Increasingly, the transportation industry has moved towards automation to improve safety, fuel efficiency, and system productivity. However, the increased scrutiny that automated vehicles (AV) face over functional safety has hindered the industry's unbridled confidence in self-driving technologies. As AVs are cyber-physical systems, they utilize distributed control to accomplish a range of safety-critical driving tasks. The Operation Systems (OS) serve as the core of these control systems. Therefore, their designs and implementation must incorporate ways to protect AVs against what must be assumed to be inevitable cyberattacks to meet the overall AV functional safety requirements. This paper investigates the connection between functional safety and cybersecurity in the context of OS. This study finds that risks due to delays can worsen by potential cybersecurity vulnerabilities through a case example of an automated vehicle following. Furthermore, attack surfaces and cybersecurity countermeasures for protecting OSs from security breaches are addressed.