Deadliest Computer Viruses in History

A computer virus is a type of malicious software, or malware, that spreads between computers and causes damage to data and software.

10.- ILOVEYOU 💓

ILOVEYOU, sometimes referred to as Love Bug or Love Letter for you, is a computer worm that infected over ten million Windows personal computers on and after 5 May 2000. It started spreading as an email message with the subject line "ILOVEYOU" and the attachment "LOVE-LETTER-FOR-YOU.TXT.vbs."

9.- Code Red

Code Red was a computer worm observed on the Internet on July 15, 2001. It attacked computers running Microsoft's IIS web server, the largest group of infected computers was seen on July 19, 2001. On that day, the number of infected hosts reached 359,000 .

8.- Melissa 

This virus started in 1999 as an infected word document. This was posted online, claiming to be a list of passwords to adult websites. Once opened, it would mail itself to the user's email contacts. The increased email traffic caused disruption to governments and corporations alike.

7.- Storm Trojan

In 2007, Storm Trojan infected thousands of computers. Users activated it by opening emails with titles such as "230 dead as storm batters Europe". Then, a program called wincom32 would install itself. This passed information to other infected computers. These computers would then spread the virus.

6.- Sasser

Sasser affected millions of Windows XP and 2000 computers. It found a way to manipulate an exploit in the Local Security Authority Subsystem Services. Sasser slowed machines down and caused crashes. It also made it hard to power down. Damages were estimated in billions of dollars as well as forcing airlines and governments to shut down.

5.- My Doom

One of the fastest spreading virus of all time, My Doom, infected one in 12 emails at its peak. Users would open an attachment like "Mail Transaction Failed". Its aim was to take down websites like Google and Lycos. It managed to take out Google for almost a day!

4.-Conficker

Conficker is a worm that infected over 9 million computers around the world. It would reset account lockout settings and block access to antivirus sites and windows updates. It would then lock out user accounts. Scareware was then used to scam money from users.

3.- Zeus

In 2009, Zeus targeted windows computers to use them to perform criminal acts. It infected targets through phishing scams or downloads. It compromised accounts from many leading banks and corporations. It stole details of social media accounts, bank accounts, and email addresses. Around $70 million was stolen and over 100 arrests made.

2.- Stuxnet

Believed to be created by Israeli and American defense forces for cyber warfare, Stuxnet was used to disrupt Iran's nuclear program. Spread through infected USB drives, it ruined 1/5 of Iran's nuclear centrifuges. If the infected computer used Siemens software, it would alter the speed of the machinery it controlled, causing it to tear apart.

1.-  CryptoLocker

Cryptolocker was one of the first ransomware attacks. This virus encrypted files on hard drives. The only way to remove the encryption was to pay a ransom by a certain deadline. Law enforcement managed to stop the ransom operation, but not before $27 million was paid.