A Study on Malicious Attacks for RIS-Aided Wireless Systems

Reconfigurable intelligent surfaces (RIS) aim to reconfigure the random channel between the source and the destination, thus directing the transmitted signals toward the destination. The potential gains of RIS-aided systems compared to legacy systems are an increase in rate, energy efficiency, and energy transfer. A RIS should be low-complex and quasi-passive, therefore, does not have a high computational capability. The source configures the phases of the RIS elements by sending a signal to its controller to maximize the required metrics, such as the received power, the rate, the signal-to-noise ratio (SNR), etc. However, the channel between the source and the RIS controller is vulnerable. In this paper, we discuss the security issues in RIS-aided wireless systems. We focus on the channel between the source and the RIS controller. We show that a severe decrease in the destination rate, to a value lower than the one of the system without RIS, can be made by controlling the phase shifts of the RIS. With a realistic 3GPP channel model and an RIS with 100 elements, the rate can be decreased from 4.55 bps/Hz to only 0.08 bps/Hz by selecting the RIS phase shifts to minimize the received power (power loss around 26 dB). Future directions and challenges are also discussed, such as energy deviation, multiple RISs, and multiple operators.

I. Introduction

Reconfigurable intelligent surfaces (RIS) aim to reconfigure the random channel between a source and a destination to make it directional [1]–[4]. The reconfiguration is to be done wisely by the source to maximize the intended performance metrics such as rate, signal-to-noise ratio (SNR), received power, etc. The source has to select the phase shifts of the RIS elements based on the channel state information (CSI) of the links between itself, the RIS, and the destination [5], [6]. The source sends these phase shifts to the RIS controller, which applies them to the RIS elements until a new configuration is sent. The benefits of RISs in improving the rate and the power received at the destination have been demonstrated in many papers [1]–[3], [5]–[7]. Some RIS implementations are also presented in [8]. For these reasons, RISs are considered one of the main enablers of 6G wireless systems [9], in addition to hybrid architectures [10], and massive multiple input multiple output systems [11].