BMS Controller Segmentation

Overview

Building Management Systems (BMS) include critical infrastructure that requires network isolation:

  • HVAC controllers

  • Lighting controls

  • Access control systems

  • Fire and safety systems

  • Energy management

  • Elevator controls

Security Concerns

  • Legacy protocols without authentication

  • Unpatched firmware

  • Default credentials

  • Flat network access to IT systems

Segmentation Strategy

┌─────────────────────────────────────────────────────────────┐
│                         Network                              │
├─────────────────────────────────────────────────────────────┤
│                                                              │
│  ┌──────────────┐    ┌──────────────┐    ┌──────────────┐   │
│  │  IT Network  │    │  BMS Network │    │  IoT Network │   │
│  │  VLAN 10     │    │  VLAN 100    │    │  VLAN 200    │   │
│  └──────┬───────┘    └──────┬───────┘    └──────┬───────┘   │
│         │                   │                   │            │
│         │     ┌─────────────┴─────────────┐     │            │
│         │     │         Firewall          │     │            │
│         │     │    (Inter-VLAN ACLs)      │     │            │
│         │     └───────────────────────────┘     │            │
│         │                   │                   │            │
│  ┌──────▼───────┐    ┌──────▼───────┐    ┌──────▼───────┐   │
│  │ Workstations │    │   BMS Mgmt   │    │  Supervisors │   │
│  │              │    │   Station    │    │              │   │
│  └──────────────┘    └──────────────┘    └──────────────┘   │
└─────────────────────────────────────────────────────────────┘

Implementation Phases

  1. Discovery - Profile all BMS devices

  2. Classification - Create endpoint identity groups

  3. Policy - Build authorization rules

  4. Enforcement - Apply DACLs/SGTs

  5. Monitoring - Verify traffic patterns