Analog Pin Directionality as an Exfiltration Attack Surface in Mixed-Signal ICs
Researchers demonstrate exfiltration through nominally input-only analog pins in mixed-signal ICs, recovering data at 10 kbps on a 55nm PPG front-end.
The paper identifies a directionality-based attack class in analog/mixed-signal (AMS) ICs where data-dependent circuit-offset modulation converts a nominally input-only pin into an outbound information channel. Three host conditions enable the attack: a closed-loop amplifier, an exposed amplifier input, and sufficiently high impedance at that pin. Silicon validation on a photoplethysmography analog front-end in 55nm CMOS showed exfiltration at up to 10 kbps with error-free PRBS recovery, under 0.001% area overhead, and only 0.03 dB SNR reduction.
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