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Computer Virus Types: Cybersecurity Guide [Definitions & Removal]

What are the main computer virus types? What are the names of all virus types? What is the definition of each virus? How to remove viruses and protect yourself?

What Is a Computer Virus?

А computer virus is a specific type of malicious software, but most users generally refer to infections or viruses. In fact, a virus is a type of program that upon execution replicates itself by modifying other programs and inserting its own code. Once the replication happens, the affected areas become “infected” with the computer virus.

Viruses are becoming increasingly diverse in types. From simple dangers that are harmless and made to mock people for their poor cyber-security or heighten the ego of some teenage hacker, they have become the sole reason why there are so many attacks and breaches in organizations and network security. Furthermore, cyber threats have become so serious that one specific computer virus can have the potential to disrupt major facilities of the government and even atomic energy facilities. And now with the variety of devices increasing out there, it is important to know how the different types of infections work and how to protect yourself from then. Since it becomes harder for the regular user to keep track of such diversity, we have decided to separate the infections into several main categories and provide explanations for each.

Browser Redirect Virus Threats

ads-redirects-sensorstechforumBrowser Redirection threats as they are called are basically the pesky PUA (Potentially Unwanted Application) we explained earlier. A browser redirect as a computer virus is not technically infections but because of their nagging and persistent behavior, affected users refer to them as cyber threats.

These forms of redirects could be seen in multiple different places on your computer – as a program installed on it, attached to a legitimate program or even by being attached to a browser extension or be the browser add-on itself. They can cause a lot of browser redirects on your computer that can lead to seriously risky sites. These sites could turn out to be:

  • Scam sites.
  • Infected sites.
  • Phishing pages.

Browser redirects may come onto victims’ computers by being bundled to the installers of other programs or if the victim downloads them. These types of bundling operations can include the browser redirection threat to seem like a “free extra” or an “optional offer” that is added as a bonus to the program you are currently trying to install. Once the programs of this type are added, they can immediately begin to slow your computer down with redirects and pesky pop-ups. Not only this, but these apps often use different tracking technologies to obtain key data. This is done with the primary goal to slither ads that target you with the same things you search for or with your location in order to increase the likelihood of you clicking on the suspicious ad.

These types of scam dangers could be a dubious software, that aims to detect a lot of different errors that do not exist, like rogue apps, and try to get you to pay a lot of money for a full license. Scam as a computer virus can appear as a web page that is brought to your computer as a result of browser redirection. These web pages lock your browser and pretend that there is some sort of an error in it, aiming to get you to call a fake tech support number, whose primary purpose seems to be to scam you. Once called, the scammers aim to convince you to let them in your computer and fix the issues, and for that they want you to pay hundreds of dollars and there may not be any issues after all. Not only this, but there are other forms of scam pages as well, which many call phishing. They may be displayed on your computer as a result of being infected by a dangerous Trojan that is detecting each time you visit a bank site or a large social media or e-mail service, like Facebook or Gmail. Then, the threat causes a redirect to phishing (fake) web page, that looks very close or identical to the original page. The main idea behind this is for you to type in your credit card information or login details and for the cyber threat to steal them. This is why you should always be very careful where you type your data and check if the link in the address bar is the original site or no.

Trojan Infections

trojan-horses-sensorstechforumTrojans are by far one of the oldest and most widely used type of spyware tools out there. They enter your computer silently by exploiting vulnerabilities in your system, but in contrast to other dangers these types of dangers aim to remain as silent as possible, causing no symptoms. What Trojans do is absolutely anything you can imagine a threat to do. The main activities of a Trojan involve:

  • Logging the keys you type on your keyboard.
  • Tracking your camera and microphone.
  • Obtain files.
  • Download other infections.
  • Update itself.
  • Take remote control over your mouse.
  • Stop key Windows processes.
  • Create copies of itself to trick you that you have successfully removed it.

In addition to this, the main idea of this computer malware is to act as a remote control to your computer. This means that every action you do is monitored and your best bet is to simply change all your passwords after removing the Trojan.

You should also be warned of the dangers of various trojanized apps that can be downloaded freely from the Internet. Such a recent example is the trojanized version of the AnyDesk app.

Android Virus Threats

android viruses

Android viruses are relatively among the new forms of malware that exist in the modern history of computer viruses. There have been all kinds of malicious software and PUAs (potentially unwanted applications) for Android and the methods of infection that they have used to slither on Android cellphones and tablets that have most often been noticed by researchers are as follows:

  • Via third-party apps, downloaded outside of Google PlayStore.
  • Via malicious links sent on chat clients, like Messenger, Telegram, WhatsApp, Viber, etc.
  • Through ads or corrupted posts on social media that cause redirects to malicious URLs.
  • Via infected Wi-Fi networks.
  • Via malicious SMS messages.
  • Via malicious drives (if the victim is targeted).

Given these methods of attacks, the viruses for Android have become more in terms of variety, and some of the most recently seen of those are:

What is very interesting about those viruses is that they all used different types of Android vulnerabilities and zero-day bugs that have been detected shortly after or before most of the infections were seen in circulation.

iPhone or iPad (iOS) Virus Threats

iPhone virus

Another target to hackers is the iOS platform that supports iPhones and iPad devices, even though the infections were much less and count and much more controllable, due to the nature of how the OS is built. This does not stop malware authors to create iPhone viruses nonetheless. Here we have seen mostly different types of pop-ups and scam messages, some of which were able to even manipulate the iOS Calendar App to flood the device with notifications that may contain some very nasty and malicious URLs.

In fact, there have been countless of “Calendar Virus” threats and iPhone browser hijackers out there, residing under different URLs, such as:

Other than that, iPhones and iPads have also seen their share of spam scam notifications to appear as browser redirects as well, such as:

These were particularly dangerous, because in the case of inexperienced users they often tend to lead to tech-support scammers or fishing webpages that are designed to steal financial or personal information in the form of a webpage that asks for your details to win a prize or fix your iPhone in a specific way.

Mac Virus Threats

apple-logo-sensorstechforumViruses on Mac have started to become increasingly more and more dangerous to users. Infections authors have proven once again that they can create quite the Mac Viruses and use those to their advantage. So far there have been different types of threats for Mac out there:

Mac Ransomware – locks your Mac or encrypts your files, making them unopenable, holding your Mac hostage until you pay ransom in BitCoin.
Mac Trojans – there have been numerous cases of Mac Trojans out there, most of which related to banking threats aiming to steal banking details.
Mac Adware and Redirects – these types of “viruses” for Mac are the most common. They aim to get victims to see a lot of different advertisements.
Rogue apps for Mac – these types of fake fixers, optimizers and antivirus programs often aim to get you to visit a third-party site to buy their licenses, that are in the hundreds of dollars. They pretend to find errors on your Mac that do not exist to motivate you into getting their full version to remove them.

Usually, the most widespread infections on Mac are the browser extensions, adware and browser redirect PUAs (Potentially Unwanted Applications). They often come bundled alongside other programs and they may introduce a variety of ads on your Mac, such as pop-ups, redirects, push notifications, changes the default search engine that displays ads instead of search results, etc. The end goal of those pesky programs is to lead you to third-party websites and those sites could eventually turn out to be scam sites and even cyber threat sites that can slither a more serious threat in your Mac.

Ransomware Threats

ransomware-threat-sensorstechforumAccording to latest statistics, ransomware threats have become notoriously popular up to the point that they are now the most money-generating type of cyber-threat out there. This is because a ransomware as a computer virus is basically an extortion scheme for your files.

Is ransomware in fact a form of malicious software? It can be. If the ransomware prevents its victims from accessing their files, it is in fact a malicious software. The very first case of a ransomware attack was in its essence a computer virus attack. Current ransomware threats are more similar to computer worms because they can spread across systems and networks without the need for user interaction. An example of such a case is the infamous WannaCry outbreak. A more recent example is the attack against Kaseya.

Generally speaking, the ransomware operator’s sole purpose is to make sure that your files could not be opened by using the same encryption that is used to cover up and hide different types of sensitive files. Such encryption scrambles your files and makes them no longer accessible. In return, the cyber-criminals behind it want you to pay them a lot of money that can vary from hundreds to thousands of dollars, usually in Bitcoin, Monero, or ZCash cryptocurrencies. They offer to get your files back and some of them even offer 1 free file for decryption so that you can see that they are not joking. We should also mention that ransomware extortion continues to evolve, with double and tripple extortion techniques.

Ransomware as a computer virus infection can be recognized by a custom file extension appended to each encrypted file, like “.encrypted” or so on. But some ransomware viruses may lock your device completely or even rename your files randomly, so that you cannot be able to recognize them at all. An example of a regularly updated ransomware threat that continues to release new iterations with different file extension is the so-called STOP/DJVU family.


The various types of computer “viruses” are designed to disrupt the normal functioning of a computer. These can spread via email, downloads, and even physical media such as thumb drives. To protect yourself from any type of computer virus, make sure your computer is up to date with the latest security patches, use a reliable anti-malware program, and be cautious when downloading files and opening emails from unknown sources.



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Ventsislav Krastev

Ventsislav is a cybersecurity expert at SensorsTechForum since 2015. He has been researching, covering, helping victims with the latest malware infections plus testing and reviewing software and the newest tech developments. Having graduated Marketing as well, Ventsislav also has passion for learning new shifts and innovations in cybersecurity that become game changers. After studying Value Chain Management, Network Administration and Computer Administration of System Applications, he found his true calling within the cybersecrurity industry and is a strong believer in the education of every user towards online safety and security.

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  1. richard

    nice article, thank you! can I quote you in my school paper?

  2. kurt

    In times like these, it feels extremely unfair that computer users are constantly bombarded with so many online threats! thank you for the educational read!


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