The Most Dangerous Computer Viruses in History

The term "computer virus" dates back to the early 1980s. Since then, time and human intelligence have produced a large number of malicious programs that have shaped the history of computer software.

Below are some of the most damaging computer viruses ever unleashed on the internet. Today, robust antivirus software can shield your devices from these threats, but two decades ago the landscape was very different.

Melissa Virus (1999)

It is a computer virus developed by David L. Smith on 26 March 1999 that has infected more than one million users. It is named after an exotic dancer with whom David fell in love.

It was the first malware to be distributed by email in an attachment called LIST.DOC, which supposedly contained passwords for 80 adult (18+) paysites and was accompanied by the following message: "Here is the document you asked for. Do not show it to anyone else". After opening the file, the virus was automatically sent to the first 50 addresses in the Microsoft Outlook email address book.

Melissa did not delete or destroy files on the hard drive, but the sheer volume of automated emails overwhelmed mail servers worldwide. At the time, spam filters were virtually non-existent and Windows had no built-in defences, so corporate email systems buckled under the load.

The damage caused by Melissa amounts to over €100 million. David L. Smith was sentenced to 20 months imprisonment and a fine of € 5,000.

It later emerged that Smith received a relatively lenient sentence because he agreed to cooperate with the FBI and provide agents with the coordinates of the worm perpetrator, Anna Kournikova.

ILOVEYOU Worm (2000)

At the beginning of May 2000, the number of declarations of love was at least three times the statistical average. This is because someone came up with the idea of writing a nice computer virus that comes in the form of an "I LOVE YOU" email.

"I realised that a lot of people want love, so I named it that," explains the hacker.

The email contained an attachment with malicious code that automatically sent copies to all contacts in the victim's address book in Microsoft Outlook.
Within one day, the worm had infected 3 million computers. The attack overloaded corporate email systems and some IT managers shut down parts of the infrastructure to prevent further infections. The virus was even listed in the Guinness Book of Records as the most destructive virus in the world, causing €10 billion in damage.

Anna Kournikova Virus (2001)

It was developed on 11 February 2001 by a 20-year-old Dutch student, Jan de Wit. The name of this computer virus was not chosen by chance. In the title of the e-mail sent, the user was promised pictures of the then very famous Russian tennis player Anna Kournikova.

Many users did not hesitate to open the attached file AnnaKournikova.jpg.vbs without paying attention to the double extension and without having an anti-virus programme installed on their PC...

Eventually, more than 100,000 computers in Europe, North America and Australia were infected with this new virus, and although the economic damage was not very great, the "Anna Kournikova" virus became very popular. In particular, it was mentioned in an episode of the television series Friends in 2002.
On 14 February, Jan de Wit suddenly appeared at a Dutch police station to confess that he had caused the virus. As a result, he had to do 150 hours of community service.

CryptoLocker Ransomware (2014)

This is a new type of extremely dangerous virus that was spread by e-mail. As soon as the user opened the e-mail, an attached programme was automatically started that encrypted all files on the PC.

To regain control of the situation, the victim had to pay a large sum in Bitcoins in exchange for access to all the documents. After paying the money, the user received a private key that allowed them to access the files again. However, people were not aware that the files were lost forever after the infection.

Stay Protected with Antivirus Software

As we have already seen, there are many different types of computer viruses nowadays, and this list could go on and on. So be very careful when you surf the internet and open various unknown files and links.

The best way to protect ourselves from all security problems is to install an antivirus program on our PC, because nowadays it is very unsafe to surf the Internet without this protection. Antivirus protection saves you from malware, loss of money and time, violation of your privacy and other unpleasant surprises. You may also wonder whether PC antiviruses are still necessary — the answer is a resounding yes.

At Licendi, we stock a wide range of antivirus software at competitive prices. If you are unsure which programme suits you best, read our guide to the 4 best antivirus programmes for Windows.

If you have any questions, leave a comment or give us a call. We are happy to help.
Best regards,
Your Licendi Team