In this paper, we present Fansmitter, a malware that can acoustically exfiltrate data from air- gapped computers, even when audio hardware and speakers are not present. Our method utilizes the noise emitted from the CPU and chassis fans which are present in virtually every computer today. We show that a software can regulate the internal fans' speed in order to control the acoustic waveform emitted from a computer. [...] We demonstrated the effective transmission of encryption keys and passwords from a distance of zero to eight meters, with bit rate of up to 900 bits/hour.
Acoustic Data Exfiltration from (Speakerless) Air-Gapped Computers