> 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-with-start-of-path-validation.md).
# 起始路径验证的路径遍历
起始路径验证的路径遍历，PortSwigger Web Security Academy 实验笔记，包括利用流程、载荷测试、Burp Suite 验证以及修复上下文。
### 文件路径遍历，路径起始部分的校验
应用程序通过查询参数传输整个文件路径，并且只检查该路径 **的开头** 是否与预期文件夹匹配。这种校验是不够的：在允许的前缀后追加内容后，就有可能访问任意文件。
#### **分析**
文件名参数直接包含一个绝对路径，例如：
```bash
/var/www/images
```
如果尝试经典的穿越：
```bash
../../../../../etc/passwd
```
应用程序会阻止它。
但是如果我们提供 **预期路径**，后面跟着 `../` 用于逃逸的序列，校验就无法检测到越界：
由于路径起始部分与 `/var/www/images/`完全匹配，检查会通过，但最终解析实际上指向 `/etc/passwd`.
```bash
/var/www/images/../../../../../etc/passwd
```
---
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