SAN FRANCISCO — The same Chinese hackers who breached the records of at least four million government workers through the Office of Personnel Management appear to have been responsible for similar thefts of personal data at two major health care firms, Anthem and Premera, according to cybersecurity experts.
The multiple attacks, which began last year and were all discovered this spring, appear to mark a new era in cyberespionage with the theft of huge quantities of data and no clear motive for the hackers.