In the early days of personal computers, computer viruses have come a long way. 25 years ago, viruses are developed just for bragging rights (especially with teens). Creating malware designed for fun and mischief.

Now, viruses are becoming sophisticated and hackers have gone professional, and their evil ambitions have grown. Instead of working out of their parents’ basement back in the good ol’ days. Virus creators are sometimes part of an underworld criminal, or working directly for an intelligence agency for espionage.

So here are the top 5 list of the most destructive computer viruses in the history.

1.) Poison Ivy

Damage cost: Estimated $20,000,000

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It is a cyber-security’s worst enemy; it allows the hacker to secretly control the infected computer. It is a type of Malware and is also known as a “remote access Trojan,” because it provides full control to the perpetrator through a backdoor.

When the virus is installed, the hacker can take control of the infected computer to record or manipulate its content or even use the computer’s webcam to record audio and video.

It was once considered a tool for amateur hackers. Poison Ivy has been used in sophisticated attacks against dozens of Western firms, including those involved in defense and chemical industries, according to a white paper written by Symantec, the computer security firm. The attacks were traced back to China.

2.) My Doom

Damage cost: Estimated $40,000,000

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This virus snuck its way into the world of malware in 2004. Swiftly infecting millions of computers and launching a massive distributed denial of service attack, which overwhelms a target by flooding it with information from multiple systems and causing massive havoc in its path.

The contagion is spread via email as what seems to be a bounced message. When the victim opened the infected email, the malicious code will automatically download and then pilfered the new victim’s Outlook address book. From that address book, it will spread like a fire to the victim’s friends, family and colleagues and anyone in the contacts. MyDoom’s spread faster than any worm seen prior. It is a very damaging malware especially to Microsoft Windows based computer. The US government offered a $250,000 bounty to those who can give a lead to catch the virus creator.

3.) Fizzer

Damage cost: $20,000,000

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In between 2003-2004, worms and malware were spreading over e-mail, but Fizzer was an entirely new species.

Fizzer was purely all about money and this makes this virus very scary. While some underestimated the seriousness of the worm because it wasn’t as fast spreader as MyCode or PoisonIvy, Fizzer was more insidious.

What makes Fizzer stand out is that it’s the first instance of a worm created for financial gain. “Computers infected with Fizzer started sending out pharmacy spam.” In other words, Fizzer didn’t just take over your email contacts for the sake of spreading, it used your address book to send out the porn links and pills spam (Sounds familiar!). Microsoft even offered a $250,000 bounty for information leading to the arrest of its creator.

4.) Code Red

Damage cost: Estimated $125,000,000

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Compared to the previous viruses, Code Red looks like an almost a more gentle and more kind version of a threat. But when it spreads across computers worldwide in 2001, it caught security experts off guard by taking advantage of a flaw in Microsoft Internet Information Server. This server manages most of the web hosting at that time. Hence, it is very destructive and earned its name in the list

It took down almost all the websites. Yikes! Perhaps most memorably, Code Red successfully brought down the website and forced other government agencies to temporarily take down their own public websites as well.

5.) I love you <3

Damage cost: $6.7 Billion!

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Back in 2000’s, millions of people around the world made the mistake of opening an innocent looking email attachment labeled simply, “I Love You.”

Three sweet words that lead billions fall into trap. Instead of revealing a confession of a secret admirer, as perhaps readers had hoped, the file released a malicious program that overwrote the users’ image files. Then like an old-fashioned chain letter gone nuclear, the virus e-mailed itself to the first 50 contacts in the user’s Windows address book.

While by today’s standards, Love Letter is almost quaint, it did cause wide-scale problems for computer users. It is worse than Corona, It only took hours for Love Letter to become a global pandemic!

This is because it played on fundamental human feelings: the desire to be loved. In that sense, an innocent looking Love Letter could be considered the first socially engineered computer virus.

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