Since the earliest days of the Internet, people have tried to hack their way into the computers of others. Even as hacking has grown from a way for geeks to impress each other to a means for criminals to steal and blackmail, the strategy for computer security has remained largely the same: Companies and consumers erect the thickest walls they can around computers so the bad guys can't get in.

Now security experts, realizing they're losing the battle, are ready to try a new approach. They plan to recruit victims and other computer users to help them go on the offensive and hunt down the hackers. "It's time to stop building burglar alarms to keep people out and go after the bad guys," says Rowan Trollope, senior vice-president for consumer products at Symantec, the largest maker of antivirus software.