The internal records of as many as 25,000 Homeland Security Department employees were exposed during a recent computer break-in at a federal contractor that handles security clearances, an agency official said Friday.
The official, who spoke on condition of anonymity to discuss details of an incident that is under active federal criminal investigation, said the number of victims could be greater. The department was informing employees whose files were exposed in the hacking against contractor USIS and warning them to monitor their financial accounts.
Earlier this month, USIS acknowledged the break-in, saying its internal cybersecurity team had detected what appeared to be an intrusion with “all the markings of a state-sponsored attack.” Neither USIS nor government officials have speculated on the identity of the foreign government. A USIS spokeswoman reached Friday declined to comment on the DHS notifications.