As industrial operations become more digitised and connected, cyber threats targeting Operational Technology (OT) systems are escalating.
However, traditional IT security measures fall short in safeguarding physical assets like programmable logic controllers (PLCs), human-machine interfaces (HMIs), and industrial sensors.
That’s why organisations must adopt OT security best practices specifically tailored to the unique risks and architectures of OT environments.
Understanding the OT vs IT Security Gap
Operational Technology (OT) and Information Technology (IT) operate under different objectives, architectures, and risk models.
IT security focuses on protecting digital assets such as data confidentiality, integrity, and availability (CIA).
OT security focuses on safeguarding physical processes, ensuring human and environmental safety, and maintaining continuous equipment uptime.
Architecture
IT systems are built on standardised, upgradable platforms using well-supported protocols like TCP/IP. However, OT systems often run on legacy infrastructure and proprietary protocols such as Modbus, Profibus, or DNP3.
These systems were not designed with security in mind. They often lack basic features like authentication, encryption, or logging. This makes them vastly different from modern IT networks both in terms of visibility and controllability.
Operational Priorities
In IT, downtime can often be scheduled and managed to apply patches or perform system upgrades. In contrast, OT environments prioritise uninterrupted operation. Even minimal latency or downtime can disrupt critical processes, halt production, or endanger safety systems.
This makes applying IT-style security tools and practices to
protect industrial systems and OT environments both impractical and potentially hazardous.
Risk Tolerance
IT systems tolerate some level of disruption in exchange for improved protection. But in OT, the cost of failure goes beyond data loss. It can cause physical destruction, environmental damage, or even loss of human life.
This stark contrast means that risk assessments, threat modelling, and incident response plans in OT must account for physical consequences and safety implications, not just business or reputational damage as in IT.
Understanding these
OT vs IT differences is key to shaping effective, non-disruptive, and resilient OT cybersecurity strategies. Every OT security control must be designed with these differences in mind.
Best Practice #1: Asset Inventory and Visibility
You can't secure what you don't know exists. A real-time, centralised asset inventory is foundational for any Operational Technology security program. Here’s how to put your asset inventory together.
- Identify every connected device, including PLCs, sensors, RTUs, HMIs, switches, and legacy systems. Many of these operate silently on industrial protocols.
- Use passive network discovery and deep packet inspection to map assets without interrupting sensitive industrial processes.
- Correlate device data with known vulnerabilities (CVEs) and link it to your incident response playbook for faster triage.
This level of visibility allows for proactive OT risk management. It is also essential for complying with frameworks like ISA/IEC 62443 and NIST CSF.
Best Practice #2: Network Segmentation and Zone-Based Architecture
Traditional flat OT networks allow attackers to move laterally once inside. One of the most impactful OT security best practices is implementing OT network segmentation, which contains threats and minimises damage.
Here’s how to implement OT network segmentation:
- Create zones and conduits as per IEC 62443 to isolate critical assets (e.g., safety systems, engineering workstations).
- Deploy demilitarised zones (DMZs) to safely bridge communication between IT and OT networks without exposing OT systems to internet-facing threats.
- Apply firewalls, VLANs, and access control lists (ACLs) to regulate traffic and enforce least-privilege communication pathways.
Proper segmentation ensures that even if an attacker breaches a single device, they cannot access the entire OT environment.
Best Practice #3: Secure Remote Access Management
Remote connectivity is often a necessity in OT for maintenance, updates, or vendor support, but it’s also a prime target for threat actors.
Here’s how to secure remote access:
- Use multi-factor authentication (MFA) to validate users beyond passwords.
- Route access through jump servers, where every session is authenticated, monitored, and terminated after use.
- Enforce session logging and screen recording to enable forensic review and detect policy violations.
- Restrict remote access to only what’s necessary.
- Disable unused ports/services.
- Apply just-in-time access controls to reduce persistent vulnerabilities.
Best Practice #4: Patch Management and Virtual Patching
Live patching is risky in OT environments due to potential disruption of functioning. That’s why
patch management in OT must be strategic and layered.
Here are the key steps to ensure strategic patch management:
- Develop a risk-based patching policy that considers asset criticality, vendor support timelines, and known threats.
- Use virtual patching via host-based intrusion prevention systems (HIPS) or next-gen firewalls to mitigate vulnerabilities when patching isn’t possible.
- Prioritise updates based on Common Vulnerability Scoring System (CVSS) scores and asset exposure.
Always vet patching decisions through impact assessments and include rollback procedures in case of failure.
Best Practice #5: OT-Specific Threat Detection and Monitoring
IT security tools often fail in OT environments because they lack awareness of industrial protocols and behaviours.
Here’s how to ensure effective OT threat detection:
- Deploy industrial intrusion detection systems (IDS) that recognise OT-specific anomalies (e.g., unusual PLC commands or abnormal I/O patterns).
- Focus on anomaly-based detection, as signature-based models may not account for the custom or legacy nature of many OT systems.
- Integrate detection data into your Security Information and Event Management (SIEM) platform for centralized correlation and response.
Visibility into OT network activity is essential for early warning and rapidly containing threats.
Best Practice #6: Incident Response and Tabletop Exercises
Without a tailored OT
incident response plan, even a minor breach can escalate into a crisis.
Here’s how you can strengthen your response posture:
- Create OT-specific IR playbooks that include roles for plant managers, system integrators, and safety personnel.
- Run regular tabletop exercises with realistic OT scenarios (e.g., ransomware on HMI, unauthorized PLC reprogramming).
- Ensuring joint response coordination between IT and OT teams, with clear communication channels and escalation paths.
These drills expose gaps, clarify responsibilities, and improve readiness for real-world incidents.
Best Practice #7: Employee Training and Access Controls
Insider threats and human error are leading causes of OT incidents. One of the most overlooked OT cybersecurity best practices is ongoing training and proper access management.
Ensure that you follow these steps:
- Conduct tailored training programs for engineers, operators, and maintenance personnel. Ensure the training covers OT-specific threats like USB attacks, credential misuse, or unauthorised reconfiguration.
- Enforce role-based access control (RBAC) so users can only perform tasks essential to their roles.
- Regularly review user access rights, especially after organisational changes or project completion.
A cyber-aware workforce dramatically reduces the likelihood of unintentional exposure.
Best Practice #8: Regulatory Compliance Alignment
Regulatory compliance does not just help with audits; it helps reduce OT cyber risk.
Here's how to align with regulatory requirements:
- Map your OT controls to frameworks like ISA/IEC 62443, NIST CSF, NESA (UAE), or NCA ECC (KSA) depending on your jurisdiction.
- Maintain detailed evidence of control implementation, including logs, network maps, and access control policies.
- Use compliance milestones as checkpoints for continuous improvement, not just one-time goals.
Staying compliant ensures not only regulatory safety but also operational integrity.
The complexity of OT systems, coupled with their real-world impact, demands a distinct security approach. Implementing these eight OT security best practices can help your organisation stay ahead of adversaries, prevent costly downtime, and safeguard both their people and processes.
Talk to our experts today
Thank you. An expert will get in touch shortly 
