The OT security time bomb: Why legacy industrial systems are the biggest cyber risk nobody wants to fix

Legacy operational technology (OT) systems running on unpatched Windows XP, unauthenticated protocols like Modbus, and poorly segmented IT-OT networks represent a growing cybersecurity crisis in energy and pharma sectors. Three core blockers prevent action: downtime aversion, cultural gaps between IT and OT teams, and diffuse budget responsibility. Modern attackers exploit this by entering via IT networks and moving laterally into OT environments, as seen in Colonial Pipeline and Triton incidents. A practical remediation approach involves risk-based asset inventory, network segmentation per IEC 62443, OT-specific monitoring integrated into a SOC, using regulatory mandates as business case leverage, and stepwise modernization with compensating controls for systems that can't be replaced immediately.