Satellite systems are increasingly vulnerable to spoofing attacks at the physical layer, where adversaries use inexpensive radio equipment to interfere with and replace legitimate signals. While cryptographic countermeasures are common in other wireless systems, their adoption in new space programs is slow due to concerns about the associated implications on robustness, cost, weight, power, and the challenges of updating existing systems. In this paper we introduce SideDish, a novel anti-spoofing countermeasure that combines a secondary receiver colocated at the satellite receiver with decoded signal comparison to detect out-of-beam unauthentic interference. The system is retrofittable into existing ground station deployments, cheap by using only low-cost components, and is robust against denial of service attacks. We verify this through simulations and real-world experiments that show SideDish spatially constraints attackers by between 70-99.84% in the angular domain, even considering scattering effects of the primary antenna. Targeting SideDish to deny service is not feasible within practical constraints, requiring microsecond-order timing accuracy to overcome.

Motivated by the growing prevalence of increasingly advanced satellite jamming attacks, we introduce and systematically analyze protocol-aware jammers: the worst-case scenario that maximally exploits the protocol to deny service whilst remaining as difficult to detect as possible. This extends existing satellite jamming and anti-jamming literature, which to date considers only conventional jamming waveforms. We find that protocol-aware jammers are significantly more effective than conventional jammers against all major standardized satellite protocols, including when anti-jamming countermeasures in the form of interleaving and adaptive coding and modulation are employed. This performance is possible since current protocols have a cyclic and predictable nature. We assess the required capabilities in terms of synchronization, and show that many of these performance gains can be realized even by completely desynchronized jammers. We experimentally evaluate protocol-aware strategies against both a hardware and software receiver. The results show that over 15dB of performance gains over Gaussian jamming are possible against all tested satellite protocols. Furthermore, we find that the attack can be optimized in simulation and deployed against the hardware receiver without performance degradation. We conclude with a discussion of countermeasures, primarily at the protocol level, to improve the availability of these systems.

Satellite communications are increasingly crucial for telecommunications, navigation, and Earth observation. However, many widely used satellites do not cryptographically secure the downlink, opening the door for radio spoofing attacks. Recent developments in software-defined radio hardware have enabled attacks on wireless systems including GNSS, which can be effectively spoofed using only cheap hardware available off the shelf. However, these conclusions do not generalize well to other satellite systems such as high data rate backhauls or satellite-to-customer connections, where the spoofing requirements are currently unknown. In this paper, we present a systematic review of spoofing attacks against satellite downlink communications systems. We establish a threat model linking attack feasibility and impact to required budget through real-world experiments and channel simulations. Our results show that nearly all evaluated satellite systems were overshadowable at a distance of 1 km in the worst case, for a budget of ~2000 USD or less. We evaluate how key challenges surrounding modulation schemes, antenna directionality, and legitimate satellite signal strength can be overcome in practice through antenna sidelobe targeting, overshadowing, and automatic gain control takeover. We also show that, surprisingly, protocols designed to be more robust against channel noise are significantly less robust against an overshadowing attacker. We conclude with a discussion of physical-layer countermeasures specifically applicable to satellite systems which can not be cryptographically upgraded.