Nobody knows for sure why Asia and Latin America were so hard hit, but Huger and Porras both said countries with large amounts of pirated software were more likely to be affected. "I think that piracy plays a role, though I don't know if it's the key contributor," Huger said.

Both researchers were waiting to see what hackers would do now that they have infected such a large number of computers. Earlier versions of Conficker tried to install a program called Antivirus XP, a notorious rogue antivirus program that infects victims' computers with pop-up messages in an attempt to trick them into paying for bogus software.

Researchers said the machines could be converted into what would be the world's largest botnet computer network or sold off piecemeal to criminals.

Infected computers are now regularly visiting about 500 rendezvous points on the Internet looking for instructions. When those instructions finally appear, computer experts will know more about what the worm was designed to do.

"It's a fantastic spread relative to other threats, and yet the author seems to have become suddenly self-conscious about updating," Huger said. "Maybe he's concerned about all the press it's getting and doesn't want to go to jail."