The World's Worst Computer Viruses and Worms

Say what you want about humanity, we’re certainly an enterprising bunch. As soon as we invented the computer, some of us began creating ways to screw it up with the many forms of computer viruses. Fortunately, we also have a few specimens of the opposite mindset, and before long, an entire antivirus software sub-industry grew up, the sole purpose of which is to vaccinate computers against computer viruses and destroy them when possible. Both sides of this spectrum have matured a lot in the last four decades, and with that in mind, here’s a look at a few of history’s most memorable computer viruses.

1. Creeper – While computer scientists were working on The Advanced Research Projects Agency Network, an early ancestor to the internet known as ARPANET, the program known as Creeper was invented. Apparently harmless, Creeper was simply programmed to look for computers attached to the network, transfer itself to them and flash the message, “I’m the creeper, catch me if you can!” It would then look for another computer and repeat the process. Those in the know say that Creeper is also significant because it shows that the roots of computer viruses are tightly intertwined with the origins of the internet.
2. Jerusalem – Touted as the first computer virus with destructive capabilities, Jerusalem simply deleted all software on machines it infected. This computer virus is the granddaddy of every subsequent form of malware. This virus was first discovered in 1987 at Hebrew University.
3. Melissa – The product of a person with too much time on his hands and named for an, ... uh ... exotic dancer, Melissa is significant because it was essentially the first computer virus that was designed to make money. Specifically, while Melissa itself was simply known for mailing itself to computer users and paralyzing their email systems, it also inspired a copycat version. The copycat version found files on infected machines and then held them hostage, stipulating that it would decrypt said files once the user transferred $100 to an offshore account. Yes, Melissa was pretty sneaky.
4. I Love You – Are you extremely careful when you check your email? Do you make sure to never open emails from people you don’t know? Do you avoid opening attachments to sketchy emails? If you do, and you definitely should, odds are good that a lot of that caution stems from our collective experience with the I Love You worm. Eventually costing infected companies upward of five billion dollars, this computer virus came as an attachment to an email message with a subject line that read, “I love you.” When people opened the attachment, the virus infected their computers and then sent the same email to everyone on their contact list. That’s some tainted love right there.
5. Stuxnet – Stuxnet is something like the cyber-shot heard ‘round the world. Stuxnet is considered the first of its kind in a new type of online warfare. Used against a nuclear plant in Iran and said to be so complex that only a government lab could develop it, Stuxnet is a computer virus that burrows into an internal network until it finds its target. It then destroys the system. Powerful Stuxnet is pretty scary stuff.

From mischievous fun and games to outright hostility ranging from ransom-ware to government sabotage, viruses are always evolving. While most antivirus software on the market is capable of dealing with the majority of threats, it pays to be cautious.

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