Hardened by Design: Applying the NSA’s OT Guidance with Cisco Security & Splunk

You can’t protect what you can’t see—and in OT, finding out can’t mean putting operations at risk. Controllers and other industrial systems may run for decades, often without the ability to support modern security tools or tolerate disruptive changes. The National Security Agency’s (NSA) new guidance offers operators a timely way to rethink protection around those realities: apply Zero Trust principles while keeping safety and availability in view. Why now? The NSA warns that attacks on critical infrastructure can threaten national and economic security, public health, and safety. It also points to adversaries using AI to speed up reconnaissance and exploit development, while OT environments face the enduring challenge of legacy technology. Released October 8, 2026, the guidance is a call to reduce the paths attackers could use to reach or move through critical systems—before an intrusion becomes an operational disruption. (Read the NSA announcement) What does the NSA Information Sheet “Hardening Department of War (DoW) Critical Operational Technology (OT) Environments with Zero Trust (ZT) Principles” cover? It distills the broader DoW Zero Trust guidance into 26 prioritized activities across ten areas: remote access, OT data, asset inventory, visibility, cyber threat intelligence, smart controller hardening, network segmentation and monitoring, engineering…