Security attack analysis of safety systems

An analysis of the security threats from attack scenarios for a state of the art safety certified control system is done here in order to provide a realistic discussion of the risk that a hacker could endanger, even kill people or harm the environment by such means. The security discussion here is done from a practical hacker's point of view instead of an analytic categorization. We show that even if there are known issues of using these outside a protected network, the challenges that a hostile hacker faces are much larger than a typical case. Most safety communication protocols are a vulnerable point in the system, with higher risk of dangerous compromising than the safety devices. We show that the most likely outcome of hacking a safety system is bringing the system to fail safe state, harming the availability instead of the safety.