OT Control Tower - increase visibility of your critical OT assets and take control

Despite increased investments in digital transformation, many industrial organizations still lack a consistent, methodical approach to OT asset discovery, classification, and lifecycle management.

In conversations with clients and across multiple OT assessments, we continue to see:

• Fragmented OT inventories across plants and business units
• Unknown assets operating inside critical production networks
• Limited visibility of legacy equipment and unsupported systems
• Manual updates that quickly become outdated
• Missing correlations between assets, production processes, risks, vulnerabilities and incidents.

Without real-time visibility, teams cannot confidently answer fundamental questions: What do we have? Why do we have it? Where is it? What does it connect to? Is it secure?

Answering these fundamental questions in OT environments is significantly more complex. While IT environments have largely standardized around modern operating systems, agent-based tools, and mature lifecycle processes, OT operates under very different conditions — and cannot be treated the same.

Key differences include:

• Long asset life cycles (often 20 to 30 years)
• Proprietary protocols with minimal documentation and limited ability to respond to discovery prompts
• Legacy systems fragile to network scans
• Complex network architectures – not designed for asset discovery
• Strict availability requirements that restrict intrusive activities
• Decentralized responsibilities across engineering, production and IT teams

For these reasons, OT visibility typically requires a combination of discovery methods — each suitable for different parts of the environment.

Given the complexity of OT environments, no single discovery method is sufficient to achieve full asset visibility. In practice, organizations rely on a combination of complementary techniques, each addressing different parts of the environment and specific operational constraints.

1. Manual capture

It is essential for isolated networks or legacy systems that cannot be scanned.

It is used during commissioning or vendor handover, but is prone to gaps if not continuously updated.

2. Configuration analysis

Extracting information from:

• engineering workstation project files
• change management records
• vendor documentation.

Provides a useful context but depends on process maturity.

3. Agent‑Based Insights (Indirect)

While agents are not deployed on PLCs or RTUs, data from:

• servers
• engineering workstations
• patch management tools.

can enrich the OT asset picture.

4. Active identification

Controlled scans that query devices directly.

This method is accurate but risky for older OT systems and must be carefully governed.

5. Passive network monitoring

It is the safest and most widely adopted method in OT. By analyzing real network traffic, passive discovery tools identify:

• device types
• firmware
• communications
• vulnerabilities
• abnormal behavior.

This approach aligns well with industrial IDS and cyber monitoring deployments. However, organizations should be encouraged to consider OT asset discovery as a design requirement when selecting or deploying OT IDS solutions. In such cases, the resulting architecture and deployment model may differ from those intended for OT monitoring alone.

Regardless of the discovery approach used, one challenge remains consistent:

To develop accurate OT inventory and minimize operational risk, organizations today increasingly adopt a hybrid discovery approach. Passive monitoring remains the safest foundation, but on its own often lacks the detail required for complete asset intelligence. For this reason, many OT teams complement passive methods with carefully governed active or selectively‑active techniques that are specifically designed not to disrupt industrial processes.

Some OT assets — such as operator workstations, servers and newer controllers — can be actively scanned, but only after thorough verification and approval from engineering teams, as safety and process stability must always come first. Alternatively, deeper active identification can be performed during scheduled maintenance windows, when operational risk is reduced.

To support this hybrid model, key practices include:

• choosing solutions designed specifically for OT environments;
• using passive TAPs or SPAN ports to safely detect and classify OT assets based on real network communications;
• automate continuous discovery rather than rely on periodic snapshots;
• defining central governance, ownership and the roles responsible for sustaining the process;
• integrating OT data with IT and enterprise systems for context and action.

This blended model safeguards industrial processes while creating a more complete and trustworthy view of OT assets, providing the foundation needed for more connected, insight‑driven and resilient OT operations.

While some organizations maintain plant‑level inventories, increasing complexity and the need for enterprise‑wide visibility are driving a shift toward centralized OT asset management within an enterprise CMDB:

Local inventory

• Useful for plant engineering teams
• Limited visibility at the enterprise level
• Hard to scale, maintain, or correlate with risks

Central (CMDB‑Driven) Inventory

A centralized approach supports a wider range of operational and security processes:

• Change Management
• Vulnerability Response
• Incident Response and Forensics
• Risk and Compliance Management
• Reporting, KPIs, and ROI measurement

A unified view helps both plant-level and enterprise-level decisions.

In industrial environments, understanding asset relationships is as important as knowing the asset itself. A single outdated firmware version can impact an entire production line.

Service mapping tools can provide:

• hierarchical modelling of OT devices and production systems
• contextual visibility into upstream and downstream dependencies
• automatic mapping of equipment based on subnet or protocol logic
• integration with change, incident, vulnerability, and compliance workflows

This context transforms raw asset lists into operational intelligence — a critical foundation of an OT Control Tower.

To maximize its value, service mapping in OT should be enriched with process criticality derived from business impact analysis (BIA). This context enables better prioritization, risk-informed decision-making and more accurate impact assessment across industrial operations.

OT asset visibility is one of the foundational pillars of a modern OT Control Tower. However, achieving real operational value requires going beyond visibility alone — toward an integrated, platform‑based approach that combines asset data, process context, risk insights, and operational workflows.

ServiceNow provides a set of capabilities that support the development of a scalable, AI‑native OT management model by linking asset data with operational processes across the OT environment:

• OT Visibility
  Automated identification of assets using a combination of passive, active, and agent‑based discovery methods, forming the foundation for a trusted and continuously updated OT asset inventory.
• OT CMDB
  A dedicated OT data model supporting industrial asset classes, equipment model mapping and operational status management — enabling a centralized and consistent asset baseline across the enterprise.
• OT Service Management
  Supports structured OT operations through workflows such as incident, change, problem, and request management — aligning OT processes with enterprise service management practices.
• OT Asset Management
  Enables end‑to‑end lifecycle management of OT devices, including asset health monitoring, governance, and integration with operational processes.
  

Together, these capabilities enable organizations to evolve from fragmented visibility toward a fully integrated OT Control Tower, supporting data‑driven and risk‑informed operations at scale.

Fast, uncontrolled OT asset discovery can be risky — it may disrupt operations or miss critical dependencies.

But responsible, continuous, platform‑driven OT asset discovery and service mapping enables informed decision‑making without jeopardizing uptime.

Process maturity and clear ownership structures are essential to sustain these capabilities, ensuring that asset data remains accurate, actionable, and governed. 

Equally important is ensuring that engineering and OT security teams remain actively involved to validate findings, interpret context and oversee automated decisions.

ServiceNow® provides a unified way to discover OT assets, map industrial processes, monitor threats and connect insights with action.

This enables organizations to move from fragmented visibility to a fully governed, data‑driven OT environment — operating with greater confidence, resilience, and control.