Cetratus: A framework for zero downtime secure software updates in safety‐critical systems

Abstract

SummarySafety‐critical systems are evolving into complex, networked, and distributed systems. As a result of the high interconnectivity among all networked systems and of potential security threats, security countermeasures need to be incorporated. Nonetheless, albeit cutting‐edge security measures are adopted and incorporated during the system development, such as latest recommended encryption algorithms, these protection mechanisms may turn out obsolete because of the long operational periods. New security flaws and bugs are continuously detected. Software updates are then essential to restore the security level of the system. However, system shutdowns may not be acceptable when high availability is required. As expressed by the European Union Agency for Network and Information Security (ENISA) “the research in the area of patching and updating equipment without disruption of service and tools” is needed. In this article, a novel live updating approach for zero downtime safety‐critical systems named Cetratus is presented. Cetratus, which is based on a quarantine‐mode execution and monitoring, enables the update of non‐safety‐critical software components while running, without compromising the safety integrity level of the system. The focus of this work lies on the incorporation of leading‐edge security mechanisms while safety‐related software components will remain untouched. Other non‐safety‐related software components could also be updated.

Cetratus: Live Updates in Programmable Logic Controllers

“…Secondly, the current PN state is updated. This process is also known as state transformation [6], [7]. For this purpose, the old PN marking is wrapped and transferred to the secondary container.…”

“…In this paper, a live updates concept for industrial Programmable Logic Controllers (PLCs) is proposed, which enables zero downtime reconfiguration capabilities and therefore, reduces the manufacturing system reconfiguration times and costs. The presented approach is based on the Cetratus framework [6], [7], originally devised for safe and secure industrial control systems, for example railway [7] or smart energy [8] systems. Even though the proposed framework was focused on the incorporation of leading-edge security mechanisms, any other types of software components could be updated.…”

Adaptive On-the-Fly Changes in Distributed Processing Pipelines

“…Similarly, Hicks and Nettles (2005) have described an approach where they used the C-like language Popcorn, compiling code patches into Typed Assembly Language that can be dynamically linked and integrated. There are other works on a language level like (Mugarza et al, 2020), which are implemented on the Ada programming language. Alternatively, Bagherzadeh et al (2020) present a language-independent approach based on model execution systems (Hojaji et al, 2019).…”

Safe and secure software updates on high-performance mixed-criticality systems: The UP2DATE approach

“…For this purpose, state information transferring procedures are executed. The update manager just swaps the old image by the new one, once the quarantine period of the verification ends [21,22].…”