U.S. hospital breach biggest yet to exploit Heartbleed bug-expert
August 20, 2014 at 02:25 AM EDT
Aug 20 (Reuters) - Hackers who stole the personal data of about 4.5 million patients of hospital group Community Health Systems Inc broke into the company's computer system by exploiting the "Heartbleed" internet bug, making it the first known large-scale cyber attack using the flaw, according to a security expert.