Kyungho Joo (Korea University), Wonsuk Choi (Korea University), Dong Hoon Lee (Korea University)
Recently, the traditional way to unlock car doors has been replaced with a keyless entry system which proves more convenient for automobile owners. When a driver with a key fob is in vicinity of the vehicle, doors automatically unlock on user command. However, unfortunately, it has been known that these keyless entry systems are vulnerable to signal-relaying attacks. While it is evident that automobile manufacturers incorporate preventative methods to secure these keyless entry systems, a range of attacks continue to occur. Relayed signals fit into the valid packets that are verified as legitimate, and this makes it is difficult to distinguish a legitimate request for doors to be unlocked from malicious signals. In response to this vulnerability, this paper presents an RF-fingerprinting method (coined “HOld the DOoR”, HODOR) to detect attacks on keyless entry systems, which is the first attempt to exploit RF-fingerprint technique in automotive domain. HODOR is designed as a sub-authentication system that supports existing authentication systems for keyless entry systems and does not require any modification of the main system to perform. Through a series of experiments, the results demonstrate that HODOR competently and reliably detects attacks on keyless entry systems. HODOR achieves both an average false positive rate (FPR) of 0.27% with a false negative rate (FNR) of 0% for the detection of simulated attacks corresponding to the current issue on keyless entry car theft. Furthermore, HODOR was also observed under environmental factors: temperature variation, non-line-of-sight (NLoS) conditions and battery aging. HODOR yields a false positive rate of 1.32% for the identification of a legitimated key fob which is even under NLoS condition. Based on the experimental results, it is expected that HODOR will provide a secure service for keyless entry systems, while remaining convenient.