Nowadays, as the cyber-threat landscape is evolving and digital assets are proliferating and becoming more and more interconnected with the internet and heterogeneous devices, it is fundamental to be able to obtain a sensible measure of the security of devices, networks, and systems. Industrial cyber–physical systems (ICPSs), in particular, can be exposed to high operational risks that entail damage to revenues, assets, and even people. A way to overcome the open question of measuring security is with the use of security metrics. With metrics it is possible to rely on proven indicators that benchmark systems, identify vulnerabilities, and show practical data to assess the risk. However, security metrics are often proposed with specific contexts in mind, and a set of them specifically crafted for ICPSs is not explicitly available in the literature. For this reason, in this work, we analyze the current state of the art in the selection of security metrics and we propose a systematic methodology to gather, filter, and validate security metrics. Then, we apply the procedure to the ICPS domain, gathering almost 300 metrics from the literature, analyzing the domain to identify the properties useful to filter the metrics, and applying a validation framework to assess the validity of the filtered metrics, obtaining a final set capable of measuring the security of ICPSs from different perspectives.

The correct and efficient measurement of security properties is key to the deployment of effective cyberspace protection strategies. In this work, we propose GRAPH4, which is a system that combines different security metrics to design an attack detection approach that leverages the advantages of modern network architectures. GRAPH4 makes use of attack graphs that are generated by the control plane to extract a view of the network components requiring monitoring, which is based on the specific attack that must be detected and on the knowledge of the complete network layout. It enables an efficient distribution of security metrics tasks between the control plane and the data plane. The attack graph is translated into network rules that are subsequently installed in programmable nodes in order to enable alerting and detecting network anomalies at a line rate. By leveraging data plane programmability and security metric scores, GRAPH4 enables timely responses to unforeseen conditions while optimizing resource allocation and enhancing proactive defense. This paper details the architecture of GRAPH4, and it provides an evaluation of the performance gains it can achieve.