U.S. Treasury Secretary Janet Yellen's computer was hacked and unclassified files were accessed as part of a broader breach of the Treasury Department by Chinese state-sponsored hackers, Bloomberg News reported on Thursday,

The US Treasury Department announced in a letter back in December that it had been the victim of a security breach, attributing it to a “China state-sponsored Advanced Persistent Threat actor.” Now we know more about the extent of the hack,

According to sources familiar with the breach cited in a Bloomberg report, hackers accessed fewer than 50 unclassified files on Yellen’s device.

Fewer than 50 files on Yellen’s machine were accessed by attackers, who failed to penetrate the department’s email or classified systems.