FBI Calls Breach of Sensitive Agency Networks a ‘Major Incident’

The Federal Bureau of Investigation has concluded that last month’s breach of the networks it uses to manage wiretaps and other surveillance work qualifies as a “major incident,” signaling the severity of an intrusion that had already prompted the agency to launch a criminal probe and move to toughen cybersecurity.

An inquiry into abnormal activity on the compromised network was opened on Feb. 17, according to a notice to Congress from the Justice Department that was reviewed by Bloomberg News. The affected system contains sensitive law enforcement information, including data from electronic surveillance and personal identification information on subjects of ...