FBI Probes Suspicious Activity on Sensitive Network

The Federal Bureau of Investigation disclosed this week that it is examining suspicious activities on an internal network system containing sensitive data related to surveillance operations and criminal investigations. The probe, which began on February 17 after officials noticed abnormal log information, involves an unclassified system targeted by advanced techniques that exploited security controls, according to a notification sent to members of Congress.

The affected system holds law enforcement sensitive information, including results from legal surveillance tools such as pen registers and trap and trace devices, as well as personally identifiable details about individuals under FBI investigation. A pen register allows authorities to record numbers dialed from a specific phone line without capturing the content of communications. The notification, reviewed by journalists, indicates that the intruder employed sophisticated methods, including the use of a commercial internet service provider's vendor infrastructure to bypass FBI network protections. Officials have not identified the perpetrator or attributed the incident to any specific actor.