Hackers stole Social Security numbers, health histories and other highly sensitive data from more than 21 million people, the Obama administration said Thursday, acknowledging that the breach of U.S. government computer systems was far more severe than previously disclosed.
The scope of the data breach — believed to be the biggest in U.S. history — has grown dramatically since the government first disclosed earlier this year that hackers had gotten into the Office of Personnel Management’s personnel database and stolen records for about 4.2 million people. Since then, the administration has acknowledged a second breach of the systems housing private data that individuals submit during background investigations to obtain security clearances.
Numerous U.S. lawmakers have said China was behind the attack. But Michael Daniel, President Barack Obama’s cybersecurity coordinator, said the government wasn’t yet ready to say who was responsible.