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Port 4024 – DNP3 (DNP3 Protocol)

Service:

dnp3

Protocol:

TCP

Port:

4024

Used for:

Distributed Network Protocol for SCADA systems

Why It’s Open

Port 4024 is used for DNP3 (Distributed Network Protocol), a specialized communication protocol designed for SCADA (Supervisory Control and Data Acquisition) systems in industrial environments. DNP3 over TCP enables reliable communication between control centers and remote terminal units (RTUs), intelligent electronic devices (IEDs), and other automation controllers in critical infrastructure sectors. Organizations deploy this protocol for real-time monitoring and control of power grid components, water treatment facilities, oil and gas pipelines, and other industrial processes. DNP3 is particularly valued for its robustness in challenging environments, support for time-synchronized data, and efficient bandwidth utilization, making it essential for operational technology networks that require deterministic communication for critical infrastructure operations.

Common Risks

  • Unauthorized access
    Weak or default credentials may allow intrusion
  • Service vulnerabilities
    Unpatched software may contain security flaws
  • Information disclosure
    Service may leak sensitive system information
  • Resource exhaustion
    Service abuse can impact system performance
  • Protocol attacks
    Specific TCP protocol vulnerabilities

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Enumeration & Testing

Service Detection:

Terminal window
nmap -sV -p 4024
Terminal window
nc  4024

Vulnerability Scan:

Terminal window
nmap --script vuln -p 4024

What to Look For

CheckpointWhat it means
Service versionIdentify software version and patch level
AuthenticationCheck for default or weak credentials
SSL/TLS configVerify encryption settings if applicable
Access controlsTest for proper authorization mechanisms

Mitigation

  • Keep SCADA systems updated
    Apply security patches after proper testing
  • Implement defense in depth
    Use multiple security layers to protect critical systems
  • Network segmentation
    Isolate industrial control networks from IT networks
  • Secure DNP3 authentication
    Enable and properly configure authentication features
  • Encryption for sensitive data
    Use TLS tunneling or VPNs when possible
  • Intrusion detection systems
    Deploy ICS-specific monitoring solutions
  • Regular security assessments
    Conduct specialized SCADA security audits
  • Physical access controls
    Restrict access to SCADA equipment and networks

Real World Example

In 2015, researchers identified vulnerabilities in multiple DNP3 protocol implementations that could allow attackers to execute denial-of-service attacks against power grid and water system controllers. The flaws affected devices using the DNP3 protocol on port 4024, and could allow attackers to crash master stations by sending specially crafted messages. This highlighted the critical importance of industrial protocol security as these systems control essential infrastructure components across multiple sectors including energy, water, and manufacturing facilities.

TL;DR

  • Port 4024 = DNP3 Protocol service
  • Protocol: TCP
  • Used for: Distributed Network Protocol for SCADA systems
  • Security focus: Proper configuration and monitoring required

Known CVEs and Exploits

  • CVE-2018-7522 – DNP3 protocol stack buffer overflow vulnerability in multiple implementations
  • CVE-2019-6568 – SCADA/ICS systems DNP3 authentication bypass vulnerability
  • DNP3 protocol weaknesses – Lack of encryption and authentication in legacy implementations
  • SCADA-specific attacks – Industrial control system manipulation and unauthorized command injection