The idea of a computer virus was first theorised by the mathematician John von Neumann in 1949, when he envisioned the possibility that a “mechanical organism”, such as a program, could reproduce itself and infect multiple hosts.

The title of the first computer virus in history is attributed to a program called Creeper, created by Bob Thomas from BBN Technologies in 1971. Founded in 1948, BBN Technologies was an American high-technology and research company that played an essential role in building the earliest internet networks, including ARPANET and the Internet. While working for BBN, Bob Thomas developed the Creeper program out of scientific curiosity, to test whether it was possible to create a self-replicating program that could move between computers.

Written in PDP-10 assembly, the Creeper program ran on the TENEX operating system, which was developed by BBN in 1969. The Creeper used ARPANET, the predecessor of the Internet as we know it today, to infect other computers that used the TENEX operating system. Once infected by Creeper, the affected computer would display a message saying “I'M THE CREEPER. CATCH ME IF YOU CAN!”, and would start printing a file, only to then stop this action, and jump to another computer on the network. By doing this, the Creeper would effectively remove itself from the computer it had previously infected.

The Creeper program developed by Bob Thomas did not have the ability to self-replicate, and therefore to multiply itself and spread, but rather it jumped from a computer to the next. For this reason, there are debates on whether it is correct to define it as the first virus in history, considering that it does not fully conform to the technical definition of a virus. However, the notion of computer virus did not exist at the time, and was only developed by Fredrick Cohen 12 years later, in 1983. Regardless, the Creeper program played a fundamental role in confirming the theories of von Neumann, proving that it was possible to create a program with the ability of transmitting itself automatically.

Following the creation of Creeper, Ray Tomlinson, one of Bob Thomas’ colleagues and the inventor of email, developed an enhanced version of the program that had the ability to self-replicate and therefore leave a copy of itself on infected computers, rather than jumping from one computer to the next. As a counteractive measure to the enhanced version of Creeper, the first antivirus program in history, called Reaper, was created, which successfully moved through the network to find copies of Creeper and eliminate them.

Unlike the viruses we know today, the Creeper did not have a malicious intent and did not engage in any activity that could damage the computer, and steal or damage data. The only action it performed was displaying the message mentioned above, and its only purpose was to demonstrate a mobile application. The Creeper, therefore, caused only a minor inconvenience to the users of the infected machines.

It is important to note that both the Creeper and the Reaper were self-contained programs and did not leave the BBN network experimental setting. The first virus found in a non-experimental setting was called Elk Cloner. Developed in 1982 by the 15 years old Richard Skrenta, Elk Cloner affected Apple II computers via infected floppy disks. Once the infected floppy disk, usually containing a game, was inserted in a computer, Elk Cloner would spread both to the computer and to any other floppy disks present in the machine. As with the Creeper, Elk Cloner did not have a malicious intent and did not cause any damage. Created as a practical joke, it would only cause annoyance, by displaying a short poem when the game in the infected floppy disk was booted for the 50th time. The first virus affecting Windows based PCs was recorded in 1986 and was called Brain. It was developed by two brothers, Basit and Amjad Farooq Alvi, as a means to protect their medical software and prevent it from being pirated. Similarly to the two viruses mentioned above, Brain did not intend to cause any harm, and in its code it even included the address and phone number of the two brothers, so that they could be contacted by the users of infected machines to remove the virus.

It is possible to see that at their inception computer viruses were created to achieve fame and recognition, to perform practical jokes, or for curiosity, to test the boundaries of the new technology available, and did not intend to cause any damage. These viruses would usually alert the users of the infected computers and inform them of the presence of a virus with enigmatic messages, poems and animation. The shift to the destructive viruses we know today, started occurring at the end of the 1980s when individuals started experimenting with malicious code, and later realised that viruses could be used to steal personal data, hijack computers, and could lead to financial gain. This led to the first destructive viruses, such as Michelangelo in 1991, which would wipe the hard drive of infected machines on March 6th. In addition, with the advent of email, viruses could now reach a large number of computers in a short period of time, therefore simplifying the mode of transmission, such as the Melissa virus in 1999, which spread via email and caused over $80 million in damages.

Starting from the early 1990s, computer viruses were no longer the product of young individuals engaging in practical jokes or looking for recognition, but rather, they started being developed by highly skilled individuals, professional hacker groups and criminal organisations. Following the exponential increase in the number of viruses created, the antivirus software industry, initially born as a program to counteract Creeper, is now worth billions of dollars.

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