The World's Most Dangerous Viruses of All Time

1. CryptoLocker

Released in September 2013, CryptoLocker spread through email attachments and encrypted the user’s files so that they couldn’t access them.
The hackers then sent a decryption key in return for a sum of money, usually somewhere from a few hundred pounds up to a couple of grand.

2. ILOVEYOU

 ILOVEYOU is one of the most well-known and destructive viruses of all time.
The virus came in an email with a subject line that said “I love you”.
Being curious types, people clicked into the email with aplomb—regardless of the fact the email wasn’t from anyone they knew.
The malware was a worm that was downloaded by clicking on an attachment called ‘LOVE-LETTER-FOR-YOU.TXT.vbs’.

3. MyDoom

MyDoom, like ILOVEYOU, is a record-holder and was the fastest-spreading email-based worm ever.

4. Storm Worm

Storm Worm was a Trojan horse that infected computers, sometimes turning them into zombies or bots to continue the spread of the virus and to send a huge amount of spam mail.
Tip: never open a link in an email unless you know exactly what it is.

By July 2007, Storm Worm was picked up in more than 200 million emails.

5. Sasser & Netsky

Sasser spread through infected computers by scanning random IP addresses and instructing them to download the virus. Netsky was the more familiar email-based worm. Netsky was actually the more viral virus, and caused a huge amount of problems in 2004.

6. Anna Kournikova

Jan De Wit, a 20-year-old Dutch man, wrote the virus as ‘a joke’. The subject was “Here you have, ;0)” with an attached file called AnnaKournikova.jpg.vbs.

7. Slammer

The Bank of America’s ATM service crashed, 911 services went down, and flights had to be cancelled because of online errors. Slammer, quite aptly, caused a huge panic as it had effectively managed to crash the internet in 15 quick minutes.
15 minutes in and Slammer had infected half of the servers that essentially ran the internet.

8.Stuxnet

Stuxnet spread by a USB thumb drive and targeted software controlling a facility in Iran that held uranium. The virus was so effective it caused their centrifuges to self-destruct, setting Iran’s nuclear development back and costing a lot of money.