Saturday, March 06, 2004

Do computer viruses mutate? 

I recently got an email message from staff@berkeley.edu saying that people had complained about spam and virus-filled emails being sent from my address. I probably had a virus, the message said, and there were instructions for getting rid of it in the attached file. Turned out the attachment itself was a virus! I nearly fell for it; it was only the bad grammar and strange attachment name ("message.pif") that made me suspicious. The whole thing got me wondering: do computer viruses mutate the way real viruses do? According to Symantec, the answer is yes!
Each time a macro virus tries to spread, there is a chance it will inadvertently become corrupted or mutate; thus creating a new macro virus also capable of spreading. A large number of today's macro viruses exist because of this phenomenon.
What surprises me about this is that the overwhelming majority of file corruptions will result in a completely defunct virus, one which does nothing at all or simply crashes the host computer. Of course, one could make the same argument about genetic mutations in life. Okay. But although I can't prove it, I would guess that unlike computer code, the genetic code has evolved to be able to "withstand" mutations well. Changing a random allele in a genome will produce some biologically meaningful changes in the phenotype, while changing a random bit in a piece of computer code is likely to produce total junk. Even more unbelievable:
There are also many documented cases of two or more macro viruses mating with each other, combining in the same document to form wholly new macro virus strains, which share characteristics of both parent viruses.
UPDATE: Anyone know why so many viruses have such bad spelling and grammar? This article says it's because they're all created by people in Asia and Eastern Europe who don't speak English well, but I don't buy it. Another one wonders: "If the people who create these viruses are intelligent enough to program a virus that can infect millions, why is it they can't seem to form a coherent sentence?"
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