Chinese hackers stole network diagrams, credentials, and personnel data in a breach that poses a threat to critical infrastructure nationwide.

The Chinese state-sponsored hacking group known as Salt Typhoon breached and remained undetected in a U.S. Army National Guard network for nine months in 2024, stealing network configuration files and administrator credentials that could be used to compromise other government networks.

A Department of Homeland Security memo from June, describing the Pentagon’s findings, said that the group, publicly known by the nickname Salt Typhoon, “extensively compromised a U.S. state’s Army National Guard network” from March 2024 through December 2024. The memo did not specify which state was affected.