Why API security matters to modern businesses

Most modern products are not a single application. They are a web front end, a mobile app and a set of internal services, all talking to each other through APIs. Every one of those connections is a potential entry point, which is why API-specific weaknesses now account for a large share of real-world breaches.

The most common API weaknesses

Broken object-level authorisation (BOLA) is the most frequent issue in practice: an API correctly checks that a user is logged in, but does not check that the object they are requesting actually belongs to them. Changing an ID in a request can expose another customer's data. Excessive data exposure is close behind — endpoints that return full internal objects and rely on the client to hide fields the user should not see.

Why this is easy to miss internally

Engineering teams test the flows the product actually uses. Attackers test the flows the API technically allows. A mobile app might only ever request its own records, but if the underlying endpoint accepts any ID, the restriction only exists in the app, not the API. Internal QA rarely finds this because it never has a reason to try.

Where to start

A focused API review maps every endpoint, tests authorisation on each one with a second, unprivileged account, and checks what each response actually contains versus what the client displays. This is usually a bounded, well-scoped piece of work rather than an open-ended audit.