API Security & Monitoring

Broken object level authorisation, often called BOLA or IDOR, is the single most common serious API flaw. An endpoint returns a record based on an ID in the request but never checks whether the caller owns that record, so changing the ID hands over someone else’s data. Close behind sit broken authentication, function-level authorisation gaps where a normal user can call an admin action, and excessive data exposure where an API returns full objects and trusts the client to hide the sensitive fields. These are logic problems, and logic is what monitoring built for APIs actually watches.

Most companies expose more APIs than they document. Old versions still running, endpoints spun up for a mobile app and never retired, internal APIs that quietly became reachable. These shadow APIs are prime targets precisely because nobody is watching them. Discovery comes first, mapping your real API surface across REST and GraphQL, so monitoring covers everything you expose rather than only the endpoints someone remembered to list.

We baseline how each endpoint is used: which callers hit it, how often, what data volumes are normal, which sequences of calls make sense. Against that baseline, abuse becomes visible. One account enumerating thousands of object IDs, a token suddenly calling endpoints it never touched, a response returning ten times the usual number of records. None of these trip a signature; all of them stand out against a learned baseline.

If you have an OpenAPI specification, it is a contract for how the API should behave, and departures from it are suspicious. We validate live traffic against the schema so calls with unexpected parameters, malformed payloads or responses leaking fields the spec never declared are flagged. For GraphQL, we watch for the deep and abusive queries that a single flexible endpoint makes possible.

APIs live and die by tokens. We watch for tokens used from unexpected locations, replayed after they should have expired, or exercising privileges beyond their scope, all signs of theft or an authorisation flaw. Because a stolen API token can bypass a login entirely, this is one of the highest-value things to monitor.

Runtime protection at the gateway

Monitoring tells you what is happening; runtime protection lets you act on it. Working with your API gateway and WAF, we apply rate limiting, block confirmed abuse, and throttle enumeration in real time, so a detected attack is contained rather than merely logged. We tune the rules to your traffic so legitimate integrations are never caught in the net.

A coupon endpoint applied a thousand times, a transfer API called in a sequence that skips a validation step, a checkout flow manipulated to change a price the server should have set. Every request is well-formed and authenticated. The abuse is in the logic and the sequence, which is why business-logic attacks slip past scanners and generic firewalls and why monitoring has to understand intent, not just syntax.

APIs make bulk data extraction easy for an attacker who finds an endpoint that returns records by ID. Steady, patient enumeration can quietly lift your entire dataset without ever looking like an attack in any single request. Detecting it means spotting the pattern across many calls, exactly the kind of thing a per-request defence cannot see.

In authorised API penetration tests we hunt for BOLA, broken authentication, function-level authorisation gaps and business-logic abuse manually, because these need human judgement, not a scanner. That experience shapes the monitoring we build: we know which patterns signal a real authorisation flaw being exploited, so the alerts are meaningful rather than a stream of noise about every unusual request.

Monitoring catches attacks in progress; testing finds the holes before anyone attacks them. We often pair the two, using a manual API assessment to find and fix the flaws, then monitoring to catch exploitation of anything that slips through or appears in the next release. That closes the loop far more effectively than either alone.

Every API is different, so its normal behaviour and its abuse look different. We tune the baselines and rules to your specific endpoints and traffic, which is the work that separates useful monitoring from an alert firehose. You should hear about real problems and not much else.

An API leaking personal data through excessive exposure or a BOLA flaw is a GDPR breach waiting to happen, and DORA expects financial entities to secure and monitor the ICT systems, including APIs, that carry their services. Where APIs touch cardholder data, PCI DSS applies. We document the monitoring and map it to the OWASP API Security Top 10 so your auditors and your customers’ security questionnaires get concrete answers.

Enterprise customers increasingly ask how you secure and monitor your APIs before they integrate. Being able to show real coverage, not a vague assurance, removes a common blocker to closing the deal.