REST APIs
Endpoint behavior, HTTP methods, object references, filters, pagination, and response handling.
API Security Testing
API Security Testing for SaaS Products
Manual testing for REST and GraphQL APIs, authorization models, token boundaries, object-level access, tenant isolation, and API-driven business logic.
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Request → Scope Discussion → Recommended Review → Testing
REST APIsGraphQL APIsAuthorization ReviewsManual Testing
api.security.map
CallerClientREST / GraphQL
IngressAPI GatewayRoutes + rate limits
IdentityAuthenticationJWT / OAuth
PolicyAuthorizationRole + Object ID
Protected resourceTenant DataDatabase
Object IDToken scopeOwnership
Coverage
API Attack Surface Coverage
Coverage spans REST and GraphQL authorization boundaries, token and scope validation, tenant isolation, response shaping, and valid API actions that can be combined into business logic abuse.
GraphQL APIs
Schemas, resolvers, mutations, nested queries, batching, introspection, and field-level exposure.
Authentication
Login exchanges, session creation, refresh flows, credential recovery, and identity transitions.
Authorization
Role enforcement, object ownership, action permissions, and cross-user or cross-tenant access.
Token Validation
JWT claims, OAuth scopes, signature handling, expiry, audience, and privilege boundaries.
Tenant Isolation
Organization boundaries, shared identifiers, tenant context, and data segregation controls.
Business Logic
Workflow sequencing, state manipulation, replay, limit bypasses, and unintended product actions.
Third-Party Integrations
Webhooks, partner APIs, service credentials, trust assumptions, and external data paths.
Trust Boundary Trace
Where API Risk Usually Appears
A valid token can still cross a tenant boundary when an endpoint trusts a caller-controlled object reference without verifying ownership.
01Client RequestREST or GraphQL
02Token / SessionIdentity accepted
03API EndpointValid product action
04Object IDCaller controlled
05Authorization CheckTenant context requiredMissing ownership validation
06Data ReturnedExposure or workflow abuse
REST + GraphQLToken scopeTenant isolation
Exploit Path
How Modern APIs Get Breached
Attackers often use legitimate sessions and valid API actions. Risk appears when token scope, object ownership, tenant isolation, or workflow rules are enforced inconsistently across the request path.
Validated outcomeCross-tenant sensitive data exposure
01UserLow-privilege account
02Valid SessionJWT accepted
03API RequestAuthorized endpoint
04Object ReferenceID changed by caller
05Missing Authorization CheckOwnership not validated
06Sensitive Data ExposureAnother tenant's record
Common Findings
Common API Vulnerabilities We Identify
Typical findings include excessive data exposure, broken object authorization, scope bypasses, resolver-level GraphQL weaknesses, and business logic abuse that depends on product context.
BOLA-01
IDOR / BOLA
Object identifiers expose records outside the caller's ownership or tenant boundary.
GET /accounts/{id}GQL-02
GraphQL Enumeration
Queries reveal internal IDs, relationships, hidden fields, or account existence signals.
query user(id)AUTHZ-03
Broken Object Authorization
Valid sessions can invoke actions without a matching ownership or policy check.
PATCH /projects/{id}TOKEN-04
Token Scope Failures
JWT or OAuth permissions allow broader reads, writes, or administrative actions than intended.
scope: read:*DATA-05
Excessive Data Exposure
Responses return sensitive fields that the UI does not need and the caller should not receive.
200 response fieldsLOGIC-06
Business Logic Abuse
Legitimate API functions can be sequenced or replayed to bypass product rules and controls.
state transitionTENANT-07
Multi-Tenant Isolation Issues
Tenant context is missing, user-controlled, or inconsistently enforced across endpoints.
X-Tenant-IDINT-08
Insecure Integrations
Webhooks and partner connections trust unsafe input, weak signatures, or overprivileged credentials.
POST /webhooksDeliverable Preview
Example Finding Report
Each finding connects endpoint evidence to product risk, with developer-ready remediation, ownership context, and clear retest criteria.
Evidence-backedEndpoint-specificEngineering-ready
Finding
Broken Object Authorization
Affected endpoint
GET /api/v1/accounts/{id}ImpactCross-tenant data exposure
Root causeMissing ownership validation
RecommendationEnforce authorization checks before record retrieval and bind object access to the authenticated tenant context.
Tenant A userAccount ID BRecord returned
Method
API Review Process
A focused review moves from architecture and role mapping to manual abuse-case testing, evidence-backed reporting, and fix validation.
Scope
Define APIs, roles, tenants, environments, and high-risk product workflows.
Map
Trace schemas, endpoints, identities, trust boundaries, and sensitive data paths.
Test
Run manual authorization, abuse-case, token, GraphQL, and business logic testing.
Validate
Confirm the exploit path, affected users, tenant reach, and practical impact.
Report
Document requests, evidence, reproduction, root cause, and engineering guidance.
Retest
Verify critical fixes and confirm the vulnerable path is no longer reachable.
Difference
Why Automated Scanners Miss These Issues
API risk is often hidden in who can call an action, which object they can reference, and how legitimate functions combine across a workflow.
Pattern and response checks
- Known signatures and configuration checks
- Limited identity and tenant context
- No ownership validation across workflows
- Severity without exploit confirmation
- Generic output requiring interpretation
Manual, context-aware validation
- Workflow testing across roles and tenants
- Authorization and object access validation
- Business logic and abuse-case review
- Exploit confirmation with practical impact
- Developer-ready evidence and guidance
Attack Path Visualization
From Valid Session to Cross-Tenant Data
The request looks legitimate until an object reference crosses a tenant boundary without a matching authorization decision.
01UserLow-privilege role
02Authenticated SessionValid JWT
03API RequestAllowed endpoint
04Object Reference ChangedTenant ID swapped
05Authorization MissingOwnership unchecked
06Cross-Tenant Record ReturnedSensitive data exposed
Output
What You Receive
A concise security deliverable with affected endpoints, exploit evidence, practical fix guidance, and retest criteria for engineering and product stakeholders.
Review outputValidated and prioritized
Ready for engineering handoffReproduction Steps
Requests, role context, prerequisites, and a reliable path engineers can replay.
Impact Analysis
Affected users, tenant reach, exposed data, and the product consequence of exploitation.
Exploit Path
The authorization or workflow failure connecting attacker-controlled input to impact.
Fix Guidance
Practical control recommendations aligned to the endpoint, resolver, or permission model.
Retest Validation
Clear verification criteria and confirmation notes for remediated high-risk findings.
Risk Prioritization
Findings ordered by reachability, exploitability, data sensitivity, and customer impact.
FAQ
API Security Testing FAQ
Answers for teams reviewing REST APIs, GraphQL APIs, authorization boundaries, tenant isolation, and API-driven product risk.
What is API security testing?
API security testing reviews how requests, tokens, roles, object references, and workflows behave when abused by authenticated or unauthenticated users.
Do you test REST and GraphQL APIs?
Yes. Reviews can cover REST endpoints, GraphQL queries and mutations, resolver behavior, token scopes, object-level access, and excessive data exposure.
How is API testing different from normal penetration testing?
API testing focuses deeply on request-level trust boundaries, authorization checks, object ownership, tenant isolation, and machine-readable workflows that scanners often miss.
What API vulnerabilities do you usually find?
Common findings include IDOR/BOLA, broken object authorization, token scope failures, GraphQL enumeration, excessive data exposure, and business logic abuse.
What deliverables are provided?
You receive validated findings with affected endpoints, role context, reproduction steps, impact analysis, fix guidance, and retest criteria.
Next Step
Review the trust boundaries attackers will test first.
Validate authorization, tenant isolation, object access, and the API paths that could expose customer data before they become real attack paths.
AuthorizationTenant IsolationObject AccessAPI Trust Boundaries