Computer viruses have caused millions of dollars in damage to businesses around the world. While some are annoying but relatively harmless, others are developed by professional hackers.
Approximately 30% of all computers in the United States have been affected by malicious software. Cybercriminals will often corrupt your files, steal your private information, or hold your computer hostage until you pay for the virus removal.
Here are 5 of the worst viruses in history:
Melissa was created by David L. Smith, who named it after a stripper based in Miami. The virus infected Windows computers, and rather ironically, it wasn’t created to cause harm.
Unluckily for Smith, the virus was so successful that it completely overloaded servers, emailing a user’s first 50 email addresses with the passwords to 80 different pornographic websites.
Melissa is notable as it was one of the first viruses to be email-activated. It shut down safeguards within the PC, lowered security settings, and disabled macro security. Thousands of people were unable to access their emails and it caused approximately $1.2 billion in damage and losses.
Smith was prosecuted and served 20 months in prison. He was also banned from using a computer without court consent.
This virus was first seen in 2004 and mostly affected Windows OS. Unlike most viruses, it didn’t spread through email. Instead, it would infect a computer and then look for vulnerable systems, instructing those systems to download the virus. The operating system was altered so that it was difficult to reset without completely cutting the power.
Sasser was developed by Sven Jaschan, who released it on his 18th birthday, allowing it to run wild and infect a number of organizations- including Goldman Sachs.
ILOVEYOU was arguably the most dangerous worm ever created. It was able to replicate itself and after users opened the subject line (which said it was a love letter), it would email itself to 50 of the contacts available in the user’s address book.
ILOVEYOU managed to get deep into computers, copying itself and hiding in folders, replacing files, and adding new files. One of the things that made this virus so dangerous was the fact that it was also stealing passwords and emailing the information to hackers.
ILOVEYOU did approximately $10 billion of damage while infecting computers around the world.
4. My Doom
My doom was first seen in January 2004 and traveled via email- targeting random addresses. The virus worked by activating a denial of service attack and was originally spread through file-sharing application KaZaA before spreading to emails.
The email was particularly malicious as computer users would see the subject line “Mail Transaction Failed”. This caused the virus to spread like lightning, and almost two million computers were infected, causing $38 billion of damage and infecting 1 in 12 emails.
Leap-A has flown under the radar, but one of the reasons why it’s so notable is it was the first proof that Apple computers can be hacked.
In 2006, Leap_A virus was spread through the Apple iChat instant messenger. Infected computers would pass it on by sending each person on the user’s iChat list a corrupted file appearing to be a JPEG image.
While the virus didn’t cause as much damage as some of the others, it sent shockwaves around the world. Apple users who were previously smug about their virus protection realized they could be hacked after all.