What is Security Monitoring?
Security Monitoring is the continuous observation, recording, and analysis of activities and events on a network or system in order to detect anomalies, threats, or incidents at an early stage.
In OT environments, Security Monitoring is essential to spot cyber attacks, misconfigurations, and unauthorised access before they disrupt production or safety.
🧠 How does Security Monitoring work?
- Data is collected from:
- The data is analysed centrally for:
- Unusual patterns (e.g. logins outside working hours)
- Known threats (signatures, MITRE ATT&CK techniques)
- Anomalies (machine learning, deviating behaviour)
- Alerts are generated for suspicious activity
- Analysts in a SOC (Security Operations Center) assess and respond
- Integration with SOAR or response playbooks enables automated handling
Security monitoring lays the foundation for Incident Response, Threat Hunting, and Forensics.
🏭 Application of Security Monitoring in industrial networks
- Detection of unwanted access to PLC, HMI, or Engineering Station
- Real-time logging of changes to process parameters or network configuration
- Monitoring of communication protocols such as Modbus TCP, OPC UA, GOOSE
- Collecting logs and flows in OT zones without impacting production
- Use of OT-specific analysis tools such as Nozomi, Claroty, Tenable.ot, etc.
Security monitoring must be tailored to OT-specific requirements such as availability, determinism, and network load.
🔍 IT vs. OT Security Monitoring
| Aspect | IT environment | OT environment |
|---|---|---|
| Priority | Availability + confidentiality | Availability + integrity |
| Monitoring tools | SIEM, EDR, SOAR | OT-aware SIEM, DPI tools, passive network sensors |
| Access control | Active Directory, Entra ID | Segmentation, RBAC, physical access |
| Update policy | Regular patches | Strictly controlled, often limited |
🔐 Security aspects
- Segmentation via VLAN, Firewall, and DMZ limits the spread of threats
- Combine with MITRE ATT&CK for ICS and MITRE D3FEND for structured detection
- Integrate log sources from both IT and OT for full visibility
- Apply Least Privilege to accounts and monitoring access
- Carry out regular tests via Pentest or Threat Simulations
An effective monitoring policy prevents blind spots and accelerates the detection of attacks or sabotage.
📌 In summary
Security Monitoring is indispensable for safeguarding OT networks, detecting threats early, and supporting incident response. Only with continuous, context-aware Monitoring can you safely manage modern industrial environments.