Physical Layer Auditing: Diodes, Photodiodes, and Magnetic Fields

This article explores how audits can extend beyond software logs to the physical layer, using diodes and photodiodes to detect data flow and light emissions, and magnetic fields to monitor system activity. It argues that traditional audits miss these signals, which can reveal hidden devices or tampering. The piece is a continuation of a series on 'Shadow SCADA' and physical security auditing.