GraphQL pentesting

👉 Overview

👀 What ?

GraphQL is a data query and manipulation language for APIs, and a runtime for fulfilling those queries with your existing data. It provides an efficient and powerful alternative to REST and offers significant advantages when it comes to dealing with data. GraphQL Pentesting refers to the process of testing GraphQL APIs for potential vulnerabilities and security flaws.

🧐 Why ?

GraphQL's ability to fetch many resources in a single request, its real-time updates, and its overall efficiency make it an enticing choice for developers. However, these same features can potentially provide an expansive attack surface if not properly secured. This is why GraphQL Pentesting is crucial—it aids in identifying potential vulnerabilities in a GraphQL API, ensuring the safety of the data it handles.

⛏️ How ?

GraphQL Pentesting can be initiated by exploring the GraphQL schema, which provides an attacker a blueprint of the data structure. Potential attack vectors can include Injection Attacks, exploiting poorly implemented access controls, and excessive data exposure. Tools like GraphiQL, GraphQL Playground and Burp Suite can be used for testing. Also, it's recommended to follow a methodology: Reconnaissance, Mapping, Discovery, and Exploitation for a systematic pentesting.

⏳ When ?

Pentesting should be performed during the development phase to catch vulnerabilities early, and it should be part of an ongoing security strategy post-deployment. With the rise of GraphQL's popularity in recent years, the need for efficient and thorough GraphQL Pentesting has become more crucial.

⚙️ Technical Explanations

GraphQL operates using a singular HTTP endpoint, unlike REST APIs that utilize multiple endpoints. This characteristic simplifies the exploration of the API surface area. The capabilities of the API are defined by GraphQL schemas that provide a comprehensive map of all data that can be accessed through the API.

An attacker can use an Introspection query to reveal the schema. This step is crucial as it enables the attacker to gain detailed insights into the data structure. Once the schema is revealed, the attacker can search for sensitive data that might be exposed, test for Injection attacks, or attempt to bypass authorization checks.

Injection attacks refer to the insertion of malicious data that can lead to data breaches. These attacks are possible when an application that constructs GraphQL queries allows a user to supply unfiltered data, which is then included in a query to the server.

Bypassing authorization checks refers to the attacker exploiting weaknesses in the system to access unauthorized data. This can occur if the API allows client-side data fetching, which can lead to over-fetching or under-fetching attacks.

A thorough GraphQL Pentesting includes all these steps and uses a mix of automated tools and manual testing for optimal results. Automated tools, such as GraphiQL, GraphQL Playground, and Burp Suite, can be used to perform various tasks such as sending queries, mutating data, and testing for vulnerabilities. Manual testing is also crucial as it can help identify issues that automated tools might miss. It involves a step-by-step review of the code and data structure to identify potential vulnerabilities.

In conclusion, GraphQL Pentesting is a comprehensive process that involves understanding the GraphQL schema, exploring exposed data, testing for potential vulnerabilities, and using a combination of automated and manual techniques to ensure the security of the API.

Let's consider a simple example of GraphQL Pentesting on a hypothetical API that fetches user profiles.

1. Exploration: First, we use introspection to reveal the API's schema. The introspection query can look something like this:

query {
  __schema {
    types {
      name
      fields {
        name
        type {
          name
        }
      }
    }
  }
}

This query will return all types and fields available in the API.

1. Identifying Data Exposure: From the introspection query result, we spot a UserProfile type with fields including username, email, and password. The existence of password is a red flag, indicating potential excessive data exposure.
2. Testing for Injection Attacks: We construct a query to fetch user profiles and supply unfiltered data to test for potential injection attacks. The query might look like this:

{
  UserProfile (username: "admin' OR '1'='1") {
    username
    email
    password
  }
}

If the server responds with data, it indicates an injection vulnerability.

1. Bypassing Authorization Checks: We also test if we can fetch data that we shouldn't have access to. Suppose we're logged in as a regular user but try to fetch admin users' data:

{
  UserProfile (role: "admin") {
    username
    email
    password
  }
}

If the server responds with admin users' data, it means there are weaknesses in the authorization checks.

1. Tools for Testing: Throughout these stages, we utilize tools like GraphiQL for sending queries and analyzing responses, and Burp Suite for automating and managing the testing process.

In summary, GraphQL pentesting involves exploring the API using introspection, identifying potential data exposure, testing for vulnerabilities like injection attacks, and bypassing authorization checks, all while using both automated tools and manual code review.