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How to know if my computer has a virus?

Luciano Mondragon

13.11.19 5 min. read

There are many different types of malware, computer viruses being one of them. Due to being one of the oldest types of malware, the term “computer virus” is often used as an umbrella term for all the different types of malware. So, the more accurate question would be “how to know if my computer has malware”.

But how can you know your computer has a virus or some other type of malware? If you have AV (antivirus) software, it should notice the malware already when encountering it. However, it is possible for malware to get through even though you have security programs.

Ok, so let’s forget about AV software for a minute. The types of malware differ in what they do, how they are executed and in how they are distributed. The difficulty of detection varies depending on the type of the malware. Some malware is meant to be detected, whereas others are intended to stay hidden for as long as possible.

Ransomware, adware and cryptojackers are easier to detect

Ransomware is very easy to detect because it will let you know of its existence. Unfortunately, when you find out, it’s usually too late. Ransomware encrypts all your data and asks for payment in return of the key to encrypt your files. You can get more information on ransomware and how to react if you get infected with it from here.

Adware is also quite easy to figure out. Are you seeing weird ads on your screen? You might have adware. Notice, though, that some programs and applications you have installed may show you ads without being malware. This applies especially to mobile devices, where many free applications show you ads when you use them. The ads that pop up on your screen when you are not using any application or program that is supposed to show ads are the ones you should be worried about. Adware also isn’t usually showing you offers from your local grocery store. Their ads include more questionable content, such as internet gambling and adult content.

Another type of malware that is somewhat easy to detect is coin miners aka cryptojackers. Cryptojackers generate cryptocurrency like Bitcoin using infected computers. This slows down the computer and uses internet connection. This generates heat and makes cooling fans create noise. You can also try to spot them in your task manager. If there are unknown processes running which take a lot of memory, they can be cryptojackers.

Viruses and worms can cause noticeable damage

Some malware, such as viruses and worms, can deal noticeable damage on your device, such as deleting files or interrupting processes. They can also show things on your screen. Any unwanted and unexecuted actions should raise suspicion. However, these can be spotted. Files are missing? Your device doesn’t work properly or keeps crashing? Are you getting weird warning pop ups, or is your antivirus program warning that it is disabled? Is your device suddenly running slower than it used to? These are all signs of possible infection. However, performance issues can have many other reasons too other than malware.

Spyware, banking trojans and rootkits try to stay hidden

Many types of malware are not so easily detectable, because they are designed to be stealthy and to avoid detection for as long as possible. Spyware is gathering information and login credentials from your device. Detecting and removing it would stop or prevent the attacker from gaining benefit from it. Banking trojans are also trying to get your information. More specifically your online bank login credentials.

Rootkits leave a backdoor to your system. This means it can be accessed from distance. This way your computer can be used for example as a part of a botnet. Botnets are used to carry out DDoS (Distributed Denial of Service) attacks. These types of malware are very hard to detect without antivirus software.

Antivirus software helps you detect if your computer has a virus

So how can you know if your computer has a virus or malware? The short answer is that without antivirus software, in most of the cases you can’t. Detecting malware without antivirus software can be very hard, even impossible. Many possible warning signs can be just something else. Kind of like having a headache can mean you are getting sick, your muscles are tense, or then you just didn’t drink enough water, or something else.

Our devices are very vulnerable to malware without antivirus software. Considering their importance, you probably don’t want them to be infected with anything. The best way to be safe from malware is to prevent your device from being infected in the first place. So, get a good antivirus program, like F-Secure’s award-winning SAFE which is included as part of F-Secure TOTAL, and keep your AV and your operating system up to date.





Luciano Mondragon

13.11.19 5 min. read


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