What is an Insider Threat?
An Insider Threat is a security risk originating from people within the organisation — such as employees, suppliers or contractors — who, intentionally or unintentionally, cause harm to systems, processes or data.
In OT environments, insider threats are particularly risky because insiders often have access to critical systems such as PLC, SCADA, HMI or Engineering Station.
🧠 How does an Insider Threat work?
Insider threats typically arise from two scenarios:
- Malicious threats
- Sabotage of installations
- Theft of intellectual property
- Uploading malware or modifying control logic
- Negligent threats
- Unintended use of an infected USB stick
- Poor password practice
- Accidentally running the wrong software or code
Recognisable behaviours:
- Access outside working hours
- Attempted privilege escalation
- Configuration changes without a change request
- Connection to unauthorised devices or networks
🏭 Insider Threats in industrial networks
- An engineer modifies PLC code without documentation
- An operator bypasses safety interlocks via an HMI
- A maintenance technician installs their own software on an Engineering Station
- A former employee retains access to remote VPN or Jump Server
- A temporary contractor with overly broad permissions on the SCADA system
In OT, insider threats are often harder to detect, because the behaviour appears legitimate.
🔍 Insider Threat vs. Outside Threat
| Feature | Insider Threat | Outside Threat |
|---|---|---|
| Origin | Internal (employee, contractor, supplier) | External (hacker, cybercriminal) |
| Access | Often has legitimate access | Has to obtain access |
| Detection | Harder due to familiar behaviour | Often anomalous behaviour |
| Impact | High – direct access to OT systems | Varies, depending on penetration |
🔐 Security measures
- Least Privilege – minimal access rights
- RBAC – segregation of duties by role
- Logging & anomaly detection – monitor anomalous behaviour
- MFA and 802.1X – strong authentication
- Group Policy and endpoint Hardening
- Regularly remove accounts of former employees
- Security Awareness and training for OT personnel
- Grant temporary access via a controlled Jump Server or Remote Access
Insider threats require a combination of technical, organisational and behavioural controls.
📌 In summary
An Insider Threat is a real and underestimated risk in industrial environments. By bringing people, processes and technology together, this threat can be managed and damage limited.