What Are The Top Computer Viruses?

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

computer virus

The antivirus programs were only brought to the market in 1988. Since that time, this area has also developed a lot, and nowadays Corporate cyber security Topics are of great importance. We need to be aware of both the dangers and how to prevent them. So let’s discuss both questions.

The most well-known computer viruses

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

my downfall

This PC virus appeared in 2004 and was more than destructive. It caused more than $38 billion in damage. In addition, there were some lingering nasty aftermath of his attack.

The virus gave attackers access to the computers and installed programs. Emails were affected.


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

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

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


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

that big

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

  • After the letter was opened, it penetrated the computer.
  • It copied files, sent emails, and corrupted both software and hardware.


This caused many problems in 2004, resulting in $500 million in damage. It also destroyed the UK Coastguard’s mapping system. A teenager from Germany created this malicious program.


Cryptolocker is a ransomware virus released in early September 2013 that targets all versions of Windows. This was a new, extremely dangerous type of computer virus.

In this case, like other beggar viruses, CryptoLocker encrypts information on the disk and asks you to pay money to access it again. What was new for such viruses was the addition of a ransom time limit – 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 vengeance, a timer will appear, counting down the time until the key is destroyed.

I could cry

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.

Red alert

Introduced in 2001, the virus infected 360,000 computers, creating a botnet to attack the White House website. After the attack, a message appeared on the screen saying “Hacked by the Chinese!”.


ZeuS (or ZBot) was a new type of trojan that appeared in 2007 and was 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 with drivers without connecting the program, it can infect a computer even from a guest account.

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


Slammer, which appeared in 2003, primarily affected the automated systems of banking institutions and caused an estimated $750 million in losses. In total, more than 200,000 computers around the world succumbed to the effects of this virus. It also caused noticeable internet connection slowdown.

Virus vs Worm

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

  • A virus is a program that can get into a computer in a number of ways and cause effects that can range from simply annoying to very destructive.
  • A worm is a program 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 capable of reproducing themselves. 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 by exploiting vulnerabilities in various applications.

Due to the wide availability of the Internet, worms often spread quickly 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 freezes can sometimes be a sign that a virus or other type of malware is interfering with your computer. However, many other problems can slow down your PC.

Some applications will pop up a command prompt window when updating, so strange windows blinking on your screen and quickly disappearing may be normal software and not a sign of malware. Likewise, just because your computer is working well doesn’t mean the device is malware-free.

Modern viruses mostly hide in the background so they cannot be detected, and they can easily steal your personal information like passwords, credit card details, etc. In other words, malware today is often created just to make money, and some more Masterfully engineered viruses don’t cause any significant problems with the PC at all.

Sometimes malware causes problems with the PC, and sometimes it behaves well. However, a sudden slowdown in PC performance can be one of the signs that you have a virus in your computer. The only way to know for sure if a device contains malware is to do a full scan of your system and then clean the computer of viruses.