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10 Most Dangerous Types Of Computer Viruses

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By: Shimon Brathwaite

August 9, 2021

Computer viruses are by far the most popular type of malware within cybersecurity. Simply put, a computer virus is a type of malware that spreads by infecting a legitimate computer program. Almost everyone has had a computer virus at some point in time, and it’s well known that it can do a lot of damage to your computer. However, not all computer viruses are the same in terms of the damage that they can do. Some viruses only display ads or cause mild performance issues, while other viruses steal passwords, corrupt data, or make a machine completely unusable. Viruses differ in the damage they cause and their built-in mechanisms for avoiding detection and other distinct characteristics. The potential damage depends on the type of virus, and, in this article, we will discuss the ten most dangerous types of computer viruses:


This is probably the most dangerous and profitable computer virus in existence. Ransomware gets its name because it encrypts all of the data on the victim machine and demands payment to decrypt the data. Since most people and companies can’t function without their data for long, most people end up paying the ransom. Since this type of virus extorts victims directly for money, it’s one of the worst types of computer viruses to get infected by.


A keylogger is a computer virus that records the keystrokes of the machine that it has infected. This is a security risk because when you type a password, email, social security number, credit card information, and any other confidential information, it gets recorded and sent to the owner of the keylogger.

Polymorphic virus

Polymorphism means the virus can change its code without the need for the malware author to make any changes. Polymorphic viruses can evade detection by many antivirus solutions by changing the way their code is structured. This avoidance is possible because many antivirus programs use signature detection, which checks for programs matching the established signature of a virus to determine whether it is malicious or not. If a virus can change its code, it can change its signature and avoid detection. This makes a polymorphic virus especially dangerous.


These viruses are very effective because they attach themselves to legitimate Microsoft files, convincing people to download them from emails and open them. In Microsoft files such as Word or Excel, one can create code scripts called “macros.” Malicious scripts are attached to the Microsoft files and then executed once opened, enabling the macros. Since these files are commonly used in business and personal life, creating a macro and sending it via a phishing email is an effective way to get people to run that virus.

Browser Hijacker

This type of virus targets web browsers, altering the browser settings and redirecting to malicious websites. For example, this virus may redirect to a replica of a popular banking website so that login information gets sent to the virus’s author. Or it may just redirect visitors to websites to generate traffic or ad revenue. This type of virus can be very convincing if the website redirects are very similar to the original website.


This type of virus has grown significantly in profitability with the steady increase in the cryptocurrency’s value. A crypto miner is a type of virus that uses the processing power to mine cryptocurrencies, such as Bitcoin. Bitcoin and most other cryptocurrencies have grown in value, making crypto miners viruses that much more valuable to their creators.


A rootkit is a computer virus designed to access a computer portion that should not otherwise allow access. This type of virus is so difficult to remove that it can infect portions of the computer outside of the operating system, such as the section responsible for booting up the computer. Doing this circumvents safeguards like antivirus and other operating system defenses and makes rootkits extremely difficult to remove.

Bot malware

A bot is simply a controlled computer, and a botnet is a group of controlled computers used to perform a certain action. This type of computer virus sits on a computer and awaits instructions from a Command & Control server. Once this virus receives these instructions, it uses each computer to perform an attack on another device.


This type of virus is all about gathering information about the user without them knowing. One can see an example of spyware in any movie that a hacker was watching someone through their camera. Unlike other types of viruses, spyware focuses on staying undetected on a machine for as long as possible, making it one of the most intrusive types of computer viruses.


Whenever a virus exploits a vulnerability, one of two things could be happening. One is that the virus is programmed to exploit a known vulnerability with an existing fix that did not apply. The second and more difficult option is that it is zero-day, which is a virus that exploits either a previously unknown vulnerability or a vulnerability that doesn’t have a fix. The issue here is that there isn’t even a fix for the vulnerability that the virus exploits, and there probably isn’t a signature to detect it, so preventing a zero-day virus can be very difficult.


Computer viruses are pieces of malicious code that spread by infecting other files. They can be differentiated by how they spread, what damage they do to a computer or any other distinguishing characteristics. Computer viruses can do significant damage to a machine and the owner of the machine by providing the attacker access to that person’s accounts and information. However, some viruses may stay undetected for a long period, collecting information or recording user behavior. The best way to detect hidden computer viruses is by scanning them, using antivirus or antimalware solutions.

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