## 4 Current Security Challenges in Maritime Networks  
There is no standardized cybersecurity strategy for maritime transportation, which is a safety-critical activity. Cybersecurity attacks on shipping lines may have severe consequences, such as maritime accidents and supply chain disruptions. Cyber-attacks can have the most severe consequences as autonomous vessels become more prevalent [33]. The threat of maritime cyber-attacks adds a level of complexity to the traditional maritime threats of piracy, illegal activities, maritime terrorism, and accidents at sea. Digitalization, automation, and connectivity are increasingly prevalent in the global maritime sector. In recent years, cyber threats have increased significantly. In the past few years, cyber-attacks on shore-based maritime-related systems have increased nine-fold, while GPS and AIS spoofing have frequently been observed [34]. Infiltrating and controlling a commercial vessel in order to capsize, collide, or cause environmental damage is now well within the realm of possibility [34]. A variety of complex automated systems are installed on modern and autonomous ships, including navigation systems, radio detection and ranging (radar), automatic identification systems (AISs), communication systems, and control systems to control a wide range of electro-mechanical systems, including the main engine, generator, and converter drive. In modern ships, the extensive use of automation and IT systems presents new opportunities for hackers and malicious actors to implement cyber-attacks that could have catastrophic consequences and cause major safety losses [35]. The main goal of the attackers is to gain remote access to ships and vessels, extract sensitive and valuable information for future attacks, or disrupt the ship's operations by tampering with crucial components and rendering automated systems non-functional [36]. Below are some potential vulnerabilities, the consequences of an attack, and actual incidents that have been reported:  
* There is no authentication or integrity check on the AIS transponders, which makes them vulnerable to hacking, where they could be used to spread fake messages. Attackers use software-defined radios to transmit false man-in-the-water signals, enabling them to remain undetected and transmit false weather reports [35, 36]. * Navigation and GPS technologies are actively used in the maritime sector, which is a target for a number of cyber-attacks that aim to exploit design flaws in order to destabilize services that rely on them [37]. By spoofing GPS signals, attackers are able to reroute a vessel without triggering an alarm or alert. * Autonomous vessels depend on enhanced SATCOMs to transmit operational commands and sensor data, making them susceptible to cyber-attacks such as denial-of-service attacks and man-in-the-middle attacks [38]. * The maritime very-small-aperture-terminal (VSAT) is an essential component for high-speed data transmission during naval operations. However, it lacks authentication, encryption, security, or personal information verification, making all devices vulnerable to attacks at the implementation level. Attackers could send false signals or malicious codes to disable or compromise the system, potentially endangering the safe navigation of the vessel [39]. * It is common for the system to be run on old computers without security updates. It is possible to compromise the system when updating the maps by downloading them from the Internet or manually uploading them via USB. The use of this updated medium can expose the system to many security risks [40]. * Despite the fact that radar signals are harder to interrupt than satellite signals, they are still susceptible to interference and DDoS attacks. Radar can provide inaccurate information about nearby objects in the event of a cyber-attack due to false echoes caused by external radar waves. Inaccurate information can lead to ship collisions.