Physical eavesdropping is the unauthorized capture of speech using hidden hardware, such as a concealed recorder, microphone, or audio relay, instead of malware, network interception, or account compromise. Because the attack happens in the room, encrypted messaging, firewalls, and endpoint protection may not notice it.
This matters in cyber security because sensitive discussions often reveal strategy, credentials, incident details, or business plans before they are ever written down. Attackers may exploit insider access, visitor privileges, or poorly controlled conference rooms to place a covert device near meetings or AV equipment. Defenses include controlled-area policies, access logging, room sweeps, tamper checks on meeting hardware, strict visitor handling, and reducing exposure of highly sensitive conversations. In practice, physical eavesdropping sits at the intersection of physical security and insider-risk management: the breach path is a door, not a port.