Computer viruses can wreak havoc on the systems of millions of people from around the world, and they can affect both Macs and PCs. Without properly safeguarding your computer with the right antivirus software, firewall, and recovery software from companies like, all of your files can be left vulnerable to attacks from viruses, hackers, and all types of malware.

But even though there are countless viruses out there, which ones have been the biggest of all time? Continue reading to learn about a few of the worst viruses to ever be released.

Storm Worm

Storm Worm was identified in the latter part of 2006, when it was recognised as being carried via email to its victims. The subject of the email was “230 dead as storm batters Europe,” so that’s how it got its name, even though different antivirus companies call it by various names.

This Trojan horse virus could either turn your computer into a bot or a zombie, so if your computer became infected, it would be vulnerable to control from remote, and it could be used to set up a botnet to send spam all over the Internet.


The MyDoom virus struck in 2004 and it infected more than 2 million computers. It, too, was spread via email, appearing as a bounced message. When the email was opened, malicious code downloaded automatically onto the system of the victim. Once downloaded, it was able to go through the address book in Microsoft’s Outlook. From there, it could then send itself out to everyone within the address book, from friends and family to work colleagues. This is how it became the fastest-spreading worm up to that point in time.


SOBIG.IF also infected more than 2 million computers back in 2003. This Trojan worm was able to disguise and replicate itself so that it wouldn’t appear as malware and it wasn’t easy to detect. It was spread via email and infected a person’s computer after they opened the message. Once in the system, it went after the address book, just like MyDoom. But what made this virus different was the fact that it sent out so many emails at once that it could easily inundate anyone’s computer. In addition to affecting personal computers, SOBIG.IF was able to stop computer traffic in Washington, D.C., as well as ground Air Canada and slow down the computers at several major businesses.

Code Red

The Code Red virus of 2001 infected a million computers. This is yet another worm that rapidly spread through computers that ran Windows NT and Windows 2000 at the time. It would randomly select IP addresses, scan them, and infect computers using these operating systems in order to take down websites.

As you know, there are so many computer viruses that strike victims every day, from the largest corporations to individuals working on their home computers. To safeguard against these viruses, always have your firewall turned on and a reputable antivirus and anti-malware program installed. More importantly, keep your computer and these pieces of software updated so they can effectively guard your system against attacks.