Fiber Optic Cables Turned Into Hidden Microphones to Spy on Private Conversations

A 2026 research paper demonstrates that common fiber-optic cables can be abused as covert acoustic sensors: by connecting a DAS system to the optical distribution network and hiding a 15-meter coiled fiber segment in a wall box, attackers can reconstruct speech and other indoor sounds with high fidelity (over 80% intelligibility) up to ~2 meters away and remain effective from up to 50 meters in the distribution network. The attack is stealthy (immune to RF detectors and ultrasonic jammers) and poses a significant privacy risk for sensitive environments; suggested mitigations include minimizing excess fiber loops inside rooms, sound-proofing, and installing optical isolators.