What is Supplier Security?
Supplier Security refers to managing the security risks arising from external suppliers, service providers, or partners. In OT (Operational Technology) environments, suppliers are often involved in delivering, maintaining, or managing systems such as PLC, SCADA, Remote Access, and software.
Supplier Security is essential because vulnerabilities at suppliers can directly affect the production, safety, and continuity of industrial installations.
🧠 Why is Supplier Security important?
- Suppliers may have access to sensitive OT systems
- External software or hardware may contain weaknesses
- Remote Access opens the door to potential cyber threats
- NIS2, IEC 62443, and ISO 27001 set requirements for supply chain security
🛡️ Important measures for Supplier Security
1. Contractual arrangements
- Include security requirements in contracts or SLAs
- Obligation to comply with standards such as IEC 62443-2-4 or ISO 27001
- Define responsibilities for incidents, audits, and notification duties
2. Access management
- Apply the Least Privilege principle
- Jump Server or Remote Access with MFA, logging, and time limits
- Use of 802.1X, RADIUS, and ACL
3. Supplier classification
- Map which suppliers have access to OT
- Determine risk profile based on role, level of access, and location (on-site vs. remote)
4. Audits and monitoring
- Assess supplier security via audit or questionnaires
- Monitor supplier activity in systems (SIEM, Security Monitoring)
5. Policy and procedures
- Part of the information security policy
- Clear access procedures and offboarding of supplier accounts
- Regularly update access rights and credentials
🏭 Example scenarios in OT
| Supplier type | Security risk | Mitigating measure |
|---|---|---|
| PLC supplier | Remote firmware upload with backdoor | Whitelisted access only via Jump Server |
| Maintenance technician | Physical access to network via laptop | Access via guest network + monitoring via SPAN |
| Software supplier | Unpatched HMI application | Patch management, Vulnerability Management |
| Cloud/SaaS service provider | Access to process data via API | Encryption, API token management, Audit logs |
🔐 Standards & regulations
- IEC 62443-2-4 – Requirements for integrators and service providers
- ISO 27001 / ISO 27036 – Supplier security
- NIS2 – Increased requirements for supply chain security
- BIO – Dutch government guideline with specific supply chain measures
📌 In summary
Supplier Security focuses on covering risks in the supply chain of OT environments. By means of technical, organisational, and contractual measures, external parties are controlled and risks are reduced.