Are safety-critical systems really survivable to attacks?

Safety-Critical Systems (SCS) stand for those systems designed to tackle events that could potentially cause human injury or loss of life, significant property damage, financial loss, or damage to the environment, among others. Modern SCS are in transport, infrastructure, medicine, nuclear engineering, recreation, and many other fields. Nevertheless, SCS are prone to various attacks aiming to explore their inherent complexity and broad attack surface to jeopardize essential services and assets. Survivability is key to protecting SCS through integrating preventive, reactive, and tolerant defenses. This paper stands out by analyzing the survivability aspects of SCS under attack through a systematic literature review of recently published articles. Based on the review, we devise a classification to separate the studies that focus on survivability for SCS from those that deal with related aspects, such as resistance, recognition, or tolerance to attacks. Further, we expose literature limitations indicating why there is still no guaranteed survivability of SCS in the presence of attacks.