Attacking mmWave Imaging Using Metasurfaces Based on Intensity and Time-of-Flight Manipulation

摘要

This paper proposes an efficient attack on millimeter-wave (mmWave) security screening systems by designing a novel reflective metasurface, termed MagicPatch, which is applied to prohibited items hidden under clothing and alters imaging results to resemble those of the human body, significantly reducing detection rates. In wideband mmWave imaging systems, MagicPatch is optimized in two key aspects: (1) tuning group delay parameters to manipulate the Time-of-Flight (i.e., perceived object distance); and (2) adjusting reflectivity to control the intensity of the reflected signals (i.e., material properties). To enable automated MagicPatch design, we propose a joint optimization framework that determines the optimal structural configurations of the MagicPatch for targeted attack scenarios, while supporting a low-cost fabrication process. Comprehensive experiments are conducted on two commercial mmWave security scanners with volunteers of diverse body types. The results demonstrate that the MagicPatch effectively conceals eight types of prohibited items with thicknesses ranging from 1 to 5 cm, achieving an alarm suppression rate of 85.7% to 97.0%, significantly higher than baseline methods at 9.4% to 36.7%.