The PC virus celebrates its 20th year of existence following the detection back in January '86 of the boot sector virus, Brain, which infected computers via floppy disk. While the virus Brain itself was relatively harmless, it set in motion a long chain of events leading up to today's virus situation.
Boot sector viruses, now long extinct along with the floppy disk, held a relatively long reign from 1986 to 1995. Since transmission was via disk from computer to computer, infection would only reach a significant level months or even years after its release. This changed in 1995 with the development of macro viruses, which exploited vulnerabilities in the early Windows operating systems. For four years, macro viruses reigned over the IT world and propagation times shrank to around a month from the moment when the virus was found to when it was a global problem.
As email became more widespread, so followed email worms and individual worms which reached global epidemic levels in just one day. Most notable in this connection was one of the very first emails worms, Loveletter aka ILOVEYOU, which caused widespread havoc and financial loss in 1999 before it was brought under control.
In 2001, the transmission time window shrank from one day to one hour with the introduction of network worms (such as Blaster and Sasser), which automatically and indiscriminately infected every online computer without adequate protection. Email and network worms still today continue to cause havoc in the IT world.
At present there are over 150,000 viruses and the number continues to grow rapidly. The biggest change over these 20 years has not been in the types of viruses or amount of malware: rather it has been in the motives of the virus writers.
"Certainly the most significant change has been the evolution of virus writing hobbyists into criminally operated gangs bent on financial gain," says F-Secure's Chief Research Officer Mikko Hyppönen. "And this trend is showing no signs of stopping."
Hyppönen continues: "There already are indications that malware authors will target laptop WLANs as the next vector for automatic spreading worms. Whatever the next step might be, it will be interesting to see what kind of viruses we will be talking about in another twenty years time – computer viruses infecting houses, perhaps?"