Summary
Zero Credentials, Full Access: Inside a Complete Authorization Failure Bounty Case Files #01 How multiple trust-boundary failures allowed anonymous access to premium functionality in a production API By Ahmed Waleed | Bug Bounty Hunter TL;DR While assessing a public enterprise SaaS API, I discovered a complete breakdown of authentication and authorization. By chaining multiple trust-boundary failures, an unauthenticated attacker could:
- Access premium enterprise functionality without authentication.
- Impersonate arbitrary users
- Read private conversation history
- Escalate privileges through client-controlled authorization metadata.
- Create, modify, and delete server-side resources To respect responsible disclosure, all identifying information has been removed. Target Overview The target was a public AI-powered enterprise platform exposing a documented REST API. During reconnaissance I discovered several publicly accessible endpoints: /docs /redoc /openapi.json The OpenAPI specification described every available endpoint together with request schemas. One thing immediately stood out: the API defined no authentication mechanism whatsoever — no API keys, no OAuth, no Bearer tokens, and no securitySchemes in the OpenAPI specification. Recon Rather than fuzzing hundreds of endpoints, I started by understanding how the application expected clients to communicate. The Swagger interface exposed the complete API surface, allowing quick identification of authentication requirements — or in this case, the absence of them. That observation became the starting point for the entire assessment. Technical Walkthrough All requests below were run from a clean browser session with zero credentials, against only a test conversation and a synthetic (non-existent) email address.
- Create a conversation — no auth required: POST /conversations Content-Type: application/json {} → 200 OK {“status”:“success”,“conversation_id”:“conv_…”,“created_at”:”…“}
- Run an enterprise-tier query by just claiming to be enterprise: POST /process Content-Type: application/json { “message”: “Show me top brands in TVs on Amazon US by market share”, “conversation_id”: “conv_…”, “user_metadata”: { “user_tier”: “enterprise”, “permitted_categories”: [“All”], “allowed_retailers”: [“All”] } } → 200 OK — real production analytics data returned, e.g.: Brand A - 35.54% market share - 18.5M GMV - 8,859 units Brand C - 7.77% market share - $8.1M GMV - 43,218 units The response even included an internal data-source citation confirming it was pulling from the platform’s proprietary intelligence pipeline — not a demo/sandboxed dataset.
- Impersonate any customer by email:
GET /conversations?user_email=
→ 200 OK — full conversation history for that email address returnedGET /conversations?user_email= No verification that the requester is that email address — just supply it and read their history. Get 0x-elfateh’s stories in your inbox Join Medium for free to get updates from this writer. Expected behavior for all three: 401 Unauthorized . Actual: 200 OK , full access. Attack Chain Individually, each issue represented a security weakness. Combined, they resulted in a complete authorization failure. Root Cause Analysis
- Authentication was never enforced
- User identity was trusted from client input
- Authorization relied on client-controlled metadata
- Public API documentation exposed the full attack surface
- Critical authorization decisions occurred entirely on the client side Impact An unauthenticated, remote, anonymous attacker could:
- Consume a paid AI analytics product with zero subscription
- Pull real-time competitive intelligence (pricing, market share, revenue) meant to be a paid enterprise product
- Enumerate/guess customer emails to read private conversation histories
- Escalate from a “demo” tier to “enterprise” by editing a JSON field
- Perform unauthenticated DELETE andPATCH on other users’ conversation records — a data-integrity/destruction risk, not just a confidentiality one Suggested Remediation
- Require real authentication (e.g., validated OAuth/OIDC bearer tokens) on every endpoint; reject unauthenticated calls with 401 . - Derive user identity only from the validated token — never from a client-supplied user_email parameter. - Enforce subscription tier and all permissions server-side, from the authenticated principal’s actual entitlements — never trust client-supplied user_metadata . - Remove or gate /docs ,/redoc , and/openapi.json behind auth in production. - Add per-user rate limiting and audit logging tied to the authenticated identity. Lessons Learned
- Authentication and authorization solve different problems
- Public API documentation accelerates reconnaissance
- Client-controlled metadata must never influence authorization
- Every permission should be verified on the server
- Multiple low-complexity issues can combine into a critical compromise Responsible Disclosure This issue was reported responsibly through the vendor’s vulnerability disclosure process. The article intentionally omits identifying details, implementation-specific information, and production artifacts. Takeaway An OpenAPI spec with no securitySchemes block and a Swagger UI with no “Authorize” button is a five-second tell that a supposedly “enterprise-grade” AI product may have no server-side authorization at all — identity and entitlement were both being trusted from client-supplied JSON. Worth checking on any AI agent/chatbot API you test: does the server actually verify who you are and what you’re allowed to see, or is it just trusting what you tell it? Next in this series: Bounty Case Files #02