Optical, Acoustic and Electromagnetic Vulnerability Detection for Information Security

The information interaction between the air-gapped internal network and the external Internet is only possible through authorized and strictly controlled methods. Attackers make use of the vulnerability to transmit information covertly by software-stimulated signals leakage, which vary from optical, acoustic to electromagnetic, so we need to find the vulnerabilities and protect them from malicious exploitation. In this paper, a simple and active method to detect these vulnerabilities is presented from an optical point of view, that is, the Light Emitting Diode (LED) status indicator and screen backlight are controlled to send information by frequency shift keying (FSK) or amplitude shift keying (ASK). Improved receiver is designed for acquisition of optical signals, and the vulnerability detection methods are unified for acoustic and electromagnetic vulnerability. The target signal is easily distinguished from the noise signal by the time-frequency domain characteristics, the hidden testing information is recovered by simple demodulation methods, and the mechanism of compromising emanation from digital signal is revealed. Several hidden features such as harmonics and intermodulation have been investigated, which can be used to detect optical, acoustic and electromagnetic vulnerability quickly. (paper)