Test the boundary, too.

A service depends on more than the security of its individual parts. I want to know what those parts are trusting each other to do.

Component testing is useful. A business process also depends on the relationships between components: an identity assertion, an API request, a shared credential, or a record passed to another workflow.

The places where one component trusts another deserve deliberate attention.

Find the assumption

A hypothetical downstream service might assume that an upstream application has already checked whether a person may act on a particular record. The upstream team might assume the downstream service performs that check.

Both components can look reasonable in isolation while the authorization decision remains unclear. A test that follows the business action can expose that gap.

Use context to choose the scenario

Work with the people who know the process. Which actions are sensitive? Which systems share authority? Where can an administrator, integration, or automated job cross into a different area?

Then test a defined scenario with agreed access and operating limits. Where the consequences could be disruptive, choose a suitable environment or a controlled exercise.

Make the result a shared responsibility

A boundary finding may not belong neatly to one application team. It still needs a clear owner for the decision, with the contributing teams involved in the fix.

The useful outcome is agreement on where the control belongs, what each component may rely on, and how the relationship will be validated after change.

Trust between systems needs an explicit reason and a place where that reason is enforced.

That is the additional perspective I want offensive security to bring: testing the assumptions that connect an environment, alongside the weaknesses within its individual parts.