As critical infrastructure sectors face escalating cyber and physical threats during their digital transformation, it is crucial to implement robust security strategies. Recognizing the unique challenges and architectures in securing these environments, the Cloud Security Alliance (CSA), an organization for defining standards, certifications, and best practices to ensure a secure enterprise computing environment, has released Zero Trust Guidance for Critical Infrastructure. This guidance explores the vital and nuanced application of Zero Trust (ZT) principles within operational technology (OT) and industrial control systems (ICS).
Developed by CSA’s Zero Trust Working Group, the paper lays out the foundational concepts of Zero Trust and provides a tailored roadmap for implementing these principles effectively in OT/ICS settings. The paper uses CSA’s recommended and repeatable five-step process for Zero Trust: define the protect surface (the area a ZT policy will protect), map operational flows, build a Zero Trust architecture, create Zero Trust policies, and monitor and maintain the network.
The process, which was originally outlined in the NSTAC Report to the President on Zero Trust and Trusted Identity Management, represents best practices for approaching Zero Trust projects, and with it, organizations can effectively mitigate risks and enhance the resilience of their CI.
“A Zero Trust strategy is a powerful means of fortifying critical OT/ICS systems against increasingly sophisticated adversaries as it can keep pace with rapid technological advancements and the evolving threat landscape,” said Jennifer Minella, a lead author of the paper and a member of the Zero Trust Working Group leadership team. “It’s our hope this set of guidelines will serve as a useful tool for communication and collaboration between those teams tasked with cybersecurity policies and controls and the system owners and operators of OT and ICS.”
Specifically, the document offers a detailed examination of the inherent differences between traditional IT and OT/ICS systems, focusing on aspects such as network design, device heterogeneity, and specific security requirements. Additionally, it provides a step-by-step implementation guide with actionable insights for each stage of deploying a ZT model in these unique settings. This includes specific guidance on identifying critical assets, mapping data flows, constructing a tailored ZT Architecture (ZTA), policy formulation, and the nuances of continuous monitoring within an OT/ICS context.
“In an environment where security is paramount and also distinctly challenging, Zero Trust is not just a security upgrade but a necessity. By delineating practical strategies and specific methodologies tailored for implementing a Zero Trust strategy into CI environments, we are helping to ensure resilience and security amidst a rapidly evolving digital technology and threat landscape,” said Joshua Woodruff, a lead author of the paper and a member of the Zero Trust Working Group leadership team.