Hot news from Southwark Court! Aaron Caffrey, the nineteen-year-old whose computer launched a denial of service attack that crippled the Port of Houston, has been found not guilty. His defence -- that someone else hacked into his computer, took it over and used it for the attack -- clearly raised enough doubt in the minds of the jury to get him off the hook. Tons of expert witness testimony that there was no evidence of this having happened couldn't counter the proposition that it might have done. Expert jurors might have had a different view of the balance of probabilities, but you get to be tried by your peers in this country. And a good thing too.
This is going to make it very hard to prosecute hackers in the future, as the key evidence will always be on a computer and computers will always be open to this sort of doubt -- at least, until the vision of secure systems that only run signed code comes about.
On the other hand, if some canny black hat has already secreted something untoward on your PC, how could you tell? Antivirus software can only scan for things that have caused trouble or otherwise called attention to themselves; even the heuristic stuff that looks for bad behaviour rather than known bad code can't do much until the infection kicks off. A stealth virus that quietly and slowly creeps around the place, keeping its head down until triggered, is almost certain to occur at some point. It might be here already: could we tell?
Me, I'm turning off my computer and fleeing the country for the weekend. Whatever happens, it wasn't me.