IEC 61511-1 Ed. 2 is now out, and as I’ve mentioned previously on this blog, with new requirements for cybersecurity analysis for your safety instrumented systems. The new requirement makes it mandatory to perform a security risk and vulnerability assessment for your safety instrumented systems. It specifically requires you to identify threats, to assess impact and likelihood (or credibility), and to plan your mitigation strategy and response to identified threats. The standard allows you to use an overall cybersecurity assessment for your entire control system, provided you cover all relevant threats for the SIS.
It is important to tailor the approach to the setting and the need in the network environment where the SIS is operated. It is possible to go into a vulnerability study at great detail, developing attack trees for low-level attack scenarios. From a SIS design point of view this is not very useful – and a more conceptual level assessment based on network topologies, security policies and the risk context of the plant is more appropriate.
At LR I’ve had the pleasure of adapting a more in-depth cybersecurity assessment method to the SIS environment together with some of my great colleagues, and we are looking forward to serving our customers with this as a part of functional safety management.
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