The Office of Personnel Management has fallen victim to a breach that U.S. authorities believe as the work of Chinese government-sponsored hackers, the Washington Post reported Thursday.
Ellen Nakashima writes OPM discovered the intrusion in April and said it will inform approximately 4 million former and current federal employees whose personal information may have been exposed.
Josh Campbell, an FBI spokesperson, told The Post that the bureau is working with OPM and the Department of Homeland Security to investigate the attack.
U.S. government officials revealed that intruders used a zero-day to access confidential worker records, according to the newspaper.
The Wall Street Journal reported the Einstein federal network monitoring system helped locate the breach on an Interior Department data center that stores OPM data.
Security firm iSight Partners is examining a possible link between the OPM intrusion and recent attacks at health insurance companies Anthem and Premera Blue Cross, according to WSJ.
Last year, OPM’s computer systems were breached by hackers targeting data on security clearance applicants and authorities also linked the incident to China.