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Start for freeDiscovering Hidden GraphQL Endpoints in Web Applications
Hello, everyone! Today, we will delve into an intriguing challenge of identifying and exploiting hidden GraphQL endpoints within web applications. This exploration forms part of the GraphQL API vulnerabilities module, focusing on lab number three from PortSwigger's Web Security Academy. As we venture into this, it's crucial to remember that our discussion is strictly for educational and awareness purposes, adhering to ethical hacking standards.
The Challenge: Finding the Hidden GraphQL Endpoint
The task at hand involves uncovering a concealed GraphQL endpoint responsible for user management functions. Unlike other scenarios where endpoints are discoverable through webpage navigation, this particular endpoint remains hidden, adding a layer of complexity. Additionally, this endpoint implements certain controls against introspection, further complicating its discovery.
Initial Reconnaissance
The first step in any penetration testing, especially with web applications, involves extensive reconnaissance. Gathering as much information as possible about the target application can reveal potential vulnerabilities and attack vectors. Techniques such as subdomain, directory, and file enumeration serve as the starting point for uncovering hidden services, including GraphQL endpoints.
Employing Penetration Testing Tools
Utilizing tools like Burp Suite, we embarked on sending requests to the application, aiming to identify any GraphQL-related endpoints. By manipulating the request paths and employing a brute-force approach with common GraphQL endpoint paths, we stumbled upon a peculiar response from an /API endpoint. This response differed from others, hinting at a possible GraphQL service due to its unique error message indicating a missing query.
Probing with a Universal Query
To confirm our suspicion, we crafted a universal query aimed at every GraphQL service. This query, __typename, is reserved within GraphQL and returns the queried object's type. By sending this query to the suspected endpoint, we received a response characteristic of GraphQL services, solidifying our discovery of the hidden endpoint.
Overcoming Introspection Defenses
Despite identifying the endpoint, the challenge mentioned defenses against introspection, necessitating further steps to retrieve the schema information. By customizing our queries and employing URL encoding techniques, we attempted to bypass these defenses. Modifications to the query structure and the strategic removal of certain directives eventually led to the successful retrieval of the schema information.
Executing the Final Attack
With the schema in hand, our objective shifted to exploiting the identified vulnerabilities. The schema revealed a deleteOrganizationUser mutation, which we targeted to delete a specific user account, as stipulated by the lab's requirements. Through crafting and sending the appropriate mutation query, we successfully deleted the user account, achieving our goal and completing the lab.
Conclusion
This exploration through finding and exploiting hidden GraphQL endpoints offers valuable insights into the complexities of web application vulnerabilities. It underscores the importance of thorough reconnaissance, the effective use of penetration testing tools, and the adaptability required to overcome built-in defenses. As we conclude, let's reiterate the importance of ethical hacking practices and the pursuit of knowledge for securing web applications against potential threats.
For those interested in delving deeper into the technicalities and executing the steps firsthand, the original tutorial video provides a comprehensive walkthrough. Watch the full video here.
Remember, the knowledge shared here is for educational purposes only. Always adhere to ethical standards in your cyber security practices.
