🎓 Lesson 6
D4
Zoning Strategies for Open Pit vs. Underground Networks
Zoning strategies divide mine networks into secure, isolated segments—like putting firewalls between different parts of an open pit or underground mine—to stop cyberattacks from spreading.
🎯 Learning Objectives
- ✓ Analyze network topology to classify assets into appropriate security zones (e.g., Level 0–3 per ISA/IEC 62443)
- ✓ Design zone boundaries for an open-pit haul truck fleet using segregation principles and blast zone proximity constraints
- ✓ Explain how underground ventilation SCADA systems require stricter zone segmentation than surface crushing plants due to life-safety dependencies
- ✓ Apply ISA/IEC 62443-3-3 zone/conduit modeling to calculate minimum required security level (SL-T) for a given mine subsystem
📖 Why This Matters
A single compromised PLC in an underground conveyor belt once caused cascading failures across ventilation, dewatering, and hoisting systems—leading to a 17-hour emergency evacuation. Unlike IT networks, mine OT networks control physical processes where delays, misconfigurations, or lateral movement can trigger safety incidents, production loss, or regulatory penalties. Zoning isn’t about convenience—it’s the foundational defense that contains threats before they reach life-critical systems.
📘 Core Principles
Zoning follows the ISA/IEC 62443 ‘zone and conduit’ model: zones group assets with similar security requirements (e.g., identical risk tolerance, data sensitivity, and functional interdependence), while conduits define authorized communication paths between zones. Open-pit networks typically use geographic and functional zoning—e.g., drill fleet (Zone A), blast initiation network (Zone B), and dispatch system (Zone C)—with hardened conduits via encrypted radio links or fiber. Underground networks add depth-based zoning: shaft control (Zone 1), development headings (Zone 2), and production stopes (Zone 3), where each deeper zone demands higher assurance due to reduced redundancy and evacuation complexity. Criticality, latency tolerance, and legacy protocol support (e.g., Modbus RTU over RS-485) further constrain zone design.
📐 Zone Security Level Assignment
The required Security Level Target (SL-T) for a zone is derived from its Consequence, Likelihood, and Tolerance ratings per ISA/IEC 62443-3-3 Annex F. SL-T determines encryption strength, authentication rigor, and audit frequency.
💡 Worked Example
Problem: A primary underground ventilation SCADA zone has Consequence = 4 (catastrophic injury risk), Likelihood = 3 (probable due to unpatched HMIs), and Tolerance = 2 (low organizational risk appetite). Calculate SL-T.
1.
Step 1: Use ISA/IEC 62443-3-3 Table F.1 — map Consequence (4), Likelihood (3), and Tolerance (2) to base SL.
2.
Step 2: Apply adjustment factor +1 for life-safety dependency (per IEC 62443-3-3 §F.4.2).
3.
Step 3: Confirm final SL-T ≥ SL-C (Security Level Capability) of all devices in the zone.
Answer:
Base SL = 3; adjusted SL-T = 4. All controllers, HMIs, and sensors in this zone must support SL-C 4 (e.g., TLS 1.2+, role-based access control, 90-day audit logs).
🏗️ Real-World Application
At Newmont’s Boddington Mine (WA), open-pit zoning segmented GPS-guided drills (Zone 1), wireless blast initiation network (Zone 2), and centralized fleet management (Zone 3). Zone 2 was air-gapped from Zone 3 except via a single unidirectional optical conduit—preventing malware from fleet software from reaching detonation circuits. In contrast, at Vale’s Onça Puma underground operation (Brazil), ventilation zones were split by elevation: main fan control (Zone 1, SL-T 4) and local stope fans (Zone 2, SL-T 3), with conduit filtering limited to airflow setpoint commands only—blocking firmware updates or diagnostics traffic from upstream zones.
🔧 Interactive Calculator
🔧 Open Mine Automation Cybersecurity Framework Calculator📋 Case Connection
📋 Autonomous Haulage System (AHS) Cybersecurity Upgrade – Iron Ore Mine, Pilbara
Legacy CAN bus interfaces exposed to lateral movement; lack of secure firmware update mechanism
📋 Ventilation DCS Cyber Isolation – Underground Gold Mine, Ontario
Direct Ethernet connectivity between DCS and corporate IT network; no segmentation or protocol whitelisting
📋 IIoT Sensor Network Security for Tailings Monitoring – Copper Mine, Chile
Use of consumer-grade LoRaWAN gateways with default credentials; no sensor identity attestation