Modern systems and devices, including unmanned aerial systems (UASs), autonomous vehicles, and other unmanned and autonomous systems, commonly rely on the Global Positioning System (GPS) for positioning, navigation, and timing (PNT). Cellular mobile devices rely on GPS for PNT and location-based services. Many of these systems cannot function correctly without GPS; however, GPS signals are susceptible to a wide variety of signal-related disruptions and cyberattacks. GPS threat detection and mitigation have received significant attention recently. There are many surveys and systematic reviews in the literature related to GPS security; however, many existing reviews only briefly discuss GPS security within a larger discussion of cybersecurity. Other reviews focus on niche topics related to GPS security. There are no existing comprehensive reviews of GPS security issues in the literature. This paper fills that gap by providing a comprehensive treatment of GPS security, with an emphasis on UAS applications. This paper provides an overview of the threats to GPS and the state-of-the-art techniques for attack detection and countermeasures. Detection and mitigation approaches are categorized, and the strengths and weaknesses of existing approaches are identified. This paper also provides a comprehensive overview of the state-of-the-art on alternative positioning and navigation techniques in GPS-disrupted environments, discussing the strengths and weaknesses of existing approaches. Finally, this paper identifies gaps in existing research and future research directions.

The topic of Unmanned Aerial Vehicle (UAV) cybersecurity has received significant recent interest from the research community, with many methods proposed in the literature to improve detect and mitigate various types of attacks. This paper provides a comprehensive review of UAV cybersecurity, addressing all aspects of the UAV ecosystem and presenting a thorough review of the various types of UAV attacks, including a survey of recent real-world UAV cybersecurity incidents. UAV cybersecurity threat analysis and risk assessment methodologies are reviewed, discussing how potential attacks translate to UAV system risk. The various threat detection and countermeasure (mitigation) techniques are analyzed. Finally, this paper’s unique contribution is that it provides a survey of existing tools and datasets that are available to UAV cybersecurity researchers. A key identified research gap is the need to conduct real-world experimentation to validate proposed cybersecurity techniques. Many proposed approaches are computationally expensive or require additional redundant hardware onboard the UAV. Future research should focus on the development of lightweight methods that are practical for UAV adoption. Another key research gap is the relative lack of RemoteID cybersecurity research, despite its mandated adoption by UAVs. Lastly, this paper concludes that Global Positioning System (GPS)-related threats pose the greatest continued risk to UAVs.