of a light screening process. We’re not going to drop names, but it’s entirely possible to download a legitimate copy of trial software from a software hosting website, only to find that the software has infected you with malware like PUPs (potentially unwanted programs) or other little critters.

How to find and detect a Trojan virus

Okay, so here’s the thing. We already discussed that “Trojan virus” actually refers to the delivery method, so you’re not actually hunting for a Trojan virus. You’re hunting for any kind of virus that was delivered through the Trojan method. Got it?

So you need to be aware of the most common symptoms of your computer being infected with malware, any kind of malware. That’s a pretty broad range of definitions, so we’ll list some of the most common.

  • Significant computer slowdown: Some unwanted app or program running in the background. Could be a Cryptominer if you notice unusually high CPU usage, but basically, something unwanted is running in the background.
  • Popup ads on your desktop: This is a classic virus symptom, basically your computer will start displaying a lot of popup ads even on your desktop. It’s sort of fallen out of popularity with cybercriminals though, especially since its an immediate sign that your computer has been infected.
  • Apps you don’t remember installing: These are classic PUPs (potentially unwanted programs), which can be bundled along with the installation of the software you actually wanted. Nowadays, most installers ask if you want to optionally install these additional programs, but not always.
  • Browser homepage changed: If the homepage of your browser was changed, it’s definitely a sign of either a rogue browser extension, or some other kind of malware.
  • Unusual network traffic: If you open Task Manager (or the Linux and Mac equivalent) and notice unusual network traffic, such as a lot of outgoing data even when you aren’t actually doing anything related to the internet, that’s a good sign that something fishy is going on.
  • Files or folders that can’t be deleted: If you notice some new files or folders you don’t remember creating, and you try to delete them only to be told that these files are “already in use”, that’s classic virus activity. Those files are probably related to the first thing on this list we mentioned.
  • Antivirus won’t launch: Many viruses have built-in defense mechanisms to either disable your antivirus, or completely prevent it from launching. If your antivirus will not launch, or cancels unexpectedly in the middle of a scan, that’s classic virus symptom.
  • You can’t search about antivirus: Some viruses will actually prevent you from searching the internet about antivirus or other cybersecurity topics. The virus will redirect your browser when you try to visit websites for antivirus software.
  • Keyboard layout changed or incorrect letters: Viruses can delete or alter important system files, which can cause problems with your computer hardware. This isn’t typically desired by cybercriminals, as it will alert the user to the presence of a virus, but it still happens. If your keyboard layout suddenly changes, or types the wrong characters, it may be a problem with the keyboard itself. But if you swap out the keyboard and still experience the issue, it’s a sign of some type of malware infection that has affected files relevant to hardware.

Removing the virus from your computer

First, you need to think of any software you recently installed. Using a tool like CCleaner, you can organize the software installed on your computer by most recently installed. You should carefully scan this for anything you don’t remember installing.

Running a virus scan should take care of the problem in most situations, but some viruses can be particularly stubborn. Especially those viruses that have managed to corrupt your antivirus software. In this situation you’ll need to roll up your sleeves and get a little dirty.

You may need to try booting your computer into Safe Mode, and running the antivirus software from there. Also try Safe Mode without networking, to prevent the virus from communicating with its home base.

If your antivirus still refuses to launch in Safe Mode, you’ll probably need an antivirus rescue disk. This is a bootable antivirus, meaning it runs the antivirus scan without actually launching your operating system. There are many available, but if your computer is already infected, it may be almost impossible to download the tool and create a bootable disk from it. In this case, you’ll need a second computer.

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