OT Cybersecurity: Is the Purdue Model Still Useful?

Is the Purdue Model outdated, or simply misunderstood? In this episode, Dino sits down with Ken Kully (Rockwell Automation) for a candid, practitioner-level conversation about what the Purdue Model still gets right.

They discuss where it falls short in modern environments, and why “IT/OT convergence” remains more of a people-and-process challenge than a technology problem.

They break down the reality on the plant floor: long-lived legacy systems, inconsistent architectures across sites, limited maintenance windows, and the operational consequences of downtime.

The discussion also tackles the everyday friction points: MFA, shared operator accounts, unmanaged vendor laptops, and remote access “surprises”, and why you can’t improve OT security posture without a trustworthy asset inventory and segmentation that keeps systems “in their lane.”

Chapters:

• (00:00:00) Intro + why this Purdue conversation matters now
• (00:01:00) Ken’s background: from process environments to OT cyber delivery readiness
• (00:04:00) The big question: has the Purdue Model outlived its usefulness?
• (00:07:00) Framework vs. strict blueprint: “Purdue enough” in real plants
• (00:09:00) IT/OT convergence: why it’s a people + process problem (not tech)
• (00:12:00) The “silver tsunami” and why security UX fails on the plant floor
• (00:15:30) MFA, shared logins, and why “security gets in the way” still shows up
• (00:18:00) Legacy reality: Windows 98/7 boxes, vendor lock-in, and downtime economics
• (00:21:00) Discovery first: diagrams, configs, and why documentation is always missing
• (00:23:30) Purdue as a map: brokering traffic, one-up/one-down, and the “3.5” DMZ
• (00:26:00) When devices try to “escape the box”: unexpected outbound comms + exposure risk
• (00:28:30) Vendor/OEM access: the unmanaged laptop problem in OT
• (00:32:00) Asset inventory as the unlock: you can’t defend what you don’t know exists
• (00:34:00) Why IT often won’t “crawl the plant,” and what that means operationally
• (00:36:30) Scale problem: 30 plants, 30 realities—standardize globally, execute locally
• (00:38:30) The SI/OEM “third leg”: why trusted integrators are key to sustainable OT security
• (00:40:30) Closing + crossover: continuing the discussion on Ken’s OT After Hours podcast

Links And Resources:

• Kenneth Kully on LinkedIn
• Want to Sponsor an episode or be a Guest? Reach out here.
• Industrial Cybersecurity Insider on LinkedIn
• Cybersecurity & Digital Safety on LinkedIn
• BW Design Group Cybersecurity
• Dino Busalachi on LinkedIn
• Craig Duckworth on LinkedIn

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