2019/11/01 by Mordechai Guri, Dima Bykhovsky, Yuval Elovici
Computer Science · #Advanced Data Storage Technologies #Brightness #Computer graphics (images) #Computer science #Image and Video Quality Assessment #Interactive and Immersive Displays #Operating system #Optics #Physics #Workstation #cs.CR
paper · pdf · doi:10.1109/cmi48017.2019.8962137
2019 12th CMI Conference on Cybersecurity and Privacy (CMI)
openalex publication_date 2019/11/01 · openalex created_date 2020/01/30 · arxiv created 2020/02/04 · arxiv updated 2020/02/05 · openalex updated_date 2026/08/05
Air-gapped computers are systems that are kept isolated from the Internet since they store or process sensitive information. In this paper, we introduce an optical covert channel in which an attacker can leak (or, exfiltlrate) sensitive information from air-gapped computers through manipulations on the screen brightness. This covert channel is invisible and it works even while the user is working on the computer. Malware on a compromised computer can obtain sensitive data (e.g., files, images, encryption keys and passwords), and modulate it within the screen brightness, invisible to users. The small changes in the brightness are invisible to humans but can be recovered from video streams taken by cameras such as a local security camera, smartphone camera or a webcam. We present related work and discuss the technical and scientific background of this covert channel. We examined the channel's boundaries under various parameters, with different types of computer and TV screens, and at several distances. We also tested different types of camera receivers to demonstrate the covert channel. Lastly, we present relevant countermeasures to this type of attack.