More than 10,000 website databases have been taken hostage in recent days by attackers who are demanding hefty ransoms for the data to be restored, a security researcher said Friday.

Unable to boot his HP Pavilion desktop computer, he sought the assistance of the store's Geek Squad. At the time, nobody knew the company's repair technicians routinely searched customers' devices for files that could earn them $500 windfalls as FBI informants. This case produced that national revelation.