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

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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.

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1. Create a conversation — no auth required:

POST /conversations
Content-Type: application/json 
{}→ 200 OK
{"status":"success","conversation_id":"conv_...","created_at":"..."}

2. 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 - $36.9M GMV - 47,832 units
Brand B - 17.81% 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.

3. Impersonate any customer by email:

GET /conversations?user_email=<any-email>→ 200 OK — full conversation history for that email address returnedGET /conversations?user_email=<any-email>

No verification that the requester is that email address — just supply it and read their history.

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Expected behavior for all three: 401 Unauthorized. Actual: 200 OK, full access.

Attack Chain

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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 and PATCH 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