GraphQL introspection leads to sensitive data disclosure.

Eshan Singh
Oct 30, 2019 · 3 min read


Hello World! I’m Eshan Singh, aka R0X4R. I’m that hacker teenager that your friends told you about. I hack web-server to make the system secure. I’m here to share my recent findings on GraphQL Introspection.

What is GraphQL

All of us know that Facebook uses its own query language to store its data properly. So, according to GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. GraphQL provides a complete and understandable description of the data in your API, gives clients the power to ask for exactly what they need, and nothing more, makes it easier to evolve APIs over time, and enables powerful developer tools.

About this vulnerability

For Discovering this bug, I learned the fundamentals of GraphQL for at least 5–6 hours and read all other relevant bug reports, especially Namhamsec’s GraphQL CTF Challenge.

After that, I saw a new program on Bugcrowd, so I participated in it. They gave me a domain [let’s take the domain as because the vulnerability hasn’t fixed yet], i.e. So I make an account on that domain, then fire burpsuite and added for spidering; after 10–20 secs, I saw that the, so I got an idea that uses Graphql for their API management.


Tools that I used in this

  • Burpsuite
  • Burpsuite Extensions — JSON Beautifier and GraphQL Raider
  • A Web Browser [Firefox] :P

How I got the vulnerability

First I logged out and logged in again on, then I went to the ‘Update Profile’ section and changed my name from Eshan Singh to Singh Eshan and clicked save. And, then intercepted that request and sent it repeater, then I saw something interesting i.e.

__typename with PayRollAdmin, so I replaced it with xyz then I again send the request and then checked the response xyz reflects on PayRollAdmin place.

So, for digging more into this, I googled GraphQL Exploits, then I saw a Hackerone disclosed the vulnerability, i.e. So I thought let’s try the same that this guy did on this report.

I googled Introspection GraphQL Payloads, and I got this from PayloadAllTheThings repo:

Then I copied the payload and pasted it on graphql tab in burpsuite and sent the request, and walla! I got a juicy response.


Impact of this

The application is basically used by payrolls and HR. So when I exploit it I was able to retrieve receipt of transactions and users passwords phone numbers and more

Thanks and regards

Eshan Singh [R0X4R]

Signing out…

Eshan Singh

Written by

Hi.. I’m that hacker teenager that your friends told you about. I hack to make system secure. Hacker — Developer — Influencer — Graphics Designer

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