Digital pathogens spread so quickly, however, that even the most diligent patchers could be at risk. At a security symposium last August, Mr. Staniford and two co-authors presented "How to Own the Internet in Your Spare Time," which described a computer simulation of a worm attack. The worm in the simulation attacked machines that had been selected earlier as ripe targets, instead of randomly probing the Internet. The simulation found that within 15 minutes, the worm would have infected more than nine million machines. Mr. Staniford called it the Warhol worm, a nod to Andy Warhol's famous line about fame.

Virus outbreaks spurred by contaminated e-mail now occur more frequently, spreading digital pathogens that add trauma to the lives of harried tech-support staffs.

Still reeling from ILOVEYOU's brutal kiss, technophiles were panicked last week by news of yet another digital pathogen. This virus, first reported by a pair of European security firms, was rumored to burrow its way deep into Spanish cellphones, an innovative twist that had computer pundits branding wireless cyberattacks the next big thing.