Every time there’s a newsworthy virus attack, someone asks me where will it all end. The answer is in catastrophe. We are building a networked society on incredibly insecure foundations, and it is only a matter of time before someone figures out how to bring the entire system down. Actually, someone has already figured it out. Nicholas Weaver at Berkeley has written a fascinating paper on the possibility of what he calls a ‘Warhol worm’, so called because it could overwhelm the Internet in 15 minutes. The First Law of Technology applies here: if it can be done, it will.