Inventory the business connection and its real authority
Start with the task: reading a customer’s order, updating stock, creating an invoice or passing a lead to a CRM. Identify the calling system, receiving endpoint, account owner, credential owner and external services. Include old versions, trial connections and scheduled jobs that remain active.
OWASP’s API Security Top 10 for 2023 identifies several distinct risk categories, including authorization, authentication, resource consumption and unsafe use of external APIs. It is a risk framework, not a certificate or a complete specification for every business integration. Use the categories to ask concrete questions about your actual route.
Record where each decision is enforced. A user interface that hides a button does not establish that the API rejects the operation. An integration account with broad administrator rights can exceed the narrow business task even if its normal workflow uses only a few endpoints.
Test object, action and field permission separately
Authentication establishes the identity presented to the service; authorization determines the permitted record and operation. OWASP’s object-level guidance calls for checks on the requested object and action at endpoints that use object identifiers. Guess-resistant identifiers or an authenticated session do not replace that control.
Use synthetic accounts with deliberately different rights and invented records. The original matrix below describes expected acceptance outcomes for a hypothetical customer-order integration. It is a planning aid, not permission to request another customer’s real record or a set of exploit instructions.
| Controlled identity and request | Expected business boundary | Evidence to record |
|---|---|---|
| No authenticated identity requests a protected record | No protected content returned | Server outcome and absence of the invented protected fields |
| Test customer A reads an allowed record | Only authorized record and permitted fields | Expected synthetic fields and response context |
| Test customer B requests A’s invented record | No access to that record | Denial without leaking the record content |
| Read-only integration requests a change | No unauthorized mutation | Rejection and unchanged synthetic target record |
| Operational role requests an administrative action | Role boundary remains enforced | Denied action and appropriately limited logging |
| Permitted edit includes extra sensitive fields | Only approved fields can change | Actual target-state comparison, not just a 2xx response |
Validate the input and minimize the returned information
Agree on accepted fields, types, required values, size limits and business rules for each operation. Validate on the receiving server before using the data. A syntactically correct customer identifier or amount can still be inappropriate for the current identity and task.
Return only the necessary information. A business integration may need an order reference and fulfillment state without full customer history or internal notes. Review file downloads, exports, nested objects and error responses as well as the normal screen. Broad payloads can expose information even when the caller is allowed to use the endpoint.
Treat downstream API data as input requiring checks, not automatically trustworthy material because it came from a known provider. Review how values enter database queries, browser output, files and external operations. Information validation, safe use and authorization are related controls with different jobs.
Control resource use and external costs
Identify operations that can consume substantial compute, storage, messages or provider fees. A request-count limit alone may not bound a large export, expensive search or batched operation. Agree on meaningful limits for the actual task and on what happens when those limits are reached.
OWASP’s resource-consumption guidance discusses payload bounds, rate limits and external-service spending controls or alerts. Apply these at the relevant identity and operation where supported. A business owner needs to know who receives an alert and whether it merely reports spending or actually stops further consumption.
Review pagination, upload sizes, processing time, concurrency and retry behavior with the developer. An acceptance exercise should check supported boundaries using harmless records, not attempt to exhaust a live service. Record unavailable controls as explicit gaps rather than inventing a quota the current product does not enforce.
Manage secrets, callbacks and repeated events across their lifecycle
Record which identity owns each credential, the necessary scope, secure storage, change process and supported revocation route. Do not put keys in browser code, shared spreadsheets or screenshots. A departure or supplier change may require reviewing tokens and service accounts in addition to ordinary login access.
For callbacks, use the provider’s documented authenticity mechanism and check the intended destination, event and business context. Handle delayed or repeated events under an explicit design so they cannot silently duplicate a charge, notification, stock movement or dispatch. A valid signature is not by itself a complete business authorization decision.
Use a supplier handover that separates observations from claims
Ask for the endpoint inventory, identities, granted scopes, relevant validation rules, controlled test results, logging coverage and unresolved issues. Logs should help trace an operation without unnecessarily retaining secrets or complete customer payloads. A model or application narration that it performed an action is weaker evidence than the target system’s actual result.
CyberFixCrew is an Israeli cybersecurity company serving businesses worldwide. Our practical Israeli website and infrastructure knowledge connects APIs, accounts, CRM routes and store integrations into an agreed technical review. Start with the business task and system names; do not send tokens, customer exports or live callback payloads in the initial enquiry.
Agree on the assessment boundary before testing. A scoped integration review is not automatically a full penetration test or a certification of every endpoint. Keep allowed and denied synthetic outcomes, evidence references, remaining limitations and the next owner together so the business can decide what to fix and how to verify it.
