Spatial Frequency Detection of Optical Signals Embedded in the Environment

Preventing the exfiltration of critical data via out-of-band channels is one of the most difficult challenges in cybersecurity. This challenge notably includes commu-nications utilizing optical channels. Numerous papers have suggested the modulation of indicator lights to transmit information out of otherwise secure networks. These means of optically embedding data are both challenging to detect and a threat to the security of confidential data. This paper presents a scalable, near-real-time process to detect and localize data hidden in optical channels amid other optical modulation, including electric network frequencies. Assumptions on the detectability of hidden optical channels are reviewed and a method of detecting and localizing transmissions based on spectral artifacts of embedded data is developed. Proof-of-concept experiments demonstrate the successful detection of potential optical data leaks in an office environment. This capability can allow for low cost optical bug sweeping devices, arming information security teams with a tool to detect and mitigate the insidious threat of optical out-of-band channels.