What was the first ever computer virus and what did it do?

Today, computer viruses and other forms of malware are one of the biggest threats we face online, costing users and businesses billions of dollars every year and the loss of countless files.

Malware comes in all shapes, sizes and classifications, including ransomware, key sniffers, adware, computer worms, Trojans and spyware.

And just like the computers and networks in which they thrive, malware too has a long and busy history of evolution. But where did it all begin?

While many may have pointed to the 1990s or even 1980s, the first generally recognised computer virus was actually authored back in 1971, long before desktop computers graced the majority of homes, and even pre-dating Microsoft, whose operating systems are now the most frequent target of malware.

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Written by Bob Thomas, it was called Creeper, so named after the villain of the Scooby Doo cartoon, and it was a simple piece of software that was designed to spread between computers, jumping from one to another, where it would display a message similar to “I am the creeper. Catch me if you can.” While the “virus” reportedly messed around with printers, beginning to print a file and then stopping, it wasn’t designed to be malicious, and was described as a mild annoyance as opposed to a genuine threat.

An enhanced version of Creeper was created soon after that would replicate itself as it spread, as opposed to simply jumping from one computer to another, but other than that, the enhanced version was largely identical to the original.

Of course, in 1971, the computer world was very much different to the one we know today. There was no Windows, Android or iOS. In fact, Creeper was designed to spread across DECSystem PDP-10 computers running the TENEX operating system. As you can determine from the image below, these computers are not ones you’d find in the average person’s living room.

Categorising what exactly Creeper was is perhaps more difficult when compared with malware that exists today. Despite the headline, from a purist’s point of view, Creeper wasn’t technically a computer virus. A computer virus is identified as such because it attaches itself to a host (i.e. a legitimate file or software) and spreads when a user unwittingly shares the infected host. Creeper, on the other hand, was able to move between computers by itself, meaning it would be more accurate to describe Creeper as a computer worm.

Even classifying Creeper as malware may be misnomer. Malware stands for malicious software, and Creeper wasn’t designed to be particularly malicious. Rather, it was designed to demonstrate the ability of software to jump or self-replicate between computers.

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Despite this, Creeper did spawn the first ever software that could be considered an antivirus of sorts. The software Reaper was soon designed to replicate and spread in the same way Creeper did, with the only function of that software to scan and delete any instances of Creeper it found on a computer.

In 1971, Creeper was not known as a virus, or a worm, or malware. Those terms simply didn’t exist at that point. Of course these days malware and viruses are very different, designed primarily with fighting a network or device’s security in mind. In 1971, it was a very different ballgame altogether.