What Are The Top Computer Viruses?

The history of computer viruses started in 1983 when the first of them was written. An American student did this and after this, many other similar programs begin to appear one after another. Most of the computer bugs are quite small, but some of them have caused great damage to both ordinary people and large corporations, and even countries.

As for the anti-virus programs, they were launched only in 1988. Since that time, this sphere has also developed a lot, and these days, company cyber security issues are of great importance. We must remember both dangers and their prevention. So, let’s discuss both questions.

The most famous computer viruses

Of course, there are more than 10 types of computer viruses. However, the top 10 are well-known for the damage they caused.

My Doom

This PC virus appeared in 2004 and was more than destructive. It brought damage of more than $38 billion. In addition, there were some lasting unpleasant consequences of its attack.

The virus provided attackers with access to the computers and installed programs. Emails were affected by it.


This virus was contained within an email attachment. When the latter was opened, a copy was sent to the contacts automatically. It also made some malicious system changes. It occurs in the following manner:

  • The letter was sent in 2000 from the Philippines.
  • ILoveYou was the subject, and the script was attached.
  • Because the virus extension was hidden, most users did not expect anything to go wrong.

It infected over 3 million computers worldwide in total. The estimated cost of the damage was $10-15 billion.

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Among different computer viruses, this one is a 500-kilobyte tool that has once infected the software of at least 14 industrial enterprises in Iran, including a uranium enrichment plant.


In 2003, this virus caused damage to more than $37 billion. It spread fast via email:

  • After opening the letter, it penetrated the computer.
  • It copied files, sent emails, and damaged both software and hardware.


This one caused a lot of problems in 2004, resulting in $500 million in damage. Moreover, the mapping system of the British Coast Guard was destroyed by it. A teenager from Germany created this harmful program.


Cryptolocker is a ransomware virus that was released around the beginning of September 2013, targeting all versions of Windows. This was a new, extremely dangerous type of computer virus.

Like other beggar viruses, CryptoLocker locks, in this case, encrypts, information on the hard drive and asks you to pay money to gain access to it again. New for such viruses was the addition of a time limit on ransom – users have three days to pay $ 300, € 300, or 2 bitcoins before the encryption key is destroyed forever and the information is lost. To feel the inevitability of retribution, a timer is displayed, counting down the time until the key is destroyed.


WannaCry is a ransomware virus that became widespread in 2017. It is a modified version of the US National Security Agency’s Eternal Blue malware.

Code Red

The virus was launched in 2001 and infected 360,000 computers, creating a botnet to attack the White House website. After the attack, a message appeared on the screen with words ‘Hacked By Chinese!’.

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ZeuS (or ZBot) was a new type of Trojan that appeared in 2007 and is designed to attack servers and intercept data.

The Trojan was intended for all versions of Windows, and due to its structure, which allows it to work without connecting the program to drivers, it can infect a computer even from a guest account.

After entering the system, the program intercepts the user’s registration data and is able to transfer funds to the accounts of other victims in small amounts, which makes it impossible to search for and track the resource of hackers.


Slammer, which appeared in 2003, affected mainly the automated systems of banking institutions, causing an estimated $750 million in losses. In total, more than 200 thousand computers around the world succumbed to the action of this virus. It also caused a noticeable slowdown in the Internet connection.

Virus vs Worm

Sometimes we call them computer bugs, sometimes viruses and worms. Actually, there is a difference between the last two options, namely:

  • A virus is a program that can enter a computer in a variety of ways and cause effects ranging from just annoying to very destructive.
  • A worm is a program that is very similar to a virus. It is capable of self-replication and can lead to negative consequences for the system.

The main difference between them is that worms are able to reproduce on their own. They do not depend on files on the computer or boot sectors. Worms are sent using email addresses from the victim’s contact list or exploit vulnerabilities in various applications for this.

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Due to the wide availability of the Internet, worms often spread rapidly around the world within hours or even minutes of their appearance. This ability makes them more dangerous than other types of cyber threats.

How do you know if your computer has a virus?

Slow performance, application crashes, and freezing can sometimes be a sign that a virus or other type of malware is interfering with your computer. However, many other issues can slow down your PC.

Some applications pop up a command prompt window when they update, so strange windows flashing on your screen and quickly disappearing may be a normal piece of software and not a sign of malware. Similarly, just because your computer is working fine, it doesn’t mean that the device is free of malware.

Modern viruses most often hide in the background so that they cannot be detected, and they can easily steal your personal information, such as passwords, credit card details, etc. In other words, malware today is often created simply to make money, and some masterfully designed viruses won’t cause any noticeable problems with the PC at all.

Sometimes malware causes problems with the PC, and sometimes it behaves well. However, a sudden slow PC performance may be one of the signs that you have a virus on your computer. The only way to know for sure if a device has malware is to completely scan your system and then clean computer of viruses.