How a 17-Year-Old Found 3 SQL Injection Vulnerabilities on Mastercad Using GraphQL

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A 17-year-old security researcher discovered three SQL injection vulnerabilities in a well-known domain (redacted) by exploiting misconfigured GraphQL endpoints. The discovery began with routine reconnaissance, where the researcher noticed GraphQL functionality—a potential goldmine for security testing due to its introspective nature.

Key Steps in the Discovery:

1. GraphQL Schema Mapping:

  • Collected all accessible queries and mutations.
  • Used introspection to fetch the schema (__schema query). 
    query IntrospectionQuery { 
__schema { 
queryType { name } 
mutationType { name } 
types { ...FullType } 
} 
}

2. Fuzzing Parameters:

  • Tested each parameter for SQLi using payloads like: 
    ' OR 1=1 --
  • Automated with tools like ClairvoyanceX (for schema extraction despite disabled introspection).

3. Exploitation & Reporting:

  • Verified vulnerabilities via manual testing.
  • Reported responsibly to the vendor (patched).

You Should Know: GraphQL Security Testing

1. Enumerate GraphQL Endpoints

  • Common paths: /graphql, /graphiql, /v1/graphql.
  • Use curl to check introspection: 
    curl -X POST -H "Content-Type: application/json" --data '{"query":"{__schema{queryType{name}}}"}' http://target.com/graphql

2. Extract Schema (Even if Introspection is Disabled)

  • Tools:
  • ClairvoyanceX (bypasses disabled introspection).
  • GraphQLmap: 
    python3 graphqlmap.py -u http://target.com/graphql -v

3. Test for SQL Injection

  • Use sqlmap with GraphQL: 
    sqlmap -u "http://target.com/graphql" --data='{"query":"query { user(id: \"1\") { name } }"}' --risk=3 --level=5

4. Mitigations for Developers

  • Disable introspection in production: 
    const server = new ApolloServer({ 
introspection: false, 
playground: false 
});
  • Use query whitelisting.

What Undercode Say

GraphQL’s flexibility makes it prone to misconfigurations. Automated tools like ClairvoyanceX and GraphQLmap simplify exploitation, but ethical disclosure ensures fixes. Key takeaways:
– For Hackers: Always test GraphQL introspection and mutations.
– For Devs: Restrict schema exposure and sanitize inputs.

Expected Output:

  • A patched GraphQL endpoint.
  • Improved security awareness among developers.

Prediction:

  • GraphQL-based attacks will rise as adoption grows—expect more automated exploitation tools.

Relevant URL:

IT/Security Reporter URL:

Reported By: H4x0z How – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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