Operational Technology (OT) Cyber Security
Protecting industrial control systems through engineering-driven OT cyber security for critical infrastructure environments.
Operational Technology environments run the systems that keep society functioning.
Power generation, water systems, manufacturing, transport and defence infrastructure all rely on industrial control systems operating safely and continuously.
Traditional IT cyber security approaches often fail in these environments.
Calexi specialises in engineered OT cyber security for high-risk environments, helping organisations secure industrial networks without disrupting operations.
Our approach balances three realities:
- Security
- Operational continuity
- Budget and engineering constraints
The result is practical, resilient cyber security designed specifically for operational technology systems.
What Is Operational Technology (OT) Cyber Security?
Operational technology cyber security protects systems that monitor and control physical processes.
Operational technology cyber security is closely related to ICS cyber security, which focuses on protecting industrial control systems such as SCADA platforms, PLC controllers and distributed control systems.
These environments commonly include:
- SCADA platforms
- Distributed control systems (DCS)
- Programmable logic controllers (PLC)
- Remote terminal units (RTU)
- Intelligent electronic devices (IED)
- Industrial sensors and actuators
- Human-machine interfaces (HMI)
- Engineering workstations
Unlike traditional IT systems, OT networks often:
- run legacy equipment
- require high uptime & cannot be patched frequently
- operate safety-critical processes
This requires a specialised cyber security engineering approach.
Calexi provides industrial cyber security engineering for organisations operating critical infrastructure and industrial control environments.
OT Environments We Secure
Calexi provides cyber security engineering for operational environments across critical infrastructure sectors.
Typical environments include:
- Energy generation and distribution
- Water and utilities
- Defence and national security infrastructure
- Industrial manufacturing
- Transport and logistics systems
- Mining and resources
- Government operational facilities
Our Engineering-First OT Security Approach
Most cyber security firms approach OT environments using IT security tooling.
Calexi takes a different approach.
Operational technology systems control physical processes, critical infrastructure and industrial production. Security therefore must be designed with a clear understanding of how these systems operate, how failures occur, and how cyber events can affect real-world operations.
We apply systems engineering and cyber security engineering principles to design security controls that work within industrial environments without disrupting operational processes.
Our approach focuses on the following principles.
Operational awareness
Security controls must respect operational realities.
Industrial environments often require continuous uptime, strict safety constraints and tightly controlled change processes. Controls that work well in enterprise IT environments can cause disruption or instability in operational systems.
Calexi designs security controls that support production continuity, safety requirements and operational constraints.
Understanding Operational Failure Modes
Industrial control systems operate as interconnected processes where failures can propagate through multiple components.
Before implementing security controls, Calexi examines how systems behave under fault conditions and identifies failure modes within control systems, sensors, actuators and automation logic.
Understanding these failure modes helps ensure that security improvements do not introduce instability and that protection mechanisms align with how the system actually operates.
Cascading System Risk Modelling
Cyber incidents in OT environments rarely affect a single system in isolation.
Because industrial systems are tightly interconnected, failures can propagate through control systems and operational processes.
Calexi evaluates system dependencies, control system interactions and process automation flows to identify potential cascading impacts across industrial environments. This modelling helps organisations understand how cyber events could affect production systems, infrastructure services and safety-critical processes.
Industrial network architecture
Industrial networks form the backbone of operational environments.
Rather than relying solely on software tools, Calexi secures OT environments through industrial network architecture, segmentation and access control. This includes designing secure network zones, controlling communication pathways and improving visibility across industrial networks.
Many industrial environments follow architecture models such as the Purdue Enterprise Reference Architecture to separate operational systems from enterprise networks.
Calexi designs OT security architectures aligned with these principles and recognised industrial cyber security standards such as IEC 62443, supporting secure system boundaries, controlled data flows and improved visibility across industrial networks.
Engineering integration
Security is engineered into the system architecture rather than bolted on after deployment.
Calexi integrates cyber security controls directly into the design and operation of industrial systems, ensuring security improvements support long-term system stability and maintainability.
Risk-based implementation
Operational technology environments require targeted security improvements that meaningfully reduce risk.
Calexi focuses on implementing controls that address real operational risks, rather than applying generic compliance checklists or one-size-fits-all security solutions. This ensures security investments deliver practical improvements while respecting operational constraints.
OT Cyber Security Services
Calexi provides specialised OT cyber security services designed for industrial environments and critical infrastructure systems.
Our services focus on industrial cyber security engineering, helping organisations secure operational technology without disrupting production systems or operational processes.
OT Security Architecture and Design
We design secure OT architectures aligned to industrial environments and control system requirements.
Services include:
- Industrial network segmentation
- Secure zone and conduit architecture
- SCADA and ICS network architecture
- Secure remote access architecture
- Secure data transfer pathways
- IT/OT convergence security
- Architecture aligned with the Purdue model
Industrial Network Security
We secure the underlying network infrastructure that connects industrial control systems.
This includes improving visibility across industrial networks and restricting unnecessary communication between systems.
Services include:
- OT network mapping and asset discovery
- Industrial protocol analysis
- Industrial network segmentation design
- Firewall and industrial gateway policy design
- Secure remote operations access
- Monitoring for ICS cyber security threats
OT Risk Assessments
We conduct targeted assessments to understand the cyber risk exposure of operational technology environments.
These assessments focus on how cyber incidents could affect industrial systems and operational processes.
Services include:
- Industrial network exposure analysis
- System criticality assessment
- Operational impact analysis
- Safety and process integrity risks
- ICS cyber security attack pathways
This provides organisations with a clear engineering roadmap for improving industrial cyber security.
Critical Infrastructure Cyber Security
We help organisations protect nationally significant systems and essential services.
Our work supports organisations operating within regulated critical infrastructure environments.
Services include:
- Security of Critical Infrastructure Act (SOCI) alignment
- Australian cyber security frameworks
- Industrial cyber security standards
- Operational risk and resilience frameworks
- Critical infrastructure cyber risk assessments
OT Security Engineering Implementation
Where many consultancies stop at reports, Calexi implements engineered OT cyber security solutions.
Services include:
- Industrial network redesign
- Firewall architecture and segmentation implementation
- Industrial monitoring and detection engineering
- Identity and access control for OT systems
- Secure vendor and remote access
- Secure IT/OT system integration
Our focus is delivering practical industrial cyber security improvements that strengthen operational resilience without disrupting production systems.
OT Security Challenges We Solve
Operational environments face unique cyber security challenges.
Common issues we help solve include:
- Flat industrial networks with no segmentation
- Unsafe IT-OT integration
- Insecure remote vendor access
- Legacy industrial equipment
- Limited visibility into industrial networks
- Lack of cyber security engineering expertise
- Compliance pressure from regulators and customers
Calexi helps organisations address these risks without disrupting operations.
Proven Capability in the Field
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Ransomware Incident Response
When a ransomware attack exposed poor practices and failed backups, Calexi led the recovery, restored three months of data, implemented emergency fixes, and re-architected the ICT environment. The organisation avoided major reputational and financial loss while strengthening long-term resilience.
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Defence Capability Review
Calexi completed a Defence cyber capability review in just six weeks, engaging hundreds of stakeholders to provide clear visibility of the current state, align future technologies with strategy, and deliver actionable, risk-based recommendations with strong buy-in.
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Microsoft 365 Service Migration
A Defence SME struggling with multi-day outages migrated to Microsoft 365 under Calexi’s leadership. The seamless migration achieved zero downtime, 100% staff adoption, and significant resilience uplift, enabling faster collaboration and growth.
Why Organisations Choose Calexi
Calexi works with organisations operating high-risk infrastructure and sensitive environments.
What makes our approach different:
Engineering heritage
Our team includes systems engineers and cyber security engineers, not just compliance consultants.
Industrial realism
We understand the constraints of operational systems.
Security must support uptime and safety.
Critical infrastructure experience
We support organisations operating systems of national importance.
Practical security
We deliver security improvements that can actually be implemented in operational environments.
Frequently Asked Questions
Operational Technology (OT) cyber security protects the systems that monitor and control physical processes.
These environments include industrial control systems such as SCADA platforms, distributed control systems (DCS), programmable logic controllers (PLC), remote terminal units (RTU), intelligent electronic devices (IED), and operator workstations.
Unlike traditional IT systems, these technologies directly control industrial equipment, infrastructure and safety-critical processes. OT cyber security focuses on protecting these systems while maintaining operational continuity, safety and reliability.
Operational technology environments operate under very different constraints compared with corporate IT networks.
Key differences include:
- Many industrial systems run legacy operating systems or vendor-controlled platforms
- Downtime may disrupt physical processes or critical services
- Systems often require continuous operation for months or years
- Patching cycles may be limited or controlled by equipment vendors
- Safety considerations may override traditional IT security practices
As a result, OT cyber security requires specialised architecture, network design and risk management approaches rather than applying standard IT security controls.
Operational technology systems control infrastructure that society depends on, including electricity, water, transport, manufacturing and defence systems.
A cyber attack against these systems can lead to:
- operational shutdowns
- disruption of essential services
- safety incidents
- economic damage
- national security risks
For organisations operating critical infrastructure, OT cyber security is essential for maintaining resilience, safety and service continuity.
Many operational environments were designed before cyber threats became a major concern.
Common security challenges include:
- flat industrial networks with little segmentation
- insecure remote vendor access
- legacy systems that cannot be patched regularly
- poor visibility into industrial network traffic
- uncontrolled integration between IT and OT networks
- lack of specialised OT cyber security expertise
Addressing these risks requires a combination of engineering design, network architecture improvements and operational security controls.
Calexi provides specialised OT cyber security services designed for industrial and critical infrastructure environments.
Our capabilities include:
- OT security architecture and engineering
- industrial network segmentation and design
- secure IT-OT integration
- OT cyber risk assessments
- secure remote access architecture
- industrial monitoring and detection engineering
- cyber security engineering for critical infrastructure environments
We focus on delivering practical, engineered security improvements that support operational requirements.
Yes. Effective OT cyber security is designed to support operational requirements rather than interfere with them.
Security controls can often be implemented through:
- network segmentation
- improved access control
- architectural improvements
- monitoring and visibility
- controlled integration between IT and OT networks
A carefully engineered approach allows organisations to reduce cyber risk while maintaining uptime and safety requirements.
he first step is gaining a clear understanding of the operational technology environment and the risks associated with it.
In operational environments, cyber security must consider not only digital threats but also how failures propagate through physical systems.
A structured starting point typically includes:
- identifying critical operational systems and industrial assets
- mapping OT network architecture and system dependencies
- identifying failure modes within control systems and industrial processes
- assessing how cyber incidents or security mitigations could trigger cascading operational impacts
- evaluating safety, operational and service continuity risks
- prioritising architectural improvements and security controls
This approach allows organisations to move beyond generic cyber assessments and instead understand how cyber events could impact real-world operations.
Calexi works with organisations to develop engineering-driven OT security roadmaps that reduce cyber risk while maintaining operational stability and safety.
Secure Your Operational Technology Environment
Operational technology systems are increasingly targeted by cyber threats.
Protecting them requires specialised engineering expertise.
Calexi helps organisations secure industrial systems, critical infrastructure and operational environments through practical, engineered cyber security.