Why vendors should validate themselves before the customer does

Vendor validation is often seen as something performed solely by the asset owner, operator, or integrator (with or without help of external companies). In practice, it can be just as valuable for vendors to apply the same approach to themselves prior delivering solutions to their customers. By doing so, vendors can review whether their terms and conditions are aligned with what they deliver, whether their internal practices are sufficiently formalized, and how ready they are for customer expectations related to IEC 62443-2-4. This also fits within a broader supply chain security approach, which is increasingly relevant in the context of NIS2. Secudea explicitly positions vendor validation and security testing in that wider supply-chain and NIS2 context.

Why validate at vendor side?

Vendor validation is often associated with customer due diligence, but it is also a strong internal improvement tool for suppliers. It helps vendors assess whether their contractual commitments, delivery practices, and cybersecurity controls are realistic, consistent, and defensible before customers start asking difficult questions. That matters because the vendor validation approach is built around defining cybersecurity requirements, checking supplier responses, technically validating solutions, and assessing residual risk before deployment.

Terms and conditions need to match reality

One of the most practical reasons for vendors to validate themselves is to review the terms and conditions they already use. Customers increasingly expect clarity on hardening, patching, remote access, support, testing, incident handling, and the treatment of residual risk. If those topics are not clearly reflected in a vendor’s contractual baseline, or if the commitments do not match actual delivery practices, friction is inevitable. Vendor-side validation helps close that gap by aligning contractual wording with real technical and operational capability. This makes the vendor’s position stronger and more credible.

Good practices are often already there

In many cases, vendors are not starting from zero. Their teams may already apply sensible cybersecurity practices during engineering and deployment, but often in an ad hoc way. The issue is therefore not always a lack of good practice, but more a lack of structure, consistency, and evidence. Existing habits need to be formalized into policies, procedures, templates, checklists, and records so they become repeatable and demonstrable. That is often the real step needed to mature toward supplier-oriented standards such as IEC 62443-2-4.

IEC 62443-2-4 readiness needs structure

Readiness toward IEC 62443-2-4 is not only about doing the right things technically. It is also about being able to show that cybersecurity requirements are handled in a structured and repeatable way. For many vendors, this means formalizing what they already do well and proving that it is applied consistently across projects. Policies and procedures matter, but so does follow-up: teams need to use them, deviations need to be tracked, and lessons learned need to improve future deployments.

FAT and SAT testing should be mandatory

This is also why security FAT and SAT testing should be mandatory during deployments. Simply specifying cybersecurity requirements is not enough, because the maturity and quality of the implemented solutions can vary significantly from supplier to supplier. The delivered solution must be technically validated to verify that what is written on paper is implemented in practice. FAT and SAT security testing helps confirm whether hardening measures are in place, whether configurations match the intended design, whether issues have been resolved, and what residual risk remains.

In-house or external testing

These tests can be performed in-house, and that can be a valid approach when the vendor has the right expertise and a mature methodology. But then strong documentation is essential: scope, procedures, evidence, findings, and follow-up actions all need to be clearly recorded. Testing can also be performed by an external party, which can add independence and credibility. In that case, proper scoping and strong follow-up are critical so that the testing is relevant, the findings are actionable, and the outcomes are linked back to real project decisions and risk management. The important thing however, is that the test outcome is not seen as an endpoint, but as a way and opportunity for continuous improvement.

Supply chain security and NIS2

Vendor-side validation is not only useful for contracts and project execution. It also strengthens a vendor’s position in the broader supply chain. Vendors that can demonstrate structured validation, documented practices, and repeatable FAT/SAT testing are better positioned to support customers who must take supply chain cybersecurity seriously under NIS2 expectations.

Conclusion

Vendor validation at the vendor side is about more than an assessment. It is about becoming easier to trust. Vendors that review their own terms and conditions, formalize the good practices they already have, improve their readiness toward IEC 62443-2-4, and make security FAT/SAT testing mandatory during deployments are in a much stronger position toward customers. They reduce ambiguity, improve consistency, and show that cybersecurity is built into delivery rather than added afterwards.

Want to strengthen your terms and conditions, formalize your cybersecurity practices, and improve your readiness toward IEC 62443-2-4? Contact us for more information about our Vendor Validation Services and Security FAT/SAT Testing approach.