In January this year, 20-year-old Jeanson James Ancheta pleaded guilty in a California court to charges that he had broken into government computers and taken control of them for purposes of fraud. He had planted Trojan software on the systems at the China Lake Naval Facility in California’s Mojave Desert, enabling him to manipulate computers on the network there. He had then used the computers to generate hits on Web site advertisements, for which the advertisers paid according to the traffic they received. The spyware or Trojan horses they plant on unsuspecting users’ machines do not draw attention to themselves, but once installed, they work as slaves to their remote masters. Bot networks, which are armies of these hijacked computers, have become the predominant feature of the Internet threat landscape.