How do security teams decide whether APIs or remote services belong in CRA evidence?

When does an API or remote service become evidence under the CRA?

The product-function test is the practical line security teams use. If the API or remote service is part of how the product is meant to work, and the manufacturer designed, maintained, or materially depended on it, it belongs in the evidence story. The key question is not whether it is “behind the scenes”, but whether the product would lose intended functionality without it.

What counts as part of the product, not just a supporting integration?

Teams should treat APIs and remote services as in scope when they are required for core behaviour, delivery of features, or normal operation of the product. That includes backend processing, hosted lookups, update checks, device or user enrolment flows, and other remote steps that the product expects in production. A browser-only page is different from a product whose behaviour depends on remote calls.

For evidence purposes, the distinction is behavioural rather than architectural. If a customer-facing function, safety-related function, or essential workflow fails when the API is removed, throttled, or denied, then the remote dependency is part of the product evidence trail. If the call is merely convenient, optional, or outside the intended function, it is easier to argue it is not part of the CRA story.

That is why teams should document the function chain, not just the endpoint list. A remote service can sit outside the visible UI and still be central to the product’s operation if it supplies decisions, data, or control actions the product cannot replicate locally.

How should teams build a defensible CRA evidence story?

Use evidence that ties the remote service to intended product behaviour, then show who owns it and how it is maintained. A strong evidence set usually includes architecture diagrams, product requirements, dependency inventories, release notes, and operational records that show the service is not incidental. The aim is to prove function, design intent, and lifecycle responsibility, not just connectivity.

Security teams should also separate evidence about the product from evidence about the organisation’s wider service estate. A shared platform, a third-party API, or a managed backend may still matter if it is necessary for the product to function. That means the evidence story should explain why the dependency is product-relevant, how changes are controlled, and what happens when the service fails or changes behaviour.

When the dependency is remote, OWASP API Security Top 10 is a useful reminder that authentication, authorisation, and exposure issues can be part of the product’s security story, not just the API team’s problem. For broader product security evidence, the EU Cyber Resilience Act makes the lifecycle question explicit: if the digital element is part of the marketed product, it needs evidence that design, maintenance, and vulnerability handling are being managed as part of the product itself.

What usually causes teams to overstate or understate CRA scope?

The most common mistake is treating anything “cloud-based” as automatically in scope, or the opposite, treating anything not shipped as code as automatically out of scope. Both approaches fail the product-function test. The better question is whether the API or remote service is necessary for the product’s intended use and whether the manufacturer is responsible for its design or ongoing maintenance.

Teams also understate scope when they focus only on the visible application surface and ignore remote processing that changes output, policy, safety, or access decisions. They overstate scope when they include every third-party service their product can reach, even when those services are peripheral and not part of the product’s intended function. The evidence story should distinguish core dependencies from optional integrations.

Remote dependencies are easiest to defend when you can show clear ownership, a stable release process, and a direct link between the service and the product requirement it fulfils. If that link is weak or undocumented, the evidence case usually becomes fragile.

Practitioner Guidance

What to verify: Confirm that the API or remote service is named or implied in the product’s intended-function evidence, not just in a network or inventory record. Then verify that the manufacturer can demonstrate maintenance responsibility, change control, and failure behaviour for that dependency.

Decision rule: If removing the remote service breaks a feature the product is designed to provide, treat it as evidence-relevant. If the service is optional, ancillary, or only used for convenience, keep it separate from the core CRA evidence narrative unless another requirement makes it material.

Practitioner takeaway: CRA evidence should follow product function, not deployment shape. When a remote service is part of how the product works, teams need proof of design intent, maintenance ownership, and dependency control, because that is what makes the scope defensible.

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