detecting-dnp3-protocol-anomalies

name	detecting-dnp3-protocol-anomalies
description	Detect anomalies in DNP3 (Distributed Network Protocol 3) communications used in SCADA systems by monitoring for unauthorized control commands, firmware update attempts, protocol violations, and deviations from baseline traffic patterns using deep packet inspection and machine learning approaches. . Use when working with detecting dnp3 protocol anomalies.
domain	cybersecurity
tags	["ot-security","ics","dnp3","scada","anomaly-detection","protocol-analysis","energy-sector","ids"]
subdomain	ot-ics-security
version	1.0
author	oyi77
license	Apache-2.0
atlas_techniques	["AML.T0043","AML.T0018"]
nist_ai_rmf	["MEASURE-2.7","MEASURE-2.5","MAP-5.1"]
nist_csf	["PR.IR-01","DE.CM-01","ID.AM-05","GV.OC-02"]

Detecting Dnp3 Protocol Anomalies

Overview

Cybersecurity skill for detecting dnp3 protocol anomalies. Follows industry best practices and security standards.

When to Use

Trigger phrases:

• "detecting dnp3 protocol anomalies"

• "Detect anomalies in DNP3 (Distributed Network Protocol 3) communications used in"

• When monitoring SCADA systems in the energy sector where DNP3 is the primary protocol

• When building detection rules for DNP3-based attacks against RTUs and substations

• When investigating suspected unauthorized control commands sent via DNP3

• When deploying IDS with DNP3 deep packet inspection at utility substations

• When responding to alerts from OT monitoring platforms about DNP3 traffic anomalies

Do not use for non-DNP3 protocol monitoring (see detecting-modbus-command-injection-attacks for Modbus), for DNP3 Secure Authentication configuration (separate implementation), or for protocol-agnostic network anomaly detection.

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

• Network TAP/SPAN on DNP3 communication segments (TCP port 20000 or serial)
• Baseline of normal DNP3 traffic patterns (masters, outstations, poll intervals, function codes)
• Suricata or Zeek with DNP3 protocol parser enabled
• Understanding of DNP3 function codes and object groups used in the environment
• DNP3 communication topology map (master-to-outstation relationships)

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",
}

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