It was another four years, however, before self-replicating programs became "viruses." In 1983 and 1984 a graduate student at the University of Southern Califomia named Fred Cohen was experimenting with these programs and, at the suggestion of his adviser, decided to call them computer viruses. It was a catchier name, and also became the title of his 1985 doctoral thesis, in which he offered an explanation of viruses. A virus, he wrote, is "a program that can infect other programs by modifying them to include a slightly altered copy of itself." Further, "every program that gets infected can also act as a virus and thus the infection grows." Cohen also indicated that viruses presented a threat to computer security and could modify or damage data.
The thesis did not break any new ground in terms of computer science: in essence, Cohen took the known characteristics of selfreplicating programs and renamed them viruses. The term itself suggests that the programs are created in some kind of wild electronic biosphere and are capable of spreading incurable diseases from computer to computer--the high-tech equivalent of the biological viruses to which they are often compared. The sensationalistic use of the word would later prove to be fortuitous to computer security experts and have an irresistible appeal to rogue computer programmers. Though the word was perhaps chosen innocently, the metaphor was not entirely apt. Computer viruses, like biological viruses, are spread unknowingly, and they can mutate while spreading, but they are not created in the same way. Biological viruses are carried by small, natural organisms, over which man has little control; computer viruses, however, are simply programs--and computer programs are written by people.
Cohen's work quickly attracted attention, not least from a German computer system engineer named Ralf Burger. At the time, Burger was twenty-six and living in a small town near the Dutch-German border, not far from the city of Bremen. Burger became fascinated by the concept of viruses, and in July 1986 he had succeeded in creating his own, which he called Virdem. It was, to all intents and purposes, a simple self-replicating program, but with a small twist. For Burger, the "primary function of the virus is to preserve its ability to reproduce." After being loaded onto a computer, Virdem was programmed to hunt down and infect other files in the machine. When there were no more files to infect, the virus would begin "a randomly-controlled gradual destruction of all files."
In December 1986 Burger decided to attend the annual convention of the Chaos Computer Club in nearby Hamburg. The club had been founded in 1981 by Herwart Holland-Moritz--who prefers to be known as Wau Holland--and is a registered nonprofit organization. Holland, who was a thirty-two-year-old computer programmer at the time, set up the club as a hobby; despite the sinister implications of the name, it was chosen only because "there is a lot of chaos in the application of computers." According to the club's constitution, it is dedicated to freedom of information.
Since its foundation the club has proven itself adept at organizing media events, and this ability together with the connotations of its name have given the group a high profile. Like many clubs, Chaos unites people with a wide range of interests: there are members who see computers as a weapon for sociological change, others who simply want to play computer games, those who want to know how computer systems work, and those concerned with making a fast buck, legally or illegally. The Chaos members refer to themselves as data travelers, rather than hackers, but they all share the same obsession with computers and all vaguely subscribe to a vague notion of "hacker ethics." Their own unique understanding of that term is that they have a mission to test, or penetrate, the security of computer systems. Early Chaos Clubbers were allied with the VAXbusters, the group that sought to break through the security of VAX computers around the world. The club's first brush with notoriety, though, occurred in 1984, when they broke into Btx, or Bildschirmtext, an on-line text and information service patterned after Britain's Prestel. In 1986 they captured the media's attention again when, after the meltdown of the Soviet nuclear reactor in Chernobyl, they provided alternative information on contamination levels by hacking into government computers and releasing the data that they found. Their findings were sufficiently at odds with official reassurances to make them the darlings of Germany's Green movement.
