UCLA

The ubiquity of printers in modern office spaces provides our motivation to design a covert channel based on the emanations of one particular class of these devices which uses inkjet technology. In this thesis, we demonstrate how a covert channel can be established by leveraging the acoustic emissions of inkjet printers to exfiltrate information from an air-gapped network. In essence, malware installed on a computer with access to a printer, but no access to the Internet, can inject certain imperceptible patterns into all documents being sent to the printer, so as to control the printing process in such a way that an acoustic signal is generated which can be captured with a nearby smartphone. Throughout this work, we demonstrate how people are unable to perceive these patterns under normal light conditions. Moreover, two distinct modulation schemes are proposed for our communication system and tests are carried out considering different types of document layouts, in distinct circumstances.