More than 100 million messages contain attachments that, if opened, install software that takes over computers, security experts say.
A computer hacker calling himself Curador contends he stole the entire database of an unidentified Web store, making off with more than 5,000 credit card numbers. On Monday, Curador posted about 1,000 supposedly stolen card numbers on a personal Web site hosted by Xoom.com. The site since has been shut down. On a different site the next day, Curador posted what he claimed to be Microsoft founder Bill Gates's credit card number.
In a message on his site, Curador criticized Web site developers for overlooking the security holes that allowed him to hack into the sites. "Maybe one day people will setup their sites properly before they start trading because otherwise this won't be the last page I post to the Net," Curador wrote in his message.
The break-in comes on the heels of a hacking and extortion attempt at CDuniverse.com a few weeks ago.