How I Discovered an API Security Vulnerability in a Staging Environment (and What You Can Learn from It)

About Me

I’m Satyam Pawale, better known in the bug bounty world as @hackersatty. I started my bug hunting journey in 2024, and since then, I’ve been deeply passionate about uncovering security flaws that others might overlook. My style of hunting is a mix of manual creativity and technical precision, which often helps me find vulnerabilities in places others ignore.

My toolkit includes Burp Suite, Postman, custom scripts, and plenty of Google Dorks — but my main weapon is curiosity.

This blog is about how I found a critical API security vulnerability in a staging environment. I’ll take you through the exact step-by-step process, from spotting the Swagger UI to crafting the proof of concept. By the end, you’ll know how to:

• Identify exposed APIs.

• Test them safely.

• Report them professionally for maximum impact.

• PAID VULNERABILITIES

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Introduction: Why APIs Are a Treasure Trove for Bug Hunters

When people talk about bug bounty hunting, they often think of XSS, SQLi, or CSRF. But in the modern web, APIs (Application Programming Interfaces) are one of the richest attack surfaces.

Why?

• APIs handle direct requests from clients to backend systems.

• Many APIs are under-secured because developers focus on functionality first.

• Staging APIs are often less monitored, yet connected to production data.

In this case, I found an API Security Vulnerability that allowed account creation and password reset without authentication — a bug that could have led to serious damage if abused.

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Step 1 – The Discovery: How I Stumbled Upon the Swagger UI

It all started when I was testing a program’s staging domain:

I wasn’t expecting much — many staging environments are dead. But I always follow this golden rule:

“If it’s in scope, it’s worth checking.”

I typed the URL in my browser, and to my surprise, instead of a blank page or 403 error, I saw:

Swagger UI — a graphical API documentation tool.

![Swagger UI Example Image Placeholder]

Now, Swagger UI is not bad in itself. In fact, it’s meant to help developers test their APIs easily. But in the wrong hands, it can become a recon goldmine.

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Step 2 – Reading the API Endpoints Like a Map

When I opened the Swagger interface, I saw multiple endpoints under categories like:

• /User/createUser

• /User/resetPassword

• /Application/createApplication

And here’s where my brain went:

• Create User without authentication? Could be account spamming.

• Reset Password without login? That’s instant account takeover.

• Create Application? Might lead to abuse or resource exhaustion.

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Step 3 – Testing the Create User Endpoint

Swagger allows you to send requests directly from its interface. I clicked on /User/createUser, and it showed me the parameters needed:

I filled in my test email and hit Execute.

To my surprise, I got a 200 OK response and a message saying “User created successfully” — all without logging in or providing an API key.

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Step 4 – Realising the Impact

At this point, I knew I had found something serious. This API Security Vulnerability could allow:

1. Mass Account Creation:
   An attacker could flood the system with fake accounts, possibly causing outages or messing with analytics.

2. Credential Stuffing Support:
   If password reset endpoints were also unauthenticated, accounts could be hijacked.

3. Privilege Escalation:
   If new accounts had unintended access, the attacker could directly reach admin areas.

4. Staging-to-Production Risk:
   If staging shared databases with production (a common misconfiguration), this could directly compromise real users.

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Step 5 – Expanding the Test

After creating a user, I checked other endpoints:

• /User/resetPassword — It let me request password resets without logging in.

• /Application/createApplication — Could create resources without checks.

This confirmed a lack of authentication across multiple critical endpoints.

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Step 6 – How This Happens in Real Life

This is actually common in development:

• Developers disable authentication in staging to make testing easier.

• They forget to secure Swagger UI or block it from the public.

• The staging environment is left online, sometimes even pointing to production data.

For attackers, this is a dream scenario.

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Step 7 – Proof of Concept (PoC)

Here’s the exact POST request (with safe dummy data) that demonstrated the bug:

Response:

No authentication headers. No security checks.

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Step 8 – Reporting the Bug

I wrote my report with the following sections:

1. Title: Unauthenticated API endpoints in staging environment allowing account creation and password reset.

2. Description: Explained what I found, how it could be abused, and potential business impact.

3. Steps to Reproduce: Detailed each action.

4. PoC: Included exact requests and responses.

5. Impact: Account creation spam, account takeover risk, possible production compromise.

6. Recommendations: Secure all endpoints, restrict Swagger UI, run regular API audits.

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Step 9 – Company’s Fixes

The company responded quickly:

• Authentication added to all sensitive endpoints.

• Swagger UI restricted to internal access.

• Security review conducted for all staging APIs.

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Step 10 – Lessons You Can Apply

Here’s what I want you to remember:

• Staging ≠ Safe — Always treat staging like production.

• Swagger UI can leak critical endpoints.

• Authentication is non-negotiable for sensitive APIs.

• Automate recon to detect open Swagger UIs (hint: Shodan dork http.title:"Swagger UI").

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Pro Tips for Finding API Bugs (Advanced)

1. Look for Keywords in JS Files:
   api_key, token, auth often reveal endpoints.

2. Wayback Machine Recon:
   Old API docs sometimes still work.

3. Check CORS Configurations:
   Misconfigured CORS + open API = easy data theft.

4. Subdomain Permutations:
   If staging-api exists, try dev-api, beta-api, qa-api.

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Coming Soon on Hackersatty.com

For premium readers, I’ll be sharing:

• Custom Google Dorks for API discovery

• My personal API recon cheatsheet

• Swagger UI exploitation methodology

Stay tuned — these will be members-only resources.

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Final Thoughts

Finding this API Security Vulnerability was a huge learning moment. It proved that:

• Curiosity pays off.

• Staging environments can be as dangerous as production if left open.

• Even simple tests can reveal high-impact bugs.

If you take one thing from this blog, let it be this:

“Never ignore staging. Sometimes, it’s the backdoor to the kingdom.”

Until next time — happy hunting! 😊