In global navigation satellite systems (GNSS), a spoofing attack attempts to deceive a GNSS receiver by broadcasting fake GNSS signals, structured to resemble a set of normal GNSS signals, or by rebroadcasting genuine signals captured elsewhere or at a different time. Spoofing attacks are generally hard to detect as adversaries generate counterfeit signals. These spoofed signals are challenging to recognize from legitimate signals, thus confusing ships' calculation of positioning, navigation, and timing (PNT). This means that spoofed signals may be modified in such a way as to cause the receiver to estimate its position to be somewhere other than where it actually is, or to be located where it is but at a different time, as determined by the attacker. One common form of a GNSS spoofing attack, commonly termed a carry-off attack, begins by broadcasting signals synchronized with the genuine signals observed by the target receiver. The power of the counterfeit signals is then gradually increased and drawn away from the genuine signals.

Even though GNSS is one of the most relied upon navigational systems, it has demonstrated critical vulnerabilities towards spoofing attacks. GNSS satellite signals have been shown to be vulnerable due to the signals’ being relatively weak on Earth’s surface. A reliance on GNSS could result in the loss of life, environmental contamination, navigation accidents, and financial costs. However, since 80% of global trade is moved through shipping companies, relying upon GNSS systems for navigation remains unavoidable.

All GNSS systems, such as the US GPS, Russia's GLONASS, China's BeiDou, and Europe's Galileo constellation, are vulnerable to this technique. In order to mitigate some of the vulnerabilities the GNSS systems face concerning spoofing attacks, the use of more than one navigational system at once is recommended.

The December 2011 capture of a Lockheed RQ-170 Sentinel drone aircraft in northeastern Iran may have been the result of such an attack. GNSS spoofing attacks had been predicted and discussed in the GNSS community as early as 2003. A "proof-of-concept" attack was successfully performed in June 2013, when the luxury yacht White Rose of Drachs was misdirected with spoofed GPS signals by a group of aerospace engineering students from the Cockrell School of Engineering at the University of Texas in Austin. The students were aboard the yacht, allowing their spoofing equipment to gradually overpower the signal strengths of the actual GPS constellation satellites, altering the course of the yacht.

In 2019, the British oil tanker Stena Impero was the target of a spoofing attack that directed the ship into Iranian waters where it was seized by Iranian forces. Consequently, the vessel including its crew and cargo were used as pawns in a geopolitical conflict. Several shipping companies with vessels navigating around Iranian waters are instructing vessels to transit dangerous areas with high speed and during daylight.

On October 15, 2023, Israel Defense Forces (IDF) announced that GPS had been “restricted in active combat zones in accordance with various operational needs,” but has not publicly commented on more advanced interference. In April 2024, however, researchers at University of Texas at Austin detected false signals and traced their origin to a particular air base in Israel run by the IDF.

In June 2017, approximately twenty ships in the Black Sea complained of GPS anomalies, showing vessels to be transpositioned miles from their actual location, in what Professor Todd Humphreys believed was most likely a spoofing attack. GPS anomalies around Putin's Palace and the Moscow Kremlin, demonstrated in 2017 by a Norwegian journalist on air, have led researchers to believe that Russian authorities use GPS spoofing wherever Vladimir Putin is located.

The mobile systems named Borisoglebsk-2, Krasukha and Zhitel are reported to be able to spoof GPS.