Operational Technology Security:

Protecting Physical Infrastructure in a Digital World

By Tom Glover, Chief Revenue Officer at Responsive Technology Partners

The Merging of Two Worlds

For decades, information technology (IT) and operational technology (OT) existed in separate realms. IT systems managed data, while OT systems controlled physical processes and equipment. The air gap between these systems provided a natural security boundary. That era is over.

The convergence of IT and OT has created unprecedented opportunities for efficiency and innovation. Manufacturing floors now connect to enterprise networks. Power grids communicate with cloud servers. Building management systems integrate with corporate IT infrastructure. However, this interconnectivity has also opened critical infrastructure to new vulnerabilities.

This convergence presents unique security challenges that traditional IT security approaches cannot fully address. As organizations continue to digitize their physical operations, protecting OT infrastructure requires specialized knowledge and strategies.

The Stakes Are Higher Than Ever

When a data breach occurs in traditional IT systems, the consequences are serious but largely financial and reputational. When OT systems are compromised, the results can be catastrophic—production lines halt, utilities fail, or safety systems malfunction.

Consider the real-world examples we’ve witnessed in recent years:

• A water treatment facility in Florida experienced an intrusion where attackers attempted to increase sodium hydroxide to dangerous levels in the water supply
• The Colonial Pipeline ransomware attack disrupted fuel delivery to the eastern United States
• The infamous Stuxnet malware damaged Iranian nuclear centrifuges
• The NotPetya attack caused operational disruptions at shipping giant Maersk

These aren’t just cybersecurity incidents; they represent threats to physical safety, critical infrastructure, and economic stability. The security of OT systems is a matter of public interest and, increasingly, national security.

Understanding the OT Security Landscape

Operational technology encompasses a broad range of systems that monitor and control physical processes, including:

• Supervisory Control and Data Acquisition (SCADA) systems
• Distributed Control Systems (DCS)
• Programmable Logic Controllers (PLCs)
• Industrial Control Systems (ICS)
• Building Management Systems (BMS)
• Medical devices and healthcare systems
• Energy management systems

These systems have fundamentally different priorities than traditional IT. While IT security typically prioritizes confidentiality first (the CIA triad of confidentiality, integrity, availability), OT security flips this model. For operational technology, availability and integrity come first—these systems must remain operational and trustworthy, often at all costs.

The Unique Challenges of OT Security

Securing operational technology presents distinct challenges that make conventional IT security approaches insufficient:

Legacy Systems and Extended Lifecycles

Many OT systems were designed decades ago with 15-30 year operational lifespans, long before cybersecurity was a consideration. These systems often run on outdated, unpatched operating systems that cannot be easily updated without disrupting critical operations.

I recently worked with a manufacturing firm whose production floor relied on PLCs installed in the 1990s. These controllers ran proprietary firmware that hadn’t been updated in over a decade, yet they couldn’t be replaced without shutting down production for weeks—an unacceptable business disruption.

Limited Resources and Computing Power

Unlike modern servers or workstations, many OT devices have limited computing resources. They lack the processing power to run traditional security tools like endpoint protection or encryption. Adding security measures can impact performance, potentially causing operational issues.

Diverse Protocols and Proprietary Systems

The OT landscape uses numerous proprietary protocols (Modbus, DNP3, BACnet, etc.) that IT security tools aren’t designed to monitor or protect. These protocols often lack basic security features like authentication or encryption, having been designed for reliability in closed environments, not security in connected ones.

Operational Requirements and Downtime Constraints

While IT systems can often be taken offline for maintenance or updates, OT systems frequently require continuous operation. Patching vulnerabilities might require shutting down a production line or taking critical infrastructure offline—decisions with significant operational and financial implications.

Safety-Critical Systems

Perhaps most importantly, OT systems often control physical processes where failures could endanger human lives. Security measures must be implemented with extreme caution to avoid inadvertently affecting safety systems.

Building an Effective OT Security Strategy

Protecting operational technology requires a specialized approach that recognizes its unique requirements while adapting proven security principles.

1. Inventory and Visibility

You can’t protect what you don’t know exists. A comprehensive inventory of all OT assets is the foundation of effective security. This inventory should include:

• All networked devices and controllers
• Communication pathways between systems
• Connections to IT networks or external systems
• Firmware versions and patch levels
• Known vulnerabilities

Network monitoring tools specifically designed for OT environments can provide visibility without disrupting operations. These tools passively monitor network traffic, identifying devices and potential anomalies without sending active probes that might disrupt sensitive systems.

2. Segmentation and Defense-in-Depth

Network segmentation remains one of the most effective strategies for protecting OT environments. By implementing zones and conduits according to standards like IEC 62443, organizations can contain potential breaches and limit lateral movement.

Proper segmentation includes:

• Physical separation where possible
• Logical separation using VLANs and firewalls
• Data diodes for one-way information flow from critical systems
• Demilitarized zones (DMZs) between IT and OT networks
• Jump servers and access controls for administrative connections

This defense-in-depth approach ensures that no single security failure leads to a complete compromise.

3. Risk-Based Security Controls

Since patching and traditional security measures may not be feasible for all OT systems, a risk-based approach is essential. This means:

• Identifying your most critical assets
• Assessing threats and vulnerabilities specific to those assets
• Implementing compensating controls where traditional security measures aren’t possible
• Prioritizing security investments based on risk reduction rather than compliance checklists

For example, if a critical controller can’t be patched, additional network monitoring, access controls, and anomaly detection might provide compensating protection.

4. Secure Remote Access

The pandemic accelerated remote operations, making secure remote access to OT systems essential. However, this access must be carefully controlled through:

• Multi-factor authentication for all remote connections
• Time-limited access privileges
• Session recording and monitoring
• Secure VPN connections with encryption
• Vendor access management and monitoring

Remote access should always be explicit—allowed only when necessary, for specific purposes, and with proper authorization.

5. Supply Chain Security

OT systems often rely on specialized hardware and software from various vendors, creating supply chain risks. Mitigation strategies include:

• Vendor security assessments and contractual requirements
• Firmware verification before installation
• Monitoring for counterfeit components
• Change management procedures for vendor-supplied updates
• Contingency planning for vendor security incidents

The SolarWinds breach demonstrated how supply chain compromises can provide attackers with privileged access to critical systems. OT environments are equally, if not more, vulnerable to such threats.

6. Incident Response Planning

Despite best efforts, security incidents will occur. Planning specifically for OT security incidents is crucial, as the response differs significantly from IT incidents. An effective OT incident response plan should:

• Define roles and responsibilities across both OT and IT teams
• Establish communication protocols, including operational leadership
• Include procedures for isolating affected systems while maintaining critical operations
• Provide decision frameworks for operational continuity vs. security containment
• Include regular tabletop exercises that simulate OT-specific scenarios

7. Workforce Development and Culture

Security awareness takes on new dimensions in OT environments. Engineers, operators, and maintenance personnel need security training specific to their operational roles. Building a security-conscious culture means:

• Developing OT-specific security policies and procedures
• Training that addresses operational realities, not just IT security principles
• Creating clear escalation paths for security concerns
• Fostering collaboration between IT security teams and operational teams
• Recognizing and rewarding security-conscious behavior

The Path Forward: Convergence of Security Expertise

As IT and OT systems continue to converge, so too must security practices. This doesn’t mean simply applying IT security controls to OT environments. Rather, it requires a thoughtful merging of disciplines:

• IT security professionals need to understand operational requirements and constraints
• OT engineers need to incorporate security thinking into system design and maintenance
• Management needs to support cross-functional teams and initiatives
• Security frameworks need to accommodate both IT and OT requirements

The most successful organizations are creating integrated teams that bring together IT security expertise with operational technology knowledge. These teams develop solutions that protect critical systems without compromising operational requirements.

Governance and Standards for OT Security

Several standards and frameworks can guide OT security efforts:

• IEC 62443 provides a comprehensive framework for industrial automation and control systems security
• NIST Special Publication 800-82 offers guidance on industrial control systems security
• NERC CIP standards cover critical infrastructure protection for the energy sector
• ISA/IEC 62443 addresses security for industrial automation and control systems

These frameworks provide valuable structure, but must be adapted to each organization’s specific operational requirements.

Board-Level Considerations

For executives and board members, OT security requires a different approach to governance:

• Risk assessments must include operational and physical impacts, not just data breaches
• Security investments should be evaluated against both security benefits and operational requirements
• Tabletop exercises should include scenarios that impact physical operations
• Business continuity and disaster recovery plans must address OT-specific scenarios
• Insurance coverage should be reviewed to ensure it addresses physical impacts of cyber events

The board should ensure that OT security receives appropriate attention and resources, recognizing that these systems often represent some of the organization’s most critical assets.

Looking Ahead: Emerging Challenges

Several trends are reshaping the OT security landscape:

1. The Industrial Internet of Things (IIoT)

The proliferation of connected sensors and devices in industrial environments creates new opportunities for monitoring and optimization, but also expands the attack surface exponentially. These devices often lack robust security features and may connect to cloud services, creating new pathways for attacks.

2. Edge Computing

Processing data closer to operational systems can improve performance and reduce latency, but also distributes computing resources in ways that complicate security monitoring and management.

3. AI and Autonomous Systems

As operational systems incorporate more artificial intelligence and autonomous decision-making, new security challenges emerge around algorithm integrity and the potential for adversarial attacks that manipulate these systems.

4. Regulatory Evolution

Regulations around critical infrastructure protection continue to evolve, with new requirements emerging at both national and international levels. Organizations must stay ahead of these changes to maintain compliance and security.

Conclusion: Security as an Operational Imperative

Operational technology security is not merely a technical concern—it’s a business imperative that directly impacts operational resilience, safety, and organizational sustainability. As physical and digital systems become increasingly interconnected, securing OT infrastructure requires specialized approaches that balance security requirements with operational needs.

The most successful organizations recognize that OT security isn’t just about protecting systems; it’s about ensuring operational continuity, maintaining safety, and enabling the digital transformation of physical processes. By bringing together IT security expertise with operational knowledge, organizations can develop security strategies that protect their most critical assets without compromising the operational requirements that make their business run.

As we continue to connect our physical infrastructure to digital networks, the security of these systems will only grow in importance. The organizations that thrive will be those that develop integrated approaches to securing both their information and their operations, recognizing that in today’s connected world, these are increasingly one and the same.

Tom Glover is Chief Revenue Officer at Responsive Technology Partners, specializing in cybersecurity and risk management. With over 35 years of experience helping organizations navigate the complex intersection of technology and risk, Tom provides practical insights for business leaders facing today’s security challenges.