Building a SOC for OT: Tools and Tips

The rapid digitization of industrial and critical sectors has dismantled once-rigid barriers between Information Technology (IT) and Operational Technology (OT) environments. While this convergence offers unprecedented operational insights, it also introduces hard-to-mitigate security risks. CISOs, IT Directors, Network Engineers, and Operators face increasing pressure to not only defend IT assets but also secure the fundamental processes that keep pipelines flowing, power grids operational, and transport networks running. In this post, we provide a rigorous analysis of building a Security Operations Center (SOC) tailored for OT ecosystems, focusing on essential technologies, historical context, and actionable recommendations.

The Evolution of Security Operations in OT Environments

Historically, OT networks operated in isolation—“air-gapped”—where security was often a low priority, and reliability and uptime reigned supreme. Classic SCADA (Supervisory Control and Data Acquisition) systems and PLCs (Programmable Logic Controllers) communicated using proprietary protocols (e.g., Modbus, DNP3) with minimal authentication, under the premise that physical isolation equaled security. This “security by obscurity” paradigm began crumbling as remote management and IT-OT integration increased.

As attacks like Stuxnet (2010), Triton (2017), and BlackEnergy (2015) demonstrated, OT is squarely in the crosshairs of sophisticated threat actors. The classic IT-centric SOC model—centered around log correlation, endpoint telemetry, and network forensics—cannot be transplanted wholesale to OT. Instead, it must be adapted, respecting operational constraints, legacy device limitations, and safety imperatives.

Core Architectural Principles for an OT-Focused SOC

1. Network Segmentation and Asset Visibility

A robust SOC program for OT starts with comprehensive visibility. This means continuous asset discovery across multiple layers—field devices, control systems, operator workstations, and supporting IT infrastructure.

• Passive Monitoring: Many OT devices cannot tolerate aggressive scanning. Use passive network discovery (e.g., span ports, network taps) to minimize disruption.

• Network Segmentation: Apply segmentation (e.g., IEC 62443 Zones & Conduits model) to limit lateral movement. Virtual LANs (VLANs), firewalls, and non-routable segments remain essential.

• Protocol Awareness: Monitoring tools must decode industrial protocols like CIP, PROFINET, and OPC-UA—far more challenging than classic TCP/IP traffic analysis.

2. Data Collection and Ingestion Pipeline

Traditional SOCs rely on logs from endpoints, servers, and applications—often lacking in OT. Instead, focus on:

• Network Traffic Analysis (NTA): Tools like Nozomi Networks, Claroty, and open source solutions like Zeek—with custom protocol dissectors—are powerful allies. For context, Zeek (formerly Bro, created in 1995) was one of the first open frameworks for network security monitoring—its modularity helps adapt to industrial protocols.

• Event Log Aggregation: Where available, gather logs from historian servers, HMI workstations, and OT-enabled Windows hosts, centralizing to a SIEM. Syslog and native Windows event channels are starting points, but ensure proper normalization for OT semantics.

• Asset Inventory Integration: Modern solutions should align asset identification with threat detection logic—knowing that an alert pertains to a PLC vs. a domain controller impacts your playbook choices.

3. Threat Detection and Response (TDR) in the Industrial Context

OT threat detection must balance sensitivity with operational predictability:

• Behavioral Baselines: Machine learning techniques—unsupervised, with strong feedback from OT operators—can help identify deviations in process logic or communication patterns. However, “anomaly” ≠ “threat” in deterministic OT systems; domain-expert validation is crucial.

• Playbooks & Runbooks: Automated playbooks should differ from IT. For example, isolating a misbehaving PLC might be unacceptable in critical process control. Response actions must be coordinated with OT engineers and business continuity teams.

• Threat Intelligence: Industrial threat intelligence (e.g., MITRE ATT&CK for ICS) informs detection engineering. Enrich context by mapping observed activity to ICS-specific TTPs (Tactics, Techniques, and Procedures).

Fusing IT/OT Collaboration in the SOC Lifecycle

IT/OT convergence often fails due to “two tribes” thinking: IT values confidentiality; OT prioritizes safety, continuity, and deterministic operation. Effective SOC programs bridge this gap:

• Integrated Governance: Develop unified incident response plans. IT and OT leadership must jointly review scenarios—e.g., ransomware affecting a historian server, vs. a compromised PLC with potential for kinetic impact.

• Liaison Roles: Embed OT-savvy engineers within the SOC, and vice versa, to accelerate knowledge transfer. Champions on both sides ease cultural friction and translate requirements.

• Realistic Tabletop Exercises: Run joint drills simulating both IT and OT ingress/egress vectors. Lessons learned must feed policy and tooling improvements.

Technology Stack Reference: Tools and Practices

1. Network Detection and Response (NDR):

• Nozomi Networks Guardian: Passive OT network detection, asset inventory, and anomaly alerting with industrial protocol support.

• Claroty xDome and Continuous Threat Detection (CTD): OT visibility, risk scoring, integration with SIEM/SOAR via APIs.

• Zeek with Custom Scripts: Open-source, with community support for industrial protocol parsers, enabling bespoke detections.

2. SIEM Platforms:

• IBM QRadar, Splunk, LogRhythm: All support some degree of OT log/flow data ingestion, with integration support for leading NDRs.

• Elastic Stack (ELK): Often used for customization-heavy environments due to modularity and search power.

3. Incident Management & Orchestration (SOAR):

• Palo Alto Cortex XSOAR, IBM Resilient: Playbooks can be tailored for OT-specific workflows. Strong integration with ticketing and notification tools is recommended.
  Note: Most SOAR platforms are IT-native; adapt response actions conservatively for OT environments to avoid unintended process disruptions.

Additional Reference: Protocol-Specific Deep Packet Inspection

• Wireshark with OT dissectors: Useful for ad-hoc deep analysis of protocol flows, provided by engineers with packet analysis skills.

• Security Onion: Open-source platform combining Zeek, Suricata, and full packet capture capabilities—excellent for pilot deployments and proof-of-concept work.

Recommendations and Next Steps

1. Conduct a Readiness Assessment: Map your OT asset inventory, understand critical processes, and document data sources available for monitoring.

2. Design Around Detection, Not Just Prevention: Perimeter barriers are only part of the story. Build a layered defense strategy that incorporates behavioral anomaly detection and rapid containment techniques tailored to OT risk tolerance.

3. Invest in Cross-Training: Upskill IT SOC staff in OT operational constraints, and immerse OT personnel in security best practices. This investment pays dividends in incident response effectiveness.

4. Pilot, Measure, Iterate: Start with passive monitoring pilots, tune with real operational data, and evolve detection logic with a “living lab” approach.

5. Plan for Crisis Communication: Define clear escalation paths, and ensure business continuity contingencies are OT-aware—particularly for scenarios with physical safety implications.

Conclusion

Building a Security Operations Center for OT environments is a nontrivial undertaking—it cannot be executed as a copy-paste of IT security playbooks. It requires close alignment with process engineers, careful tool selection with protocol and visibility depth, and an organization-wide commitment to both uptime and cyber-resilience. The journey is iterative and demands humility: your first detection use case will not be your last. But through deliberate design and cross-functional collaboration, a SOC can & must become a cornerstone for OT security.