Cryptography Is Not Enough: Relay Attacks on Authenticated GNSS Signals

Abstract

Civilian-GNSS is vulnerable to signal spoofing attacks, and countermeasures based on cryptographic authentication are being proposed to protect against these attacks. Both Galileo and GPS are currently testing broadcast authentication techniques based on the delayed key disclosure to validate the integrity of navigation messages. These authentication mechanisms have proven secure against record now and replay later attacks, as navigation messages become invalid after keys are released. This work analyzes the security guarantees of cryptographically protected GNSS signals and shows the possibility of spoofing a receiver to an arbitrary location without breaking any cryptographic operation. In contrast to prior work, we demonstrate the ability of an attacker to receive signals close to the victim receiver and generate spoofing signals for a different target location without modifying the navigation message contents. Our strategy exploits the essential common reception and transmission time method used to estimate pseudorange in GNSS receivers, thereby rendering any cryptographic authentication useless. We evaluate our attack on a commercial receiver (ublox M9N) and a software-defined GNSS receiver (GNSS-SDR) using a combination of open-source tools, commercial GNSS signal generators, and software-defined radio hardware platforms. Our results show that it is possible to spoof a victim receiver to locations around 4000 km away from the true location without requiring any high-speed communication networks or modifying the message contents. Through this work, we further highlight the fundamental limitations in securing a broadcast signaling-based localization system even if all communications are cryptographically protected.

An Experimental Performance Assessment of Galileo OSNMA

“…While we use the term ‘authenticated positioning’, it should be noted that OSNMA at the moment can only authenticate the navigation data, and the PVT is still computed using unauthenticated ranging data. This caveat is also explained in the OSNMA receiver guidelines [ 2 ], and there have already been works where the unauthenticated ranging data are exploited to spoof receivers despite authentic navigation data [ 8 ]. While the positions we compute in this section cannot be considered fully authenticated, they are resilient against spoofing based on altering the navigation message.…”

“…Despite OSNMA being a relatively new and modern technology still in its test phase, there is already relevant literature related to it encompassing both theoretical work [ 4 , 5 , 6 , 7 , 8 , 9 ] and practical performance assessments [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. In addition to this, there are a few open-source implementations of the OSNMA protocol [ 22 , 23 , 24 , 25 ], and some companies already support it in some of their products, such as Septentrio [ 26 ].…”

Detecting Maritime GPS Spoofing Attacks Based on NMEA Sentence Integrity Monitoring

“…Meaconing can also be effective against encrypted signals, as the signal content remains unaltered [8]. Advanced forms of meaconing allow spoofing of arbitrary positions by individually delaying each signal [4]. However, a lock on all counterfeit signals is not guaranteed and depends on factors such as the target's speed [28].…”

“…Despite significant efforts by all GNSS operating stakeholders to upgrade security or deploy new, more secure generations of systems, civil GNSSs currently do not have sufficient security measures as practically demonstrated in the case of GPS [3]. However, cryptographically authenticated GNSS signals have also recently been shown to remain vulnerable to spoofing attacks [4].…”

Watch This Space: Securing Satellite Communication through Resilient Transmitter Fingerprinting

“…Finally, some attacks can be carried out without violating any cryptographic properties of the system. The authors of [12] show that precisely timed message replays can cause Global Navigation Satellite Systems (GNSS) to misreport the location of the receiver to an attacker-specified location. Since these attacks are carried out by simply introducing delay to messages rather than altering message contents, conventional cryptography does not protect against them.…”