IT vs OT Security
OT security is fundamentally different from IT. Priority is availability and safety—a security failure can result in physical damage, environmental harm, or loss of life.
OT Security Reality
- Availability first: Downtime = production loss, safety risk
- Legacy systems: 20+ year lifecycles, no patches
- Insecure protocols: Modbus, DNP3 lack authentication
Purdue Model Architecture
OT Network Levels
Level 4-5
Enterprise, business
Level 3
Site operations, DMZ
Level 1-2
Control, HMI, SCADA
Level 0
Physical process
Key Principle
Never allow direct IT-to-OT access. All traffic must traverse a DMZ with industrial firewalls, jump servers, and monitoring.
Implementation Roadmap
OT Security Program
Phase 1: Visibility (M 1-6)
Asset inventory, network mapping, risk assessment
Phase 2: Protection (M 7-12)
Network segmentation, access control, secure remote access
Phase 3: Detection (M 13-18)
OT monitoring deployment, anomaly detection, alerting
Phase 4: Optimization
Continuous improvement, threat intel, exercises
Security Controls
OT Security Framework
Network
Access
Monitoring
Response
Start Here
Asset inventory and network visibility first. You can't protect what you don't know exists. Many OT environments lack basic asset documentation.
Conclusion
OT/ICS security requires specialized approaches balancing security with availability and safety. Start with visibility, implement segmentation, and deploy OT-specific monitoring.
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Written by
Asfaleia Team
Security Consultant
OT security specialist with experience in critical infrastructure protection.