Operational Technology (OT) cybersecurity is often treated as a specialized domain owned by IT security teams or compliance functions. In practice, the effectiveness of OT Cybersecurity for Engineers depends far more on engineering decisions made at the system level.
Control systems are not passive digital assets; they are active environments that monitor and control physical processes. As a result, cybersecurity failures in OT environments directly translate into operational disruption, equipment damage, and safety risks.
For this reason, cybersecurity in OT is not a separate function. It is an extension of engineering discipline, system design, and operational accountability.
In the recent OT Cybersecurity webinar, “OT Cybersecurity for Engineers,” Navid Razzaq, Technical Leadership Manager at ACET Solutions and practitioner with over 20 years of experience in IT/OT infrastructure and industrial cybersecurity, framed the session’s core argument:
“Security is not separate from engineering. It is an extension of it.”
Watch the full webinar here.
The Convergence of Control Engineering and Cybersecurity
Control systems in real-time operational environments are designed to automate industrial processes. Their structure reflects functional roles across multiple layers:
- Field devices – Sensors and actuators interacting with physical processes
- Controllers (PLCs/DCS/RTUs) – Executing control logic
- HMI/SCADA systems – Supervisory control and operator interface
- Control networks – Enabling communication across all layers
These communications often rely on industrial protocols such as Modbus, DNP3, and OPC UA, many of which were not originally designed with security in mind.
As a result, they do not have native authentication and encryption, and thus are vulnerable to spoofing, replaying attacks, and unauthorized command injections unless they are appropriately segmented and monitored.
Historically, these systems were designed to be reliable and have high up time, with the goal to stay stable. Over time with the increase in connectivity, the focus of the engineers remains on the operation’s continuity while the threats of cybersecurity grew.
The disconnect between design and expanded exposure to threats is where the cultural gap between engineering and cybersecurity originates.
The OT Culture Gap: Stability vs Security
A fundamental difference exists between engineering and cybersecurity perspectives:
|
Control Engineers |
Cybersecurity Teams |
|
Prioritize system stability and uptime |
Prioritize risk reduction and threat mitigation |
|
Avoid changes if systems are running |
Treat connected systems as exposed |
|
Focus on operational continuity |
Focus on minimizing attack surface |
This divergence creates friction in real-world environments.
Operational reality:
Security controls that introduce latency, downtime, or instability are often resisted, even if they reduce risk.
Required evolution:
Modern industrial environments demand a hybrid skillset:
- Control system expertise
- IT and network integration knowledge
- Cybersecurity awareness aligned with operational impact
Bridging this gap is essential. Without it, organizations remain vulnerable, not due to lack of tools, due to misaligned priorities.
A Four-Pillar Framework for OT Cybersecurity
Effective OT cybersecurity must align with engineering principles: structured, repeatable, and grounded in operational realities.
This can be achieved through four core pillars:
- Secure Design & Architecture
- Operational Discipline and Habits
- Incident Preparedness and Detection
- Risk Communication and Mindset
Each pillar integrates cybersecurity into engineering workflows rather than treating it as an external control function.
These pillars align closely with globally recognized frameworks such as IEC 62443 and NIST SP 800-82, which define security requirements for industrial automation and control systems across architecture, operations, and risk management.
Integrating these standards into engineering workflows ensures that cybersecurity controls are not only technically sound but also operationally viable within industrial environments.
-
Secure Design & Architecture: Building Security into the System
Segmentation as a Control Mechanism for Risk Containment
Network segmentation divides systems into controlled zones to limit the spread of malware, unauthorized access, or malicious commands
In OT environments, segmentation is not just a best practice, it is a primary safety mechanism.
From an architectural standpoint, effective segmentation in OT environments should follow a zone and conduit model, where systems with similar security requirements are grouped into zones, and communication between them is strictly controlled through defined conduits.
This approach enforces deterministic traffic flows, minimizes lateral movement, and allows engineers to apply granular security policies such as protocol whitelisting and deep packet inspection for industrial protocols.
Example:
A malware infection in a non-critical network should not spread to control systems of high-risk industrial processes.
In reality, the failure of segmentation initiatives is not necessarily related to technical constraints, but operational teams are not able to absorb interruptions to the current streams of communication. This results in excessive permissive settings that weaken security.
Demilitarized Zones (DMZ) as Controlled Boundaries
A DMZ acts as an intermediary layer between IT and OT systems.
Its purpose is to:
- Prevent direct communication between enterprise and control networks
- Enable controlled data exchange
- Limit attack propagation across domains
Without a properly implemented DMZ, an initial compromise in the IT network can move laterally into OT systems, allowing attackers to access control networks, manipulate industrial processes, and potentially disrupt operations or create unsafe conditions.
Secure-by-Design Systems, Not Vendor Dependency
Security must be embedded into system architecture, not delegated entirely to vendor features.
While secure capabilities (e.g., credential management, logging, and port control) are important, however, they are only effective when:
- Integrated into system design
- Properly configured
- Continuously enforced
Key principle:
A system is not secure because it has security features; it is secure because those features are architecturally enforced and operationally maintained.
Documentation as a Foundational Security Control
Accurate documentation is essential for maintaining system security and recoverability.
This includes:
- Asset inventories (devices, firmware, configurations)
- Network diagrams and communication flows
- Patch and change history
Why it matters:
Without documentation, organizations lack visibility, making it impossible to identify vulnerabilities, validate controls, or recover systems effectively after an incident.
-
Operational Discipline: Embedding Security into Daily Engineering Practice
Cybersecurity in OT is not periodic; it is continuous and behavior driven.
Change Management as a Security Control
All system changes must be:
- Documented
- Authorized
- Traceable
This ensures accountability and prevents both accidental misconfiguration and malicious changes.
Access Control and Accountability
Shared accounts eliminate traceability and increase risk.
Secure environments require:
- Individual user accounts
- Role-based access control
- Enforcement of least privilege
This ensures that users only have access to what is necessary, and actions can be attributed.
Media and External Access Control
Uncontrolled removable media introduces critical risks, including malware introduction into isolated control networks, unauthorized data exfiltration, and the execution of unverified or malicious software that can bypass network-based security controls.
Controls must include:
- Strict validation of external media
- Controlled usage policies
- Monitoring of data transfer points
Patch Management with Operational Awareness
Patching in OT environments must be carefully controlled:
- Tested in non-production environments
- Implemented with rollback capability
- Monitored after deployment
Critical risk:
In OT environments patching is not always feasible. Therefore. Bulk or unnecessary patching can disrupt control processes, leading to system instability or downtime.
-
Incident Preparedness: Engineers as the First Line of Detection
Control engineers have a unique advantage, they understand how systems should behave under normal conditions.
This allows early detection of anomalies such as:
- Unexpected communication delays
- Irregular process variable behavior
- Subtle performance degradation
Organizations that rely solely on IT-centric monitoring often detect incidents only after operational impact has occurred.
Backup and Recovery for Operational Continuity
Backups are only valuable if they can be used effectively.
A resilient strategy includes:
- Offline backups protected from ransomware
- Regular validation through restoration testing
- Clearly defined recovery procedures
Risk of failure:
Untested backups often fail during real incidents, extending downtime and increasing operational impact.
Crisis Response Drills for Industrial Environments
Incident response must be practiced, not improvised.
Regular drills help:
- Establish roles and responsibilities
- Enhance collaboration between IT and OT teams
- Shorten the response time in actual incidents
Without preparation, response efforts become reactive and ineffective.
-
Risk Communication: Translating Cyber Threats into Operational Impact
Technical vulnerabilities must be communicated in operational terms.
For example:
- “This PLC is vulnerable” → lacks urgency
- “This vulnerability can override safety interlocks” → defines real risk
Engineers play a key role in bridging communication between cybersecurity and operations.
They must also guide IT teams on:
- Safe maintenance windows
- Timing of updates and scans
- Operational constraints affecting security controls
Effective cybersecurity depends on aligning technical risk with operational consequences.
Key Technical Concepts in OT Cybersecurity
Purdue Model and Its Limitations
The Purdue Model defines hierarchical levels in industrial systems, from field devices to enterprise IT.
It helps structure segmentation and communication control.
Limitation:
Modern environments with cloud integration and remote access often bypass strict hierarchical boundaries, requiring more flexible security models.
Active Directory Separation Between IT and OT
Best practice requires separating IT and OT identity systems.
Why direct trust is dangerous:
- Compromise in IT can propagate into OT
- Expands attack surface across environments
- Breaks isolation between domains
Secure integration must be controlled through intermediary layers such as DMZs.
Antivirus Deployment Risks in OT Systems
Antivirus remains necessary but must be deployed carefully.
Risk of improper deployment:
- System performance degradation
- Interference with real-time processes
- Unexpected system crashes
Security controls must not compromise operational stability.
Passive Monitoring for Safe Visibility
Passive monitoring enables:
- Asset discovery
- Threat detection
- Network visibility
without actively interacting with systems.
This approach is critical in OT environments where active scanning can disrupt operations.
Emerging Risks from AI and Cloud Integration
AI and cloud technologies are increasing efficiency but also expanding exposure.
Impact:
- More entry points into OT environments
- Increased dependency on external systems
- Reduced control over data flow and processing
Organizations must balance innovation with architectural security controls.
Conclusion: Security as an Engineering Responsibility
OT cybersecurity is not an external layer applied to industrial systems. It is a direct extension of engineering responsibility.
Secure environments are built through:
- Structured architecture
- Disciplined operations
- Continuous monitoring
- Clear communication of risk
Organizations that treat cybersecurity as separate from engineering will struggle to maintain resilience as connectivity increases.
OT systems are not compromised because threats are unknown, they are compromised because security is not integrated into how systems are designed, operated, and maintained.
Security does not sit alongside engineering.
It is engineered.
Building secure OT environments requires aligning engineering practices with cybersecurity principles.
Explore how ACET Solutions supports organizations in designing and securing industrial systems that prioritize safety, reliability, and resilience.
Related Articles
