Technical Surveillance Countermeasures (TSCM) is the practice of finding, assessing, and reducing technical surveillance threats. It covers classic risks such as hidden microphones, cameras, radio transmitters, and wired taps, but it also includes modern endpoints like smartphones and connected devices that can record, store, or relay sensitive information.
TSCM matters because surveillance is not only a physical problem; it is also a communications and device-hygiene problem. In practice, defenders use inspections, RF sweeps, access control, policy checks, and environmental reviews to identify collection paths. Attackers may exploit unsecured rooms, compromised mobile devices, or always-on sensors to capture conversations and metadata. Good TSCM therefore works alongside mobile security, encryption, and clean-room procedures to limit what can be observed, transmitted, or exposed in sensitive spaces.