Exfiltration of Data from Air-gapped Networks via Unmodulated LED Status Indicators

The light-emitting diode(LED) is widely used as an indicator on the information device. Early in 2002, Loughry et al studied the exfiltration of LED indicators[16] and found the kind of LEDs unmodulated to indicate some state of the device can hardly be utilized to establish covert channels. In our paper, a novel approach is proposed to modulate this kind of LEDs. We use binary frequency shift keying(B-FSK) to replace on-off keying(OOK) in modulation. In order to verify the validity, we implement a prototype of an exfiltration malware. Our experiment show a great improvement in the imperceptibility of covert communication. It is available to leak data covertly from air-gapped networks via unmodulated LED status indicators.