API Penetration Testing
Operator-led testing focused on authorization, scopes, and workflow abuse. We prove impact with exploit chains and close with retest evidence in the Bytium workspace.
What you get on day one
Concise scope, test plan, and outcomes your team can execute.
3–5 days
Start-to-test window
Access ready? We move fast.
OAuth2/JWT/HMAC
Auth models covered
Also API keys + custom schemes.
Broken access control
Primary risk focus
BOLA/IDOR, scopes, workflow abuse.
72 hours
Retest turnaround
Per confirmed fix.
Why API pentesting matters
The API operator briefing your backend team expects
We test the API as an untrusted client — validating object-level authorization, scope enforcement, and workflow integrity with exploit chains and replayable request/response evidence.
Authorization is assumed, not proven
Most APIs rely on framework-level checks that silently fail at the object or scope level. We test what actually enforces access — per endpoint, per role, per tenant.
Tokens carry hidden risk
JWTs, OAuth scopes, and API keys often grant broader access than intended. We validate token lifecycle, scope enforcement, and claim integrity across real client flows.
Business logic breaks silently
Workflow abuse, replay attacks, and state machine violations don't trigger scanners. We model your actual business flows and find where valid requests produce invalid outcomes.
Closure needs proof
Retests are scheduled from day one and tracked with updated request/response evidence. Every fix is re-verified so closure is defensible for leadership and audit.
What we test
Risk coverage that matches real API attacks
We test the paths attackers actually take — identity, access control, workflows, and integrations — and prove impact with real requests and responses.
Authentication & tokens
Token replay, refresh abuse, session confusion, key rotation gaps, and weak signing or verification across OAuth2, JWT, HMAC, and custom auth schemes.
Authorization & objects
BOLA/IDOR across endpoints, tenant boundary escape, role and ownership enforcement failures, and inconsistent access control between API versions.
Scopes & permissions
Over-broad OAuth scopes, missing server-side checks, scope escalation paths, JWT claim tampering, and inconsistent enforcement across client types.
Business logic & state
Workflow bypass, order-of-operations flaws, race conditions, replay attacks, idempotency gaps, and abuse of payment, approval, or refund flows.
Enumeration & abuse
Rate-limit bypass, brute force on identifiers, resource exhaustion, predictable IDs, and excessive data exposure in API responses and error messages.
Integrations & webhooks
Partner API trust assumptions, webhook signature bypass, backend-to-backend privilege escalation, and SSRF-like pivots through internal service boundaries.
GraphQL APIs receive dedicated coverage
Resolver authorization, field-level access, query cost limits, introspection exposure, and batching abuse — tested with the same depth as REST endpoints.
Ready when you are
Start an API penetration test
We'll scope your endpoints, test real attacker paths, and verify fixes with retest evidence.
How we test
The API exploit playbook
A repeatable, operator-led approach that produces fewer false positives and clearer fixes than automated scanning.
Auth & role mapping
We model roles, scopes, tenants, and token types the way your real clients use them — web, mobile, partner, and internal. This builds a realistic threat model before any requests are sent.
Endpoint discovery
We enumerate resources, object relationships, hidden endpoints, and version inconsistencies. The goal is full surface visibility, not just what the docs describe.
Authorization pressure
We probe object-level access, scope enforcement, and tenant boundaries across every relevant path. Each test uses real tokens with crafted claims to prove or disprove access control.
Workflow & state abuse
We attack ordering, replay, idempotency, and business rules where the highest-impact issues hide — valid requests that produce unauthorized outcomes.
Exploit chains
We chain individual findings into complete attack narratives proving real business impact, then package proof with request/response evidence engineers can replay.
Retest & closure
Fixes are retested with updated evidence and recorded with pass/fail status. Closure means verified and documented — ready for leadership and audit review.
Deliverables
Evidence that backend teams can use immediately
Replayable request/response proof, exploit narratives, and ownership tracked with retests until closure.
API-specific PoCs
Concrete request/response exploit steps tied to the exact endpoint, method, and control failure.
- Replayable curl/HTTP payloads
- Token and scope context included
- Annotated request/response traces
Exploit narratives
End-to-end attack paths showing how an attacker moves from one weakness to real business impact.
- Chained findings with impact proof
- Authorization boundary maps
- Workflow abuse scenarios documented
Closure evidence
Executive summary plus retest-backed proof that every remediation was verified, not assumed.
- Risk and readiness for leadership
- Updated evidence per fix
- Export-ready for auditors and compliance
Engagement options
Pick the cadence that fits your API change rate
Both options include retests and evidence that stays attached to each finding.
One-time API pentest
A focused, single-scope engagement ideal for a release, audit checkpoint, or partner onboarding. Fast scoping, defined timeline, and verified closure with retests included.
- Defined scope, endpoints, and auth models
- Exploit narratives with request/response proof
- Included retest cycle to verify every fix
API PTaaS
A continuous, release-aligned testing cadence with scheduled windows as endpoints evolve. Evidence stays attached to findings and retests roll forward automatically.
- Testing windows per sprint or quarter
- Cumulative findings library across releases
- Rolling retests tracked to closure with exec packs
FAQ
What teams ask before we start
Do you need OpenAPI/Swagger specs?+
They help accelerate scoping, but they're not required. We can work from Postman collections, developer docs, or live endpoint discovery. Many APIs have undocumented endpoints that matter most.
Can you test internal or backend APIs?+
Yes — internal APIs often carry the highest risk due to implicit trust assumptions and weaker abuse controls. We test backend-to-backend paths, partner integrations, and service mesh boundaries.
Do you test mobile-only API surfaces?+
Yes. We model the mobile client flows and test how attackers craft direct API requests outside the app's intended UI. Certificate pinning bypass and request tampering are included.
Do you test GraphQL APIs?+
Yes. We test resolver-level authorization, field-level access control, query cost and depth limits, introspection exposure, and batching abuse. GraphQL surfaces are tested with the same rigor as REST.
Staging vs production?+
Staging with production-like data and auth models is preferred. Production testing is possible with guardrails, rate limits, testing windows, and approval processes aligned during scoping.
How quickly can we start?+
Most API engagements start within 3–5 business days once access, documentation, and test accounts are confirmed. We align on scope, auth models, and test windows during a fast scoping call.