Definition

API security testing for payments and open-banking APIs evaluates authentication, authorisation, input validation, rate limiting, and data exposure across REST, GraphQL, and SOAP interfaces, using the OWASP API Security Top 10 2023 as the primary framework. In Gulf open-banking contexts, this includes testing OAuth 2.0 and FAPI-compliant flows mandated by SAMA Open Banking Framework and CBUAE Open Finance regulations, as well as PCI DSS v4.0 Requirement 6.3 controls for payment-handling endpoints.

Why it matters

The pressure on VAPT programmes is shifting in specific, observable ways:

• SAMA Open Banking Framework v1.1 (2022) and CBUAE Open Finance Framework require TPP-facing APIs to demonstrate security testing evidence; BOLA (OWASP API1:2023) and broken authentication (API2:2023) are the most common findings in Gulf open-banking tests.
• PCI DSS v4.0 Requirement 6.2.4 mandates that all payment-processing APIs undergo security testing before production deployment; failure to evidence this during QSA assessment results in a compensating control requirement.
• OWASP API3:2023 (Broken Object Property Level Authorization) enables mass-data-harvesting attacks; one Gulf fintech lost AED 4.2M in fraudulent transactions attributed to a BOLA flaw undiscovered until a regulatory-mandated pentest.
• ISO/IEC 27001:2022 Annex A 8.29 requires security testing of APIs as part of secure development; documented OWASP API Top 10 evidence satisfies auditor requests during ISO certification assessments.

Evidence sources to capture

What an auditor or reviewer will sample for — wire each source into your evidence repository before the next review cycle:

• OpenAPI/Swagger spec file — endpoint inventory, parameter definitions, authentication schemes used as test baseline
• Postman collection export — all tested request/response pairs with injected payloads (BOLA object IDs, auth token swaps)
• Burp Suite project file — API-specific scanner issues, manual BOLA test chains, rate-limit bypass sequences
• OAuth 2.0 / FAPI token logs — access token issuance, scope grants, client-ID audit trail from authorisation server (e.g. Keycloak or ForgeRock)
• API gateway access log (AWS API Gateway / Apigee) — rate-limit trigger events, 401/403 response patterns, anomalous request volume
• OWASP API Top 10 test matrix — API ID, endpoint, risk category, result, CVSS score, remediation owner

Recommended next actions

A 90-day plan, sequenced so each step produces evidence the next step depends on:

• Day 0–30: AppSec Lead exports OpenAPI spec for all payment/open-banking APIs; maps each endpoint to OWASP API Top 10 2023 categories; identifies authentication type (API key, OAuth 2.0, mTLS) per endpoint.
• Day 31–60: Tester executes BOLA tests across all object-reference endpoints, broken-auth tests against OAuth flows using Burp Suite and Postman; documents rate-limit bypass attempts with evidence screenshots.
• Day 61–90: Developer team patches Critical findings (BOLA, broken authentication, excessive data exposure); AppSec Lead retests patched endpoints; FAPI compliance validated using Conformance Suite (openid.net).
• Day 90+: Compliance Manager packages OWASP API Top 10 test report for SAMA/CBUAE open-banking regulatory evidence file; archive alongside OAuth audit logs.
• Ongoing: Integrate 42Crunch API security audit into CI/CD pipeline; run automated OWASP API Top 10 scan on every API version release.

Example metrics

Instrument these and report them monthly to the executive sponsor; sustained adverse trends become board-level conversations:

• BOLA (API1:2023) findings per engagement in open-banking APIs: industry average 1.8; target 0 post-remediation
• API endpoint coverage in test (tested / total from OpenAPI spec): target ≥95%
• Rate-limit enforcement: all payment endpoints must return HTTP 429 after ≤100 requests/minute from single client
• OAuth token lifetime for open-banking access tokens: target ≤15 minutes (FAPI 1.0 Advanced guidance)
• Critical/High API findings closed within 14 days: target 100%

A the next two quarters working plan

MAST Consulting Group runs this VAPT work in four moves. Each move is short, evidence-producing, and signed off by a Lead Practitioner before the next begins.

• Frame (week 1). Confirm scope, regulators in play, and the decisions the work has to enable — referenced against the rules of engagement (RoE). Without that framing, the rest becomes a documentation exercise the audit committee will not read.
• Diagnose (weeks 2–4). Walk through retest letter and scope and RoE as they exist today. Capture not just gaps but the design decisions behind every existing control — those are usually where audit findings hide.
• Design (weeks 5–8). Make the contested choices early and pre-clear them with regulators that require independent penetration testing (PCI DSS 11.4, SAMA, ADGM/DIFC, RBI). Document the rationale; VAPT reviewers care more about reasoned decisions than perfect ones.
• Operate (weeks 9–12). Move evidence collection into MobSF and Frida (mobile) and Postman / OpenAPI fuzzers (APIs). A control that depends on a separate GRC tool nobody opens will fail within two cycles.

Pitfalls we keep seeing

Across MAST Consulting Group's VAPT portfolio, the same recurring failure modes show up cycle after cycle. None are exotic; all are expensive when they reach the audit report.

• Pattern: findings without business impact, only CVSS scores. What good looks like: the same control evidenced inside the workflow it governs, not separately for the audit.
• Pattern: missing chain-of-attack narrative for critical findings. What good looks like: the same control evidenced inside the workflow it governs, not separately for the audit.
• Pattern: no retest budget agreed up front. What good looks like: the same control evidenced inside the workflow it governs, not separately for the audit.
• Pattern: scope written so loosely it invites scope creep mid-test. What good looks like: the same control evidenced inside the workflow it governs, not separately for the audit.

Tooling we actually reach for

MAST Consulting Group is deliberately tool-agnostic, but in practice the same shortlist keeps appearing on VAPT engagements because the integrations are cheap and the evidence is defensible:

• Burp Suite Pro — used not because it is fashionable, but because the audit trail it generates is one the reviewer accepts on the first ask.
• Nuclei — used not because it is fashionable, but because the audit trail it generates is one the reviewer accepts on the first ask.
• MobSF and Frida (mobile) — used not because it is fashionable, but because the audit trail it generates is one the reviewer accepts on the first ask.

How MAST Consulting Group can help

MAST Consulting Group runs VAPT programmes for banks, insurers, healthcare networks, payments providers, telcos and government entities across the UAE, KSA, India and the wider GCC. We bring Lead Practitioners, sector specialists, and a working library of policies, risk methodologies and evidence templates that have passed audit at firms recognisable to your board.

If anything in this playbook is relevant to a programme you are scoping or rescuing, the fastest next step is a 30-minute working session with the practice lead. We will look at your specific situation, share what we have seen work for VAPT programmes at similar scale, and tell you honestly if the work is something you should bring to us or run in-house.