BitWhisper: Covert Signaling Channel between Air-Gapped Computers using Thermal Manipulations

摘要

It has been assumed that the physical separation (air-gap) of computersprovides a reliable level of security, such that should two adjacent computersbecome compromised, the covert exchange of data between them would beimpossible. In this paper, we demonstrate BitWhisper, a method of bridging theair-gap between adjacent compromised computers by using their heat emissionsand built-in thermal sensors to create a covert communication channel. Ourmethod is unique in two respects: it supports bidirectional communication, andit requires no additional dedicated peripheral hardware. We provideexperimental results based on implementation of BitWhisper prototype, andexamine the channel properties and limitations. Our experiments includeddifferent layouts, with computers positioned at varying distances from oneanother, and several sensor types and CPU configurations (e.g., VirtualMachines). We also discuss signal modulation and communication protocols,showing how BitWhisper can be used for the exchange of data between twocomputers in a close proximity (at distance of 0-40cm) at an effective rate of1-8 bits per hour, a rate which makes it possible to infiltrate brief commandsand exfiltrate small amount of data (e.g., passwords) over the covert channel.