Why remote access becomes the fastest path to impact
OT environments often depend on remote maintenance, OEM/vendor troubleshooting, and shared engineering tooling. Attackers target these pathways because they can bypass segmentation and inherit privileged access.
OT-safe mindset
Prioritize safety and uptime: start with visibility and approvals, then enforce only on the highest-risk paths first.
Minimum viable hardening (do this first)
- Just-in-time access: remote access enabled only during approved windows.
- Step-up verification for privileged actions or OT zone entry.
- Destination allow-list: restrict vendor sessions to specific assets/services.
- Session evidence: record approvals, policy decisions, and session metadata.
OT-safe rollout order
Observe → Warn → Enforce
Start with visibility. Alert on deviations. Enforce on the highest-risk paths first (IT-to-OT bridges, jump hosts, engineering stations).
Common misconfigurations
- Shared vendor accounts and static credentials
- Unrestricted VPN access across multiple zones
- Jump hosts that can reach everything
- No per-session approvals or audit trail
Recommendations
Vendor access
Use just-in-time approvals, enforce allow-listed destinations, and require step-up verification for zone entry.
Remote maintenance
Bind sessions to verified identity + device posture, and record evidence (who, what, when, where, why).
Segmentation
Model zones/conduits and stage enforcement to reduce blast radius without downtime.
Monitoring
Stream decision and session events to SIEM/SOAR; alert on drift and unusual access patterns.