Please use this identifier to cite or link to this item: https://dl.ucsc.cmb.ac.lk/jspui/handle/123456789/4916
Title: Covert Data Exfiltration from Smartphones through mmWave FMCW Radar
Authors: Dhatchaya, P.
Issue Date: 28-Jun-2025
Abstract: Abstract This research explores a novel covert communication method using smartphonegenerated vibrations detected by millimeter-wave (mmWave) Frequency-Modulated Continuous Wave (FMCW) radar. Traditional covert channels rely on internet connectivity, sound, or proximity-based methods that can be disabled or monitored. In contrast, this work demonstrates a contactless, connectivity-free covert channel using only the smartphone’s vibration motor and mmWave radar, aiming to assess its feasibility and cybersecurity implications. To achieve this, we developed a custom On-Off Keying (OOK) encoding scheme with a symbol duration of 80ms, with optimized vibration intensity to ensure that vibrations remain imperceptible to users while still being detectable by the radar.The evaluation of our system focused on two main aspects: the stealthiness of the covert channel and the technical feasibility of using mmWave radar to extract data. To assess stealth, qualitative tests with human participants were conducted to verify that the vibration signals remained imperceptible across common surfaces and at reduced amplitude levels. For technical feasibility, Experiments were conducted across five different Google Pixel smartphone models , distances ranging from 0.6m to 3.4m, different encoding schemes, device orientations, and through common household barriers such as cardboard, plastic, and glass. The mmWave radar setup, operating at 77GHz captured vibration signals for decoding. Results show that the radar achieves a 0% Bit Error Rate (BER) at distances up to 3.1m under line-of-sight conditions. At 3.4m, the BER increases significantly to approximately 56.25%. Experiments involving physical barriers revealed that thin materials allow reliable decoding, while thicker or denser barriers lead to noticeable performance degradation. Despite these limitations, the system maintained a data rate of 12.5bps under optimal conditions, enabling covert data transmission without triggering user suspicion or requiring any connectivity. These findings confirm that mmWave radar can be repurposed as a covert receiver for vibration-based data transmission. This work contributes to cybersecurity research by identifying and demonstrating a novel covert-channel threat and highlights the urgent need for new security mechanisms that consider non-traditional sensing technologies in threat models.
URI: https://dl.ucsc.cmb.ac.lk/jspui/handle/123456789/4916
Appears in Collections:2025

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