Charging Into Your Privacy: Indirect Privacy Leakage Attack Using a Laptop Charger

Can an everyday peripheral device, such as a laptop charger, function as an indirect side channel through which private user activities are exposed? In this paper, we propose PrivateCharger, a novel side-channel attack that affirms this possibility. By analyzing subtle variations in the magnetic field signals emitted by a laptop charger, PrivateCharger infers user activity without requiring any physical access to the laptop itself. Unlike prior work that targets internal components via power consumption or electromagnetic emissions, our approach shifts the attack vector to an external and previously overlooked component—the charger. This redirection enables stealthy inference from a distance, even outside the user's line of sight. Importantly, PrivateCharger operates using only commercially available devices, with no hardware modifications to the laptop or charger, significantly lowering the barrier to execution and enhancing real-world applicability. We evaluate our method across laptops with diverse hardware architectures and charger power ratings, achieving high recognition accuracy—especially at battery levels between 50% and 80%, where it reaches an average of 84.6% on two MacBook Pro models. Furthermore, we demonstrate the attack's robustness in complex real-world conditions, including multi-charger environments and concurrent application scenarios. These findings reveal that seemingly innocuous peripheral devices can serve as covert conduits for privacy leakage, expanding the threat landscape of passive sidechannel attacks in everyday computing environments.