implementing-iec-62443-security-zones

name	implementing-iec-62443-security-zones
description	Use when this skill covers designing and implementing security zones and conduits for industrial automation and control systems (IACS) per IEC 62443-3-2. It addresses zone partitioning based on risk assessment, assigning Security Level targets (SL-T), designing conduit security controls, implementing microsegmentation with industrial firewalls, and validating zone architecture through traffic analysis and penetration testing against the Purdue Reference Model.
domain	cybersecurity
tags	["ot-security","ics","scada","industrial-control","iec62443","network-segmentation","zones-conduits"]
subdomain	ot-ics-security
version	1.0.0
author	oyi77
license	Apache-2.0
nist_csf	["PR.IR-01","DE.CM-01","ID.AM-05","GV.OC-02"]

Implementing Iec 62443 Security Zones

Overview

Cybersecurity skill for implementing iec 62443 security zones. Follows industry best practices and security standards.

When to Use

Trigger phrases:

• "implementing iec 62443 security zones"

• "This skill covers designing and implementing security zones and conduits for ind"

• When designing a greenfield OT network architecture for a new industrial facility

• When retrofitting security zones into an existing flat OT network after an assessment finding

• When implementing network segmentation to comply with IEC 62443-3-2 certification requirements

• When upgrading from basic VLAN segmentation to policy-enforced zone/conduit architecture

• When an IT/OT convergence project requires defining security boundaries between enterprise and operational networks

Do not use for IT-only network segmentation (see implementing-network-microsegmentation), for cloud-native workload segmentation (see securing-kubernetes-on-cloud), or for physical security zone design without a cyber component.

When NOT to Use

• When you lack proper authorization for testing
• For production systems without change management
• When the task requires legal or compliance expertise beyond technical scope

Prerequisites

• Completed OT network security assessment with asset inventory and traffic flow analysis
• Understanding of IEC 62443-3-2 zone/conduit design process and the Purdue Reference Model
• Industrial firewalls capable of deep packet inspection for OT protocols (Palo Alto with OT Security, Fortinet OT, Cisco ISA-3000)
• Network switches supporting VLANs, 802.1Q trunking, and port security
• Approval from operations management for network architecture changes during maintenance windows

Workflow

# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": r"\b[a-z0-9-]+\.[a-z]{2,}\b",
    "hash_md5": r"\b[a-f0-9]{32}\b",
    "hash_sha256": r"\b[a-f0-9]{64}\b",
}

 () -> :
     {k: re.findall(v, text)  k, v  IOC_PATTERNS.items()}