The CISA Asset Inventory Requirement That Changed Everything For OT – And How to Actually Meet It

The cybersecurity landscape shifted in August 2025 when CISA, alongside the EPA, NSA, FBI, and five international cybersecurity agencies, released comprehensive guidance establishing operational technology (OT) asset inventory as an official Cybersecurity Performance Goal. This wasn’t a suggestion. It wasn’t a best practice recommendation buried in a lengthy advisory. It was a unified declaration from nine government agencies across six countries that OT asset inventory is now foundational to cybersecurity and critical infrastructure protection.

For many organizations, this announcement landed like a wake-up call in the middle of the night. For others, it crystallized a problem they’ve been struggling with for years: they don’t actually know what’s running in their OT environments.

At Asimily, we’ve spent years helping organizations answer this fundamental question. And we understand why it’s so hard. OT environments are impossibly complex—legacy systems running decades-old software, specialized industrial devices with proprietary protocols, sensors and instrumentation scattered across physical locations, and communication pathways that often weren’t designed with modern cybersecurity in mind. Creating a complete, accurate, and continuously maintained asset inventory across this landscape using manual processes, spreadsheets, and periodic physical inspections is a task that consumes months of effort and still leaves organizations blind to changes in real-time.

That’s where the CISA mandate becomes both a challenge and an opportunity.

Understanding the CISA Mandate

The August 2025 guidance isn’t vague or open-ended. CISA is explicit about what organizations need to do: create and maintain a comprehensive OT asset inventory supplemented by an OT taxonomy—a categorization system that organizes and prioritizes assets based on function and criticality. This inventory must include 14 high-priority attributes for every asset: active communication protocols, asset criticality, asset number, asset role/type, hostname, IP address, logging configuration, MAC address, manufacturer, model, operating system, physical location, ports/services, and user accounts.

The guidance also emphasizes that this isn’t a one-time exercise. Asset inventories must be continuously updated as systems change, new devices are added, and others are decommissioned. Organizations must implement lifecycle management policies that track assets from acquisition through deployment, commissioning, maintenance, and eventual decommissioning. And they must cross-reference their inventory against vulnerability databases like CISA’s Known Exploited Vulnerabilities (KEV) Catalog and MITRE’s CVE database to identify and prioritize at-risk systems.

For organizations that have been managing OT environments manually, this mandate presents an obvious problem: the resources required to meet these requirements are staggering. Hiring teams of engineers to conduct physical inspections, maintain spreadsheets, manually correlate vulnerability data, and update inventories every time something changes isn’t just expensive—it’s unsustainable.

Why Manual Asset Inventory Falls Short

Before we talk about solutions, let’s be honest about why manual asset inventory processes consistently fail to meet CISA’s requirements:

Discovery is incomplete. Physical inspections miss air-gapped systems, devices in remote locations, or assets that have been installed but not documented. Manual surveys rely on institutional knowledge that walks out the door when people leave. Network scans can identify some devices, but OT systems often run on proprietary protocols that standard scanning tools don’t recognize.

Attribute collection is inconsistent. Even when organizations successfully identify assets, collecting all 14 required attributes is tedious work prone to errors and omissions. Different teams may use different naming conventions, record information in different formats, or lack access to certain details (like manufacturer specifications for legacy equipment). The result is an inventory that’s incomplete, inconsistent, and difficult to use for security decision-making.

Updates lag reality. The moment an inventory is completed, it begins to drift. New devices are added during maintenance windows. Systems are patched or updated. Equipment is decommissioned. In traditional IT environments, change management processes might catch these updates. In OT environments, where uptime is measured in millions of dollars per hour and emergency changes are common, manual tracking simply can’t keep pace.

Vulnerability correlation is manual and slow. Even if you have a complete inventory, correlating it against vulnerability databases requires manual work or custom integration efforts. By the time you’ve identified which of your assets are vulnerable to a newly published exploit, attackers may already be exploiting it in the wild.

Context is missing. A list of assets with attributes isn’t the same as understanding your OT environment. You need to know which assets are critical to operations, how they communicate with each other, which systems would cause the most damage if compromised, and how attack pathways could move laterally across your network. A truly effective asset inventory—the kind CISA is asking for—must provide this contextual understanding.

This is why so many organizations, despite years of effort, still can’t answer the simple question: “What exactly do we have running in our OT network, and how vulnerable are we?”

How Asimily Solves the Asset Inventory Challenge

Asimily was built on a simple premise: you cannot secure what you can’t see, including your operational technology. Our platform delivers this visibility across six critical dimensions:

Automated Asset Discovery. Asimily discovers all OT assets across your entire environment without requiring operational downtime, physical inspections, or manual surveys. Our discovery engine works across legacy systems, proprietary protocols, and air-gapped networks. We identify devices that standard tools miss, such as the specialized industrial equipment, the decades-old systems that have been running unchanged for years, and the sensors and instrumentation that were never formally documented. And critically, this discovery happens continuously, so new devices are identified automatically as they’re added to your network.

Complete Attribute Collection. Every asset in your Asimily inventory includes all 14 CISA high-priority attributes, plus additional medium and low-priority fields for comprehensive visibility. We automatically capture manufacturer and model information, operating systems and firmware versions, IP and MAC addresses, communication protocols, ports and services, physical locations, and more. This isn’t data you have to manually enter or hunt for in vendor documentation—it’s collected automatically and normalized into a consistent format that actually works for security analysis.

Real-Time Continuous Monitoring. Your asset inventory stays current automatically. When new devices are added, we detect them. When systems are updated or patched, we see those changes. When equipment is decommissioned, we track that too. This means you’re never working with stale data or discovering months later that your inventory is out of sync with reality.

Integrated Vulnerability Management. Asimily automatically correlates your asset inventory with CISA’s KEV Catalog, MITRE’s CVE database, and other vulnerability intelligence sources. This means you instantly know which of your assets are vulnerable to known exploits, which vulnerabilities are actively being exploited in the wild, and which of your critical assets need immediate attention. Vulnerability management becomes actionable intelligence rather than a separate, disconnected process.

Protocol and Communication Visibility. Understanding what protocols your OT assets are using, and how they communicate with each other, is essential for both security architecture decisions and attack surface analysis. Asimily identifies all active communication protocols, documents data flows, and helps you understand the network dependencies that CISA’s guidance emphasizes as critical for effective segmentation and defense.

Taxonomy and Classification Support. Asimily enables you to organize and categorize your assets according to CISA’s recommended approaches. Whether you’re using criticality-based classification (high/medium/low), function-based classification, or the ISA/IEC 62443 zones and conduits model that CISA’s guidance references, Asimily provides the structure and flexibility to build a taxonomy that matches your environment and supports your security strategy.

From Mandate to Compliance in Weeks, Not Months

Here’s what this means in practical terms: instead of spending months on manual discovery, spreadsheet maintenance, and vulnerability correlation, organizations using Asimily can achieve complete CISA CPG compliance in weeks. And more importantly, they maintain that compliance continuously—not through constant manual effort, but through automated processes that run in the background.

The resources your team would have spent on manual asset inventory can now be redirected to what they should actually be doing: analyzing risk, implementing controls, hunting for threats, and improving your overall security posture.

Why This Matters Now

CISA’s August 2025 guidance isn’t just another cybersecurity recommendation. It represents a unified position from the highest levels of U.S. government and international cybersecurity agencies that OT asset inventory is foundational to critical infrastructure security. This guidance will likely become the basis for regulatory requirements, contractual obligations, and audit expectations across the energy, water, manufacturing, and other critical sectors.

Organizations that treat this as a checkbox exercise – creating a static inventory and then checking the box – will quickly find themselves falling behind as their environments change. Those that implement manual processes will burn through resources without ever achieving complete visibility. But organizations that automate asset inventory through platforms like Asimily will build the visibility foundation that CISA is asking for and that modern threats demand.

The Path Forward

If your organization hasn’t yet tackled the CISA asset inventory mandate, the time to start is now. If you’ve started but found yourselves bogged down in manual processes, there’s a better way. Asset inventory doesn’t have to be an enormous burden that consumes months of effort and produces results that are outdated before they’re even finished.

Asimily delivers a safe and comprehensive OT asset inventory that meets every CISA requirement. We give you the complete visibility your organization needs—and we do it in a way that actually scales with your environment rather than consuming your team’s entire capacity.

The question isn’t whether you can afford to implement automated asset inventory. The question is whether you can afford not to – especially now that CISA has made it a mandatory component of your cybersecurity program.

Let’s talk about how we can help you see everything in your OT environment and build the asset inventory foundation that modern cybersecurity demands. Request a demo today.