Computer viruses began as a theory by John von Neumann
Long before anyone wrote a virus, the mathematician John von Neumann showed in theory that a program could copy itself. Fred Cohen later confirmed it experimentally and wrote a 1987 doctoral dissertation on computer viruses. Today the malicious descendants of that idea number in the hundreds of millions, with more than 669 million variants counted in 2017 alone.
Malware, short for malicious software, covers any program built to disrupt systems, steal data, grab unauthorised access or lock people out of their own information. The family includes viruses, worms, Trojan horses, ransomware, spyware and keyloggers. That 2017 tally of 669,947,865 variants, from Symantec, was double the previous year's, and cybercrime was forecast to cost the world 6 trillion dollars in 2021.
Before the internet was widespread, viruses travelled on floppy disks, hiding in programs or boot sectors so they ran whenever the software launched or the disk started up. The earliest targeted the Apple II and Mac, but they flourished once MS-DOS machines dominated. Brain, a boot-sector infector and the earliest known to spread among IBM PCs in the wild, was written in 1986 by the Farooq Alvi brothers in Pakistan. In the 1990s, flexible macros in Microsoft Word made it possible to hide infections inside ordinary documents.
Worms, which spread across networks on their own, began on multi-user Unix machines rather than PCs. The 1988 Morris worm, the first well-known example, hit SunOS and VAX BSD systems by exploiting holes in server programs rather than attaching itself to files, a technique worms still use. Like many early infections, it started as an experiment.
Broadband changed the motive to money. Since 2003 most widespread viruses and worms have aimed to hijack computers, turning them into 'zombies' that send spam or launch denial-of-service attacks for extortion. Email became the main delivery route, carrying 96 percent of malware according to a 2018 Verizon report, and even USB lights, fans or toys can carry infections picked up during manufacturing. Since 2021 some malware has targeted critical infrastructure such as electricity grids.
Source: Malware
