Evaluation of GPS Signal Vulnerabilities against Time Synchronization Attacks

A spoofing attack is an intervention aimed at forcing the GPS receiver to obtain and track invalid navigation data. Time Synchronization Attack (TSA) is a type of spoofing attack that changes the receiver clock information, such as clock offset and drift. The purpose of TSA is to create an error in the estimated time of the receiver. These attacks usually target static receivers that use GPS signals for their time-synchronization applications. One of the main countermeasures for any security vulnerabilities is comprehending the process of thread generation and weak points of the system. In this research, for the first time, theephemeride TSA generation process is discussed and explained in detail. The proposed method demonstrates the feasibility of a spoof attack on the GPS receiver. The attack is defined as an optimization problem that aims to maximize the receiver clock offset error while maintaining the receiver position. The decision variables in the optimization problem are the coordinates of the receiver and the satellite's ephemerides variables. The constraints are such that the decision variables and satellite positions calculated from solving the optimization problem are close to pre-attack values to avoid possible detection schemes that examine large mutations in the values of these variables. Due to the ability to solve complex problems, simple concepts, and easy implementation of Metaheuristic Optimization Algorithms (MOA), Chimp Optimization Algorithm (ChoA), Grey Wolf Optimization (GWO) and Particle Swarm Optimization (PSO) algorithms are exploited. According to the achieved solutions, the maximum modification in the receiver clock offset is 1.6 ms, which is a severe attack based on IEEE C37.118 standard. This result is achieved despite a change of 10 meters in the coordinates of the receiver position.