Cross Site Request Forgery

By enabling the CSRF Component you get protection against attacks. CSRF or Cross Site Request Forgery is a common vulnerability in web applications. It allows an attacker to capture and replay a previous request, and sometimes submit data requests using image tags or resources on other domains.

The CsrfComponent works by setting a cookie to the user’s browser. When forms are created with the Cake\View\Helper\FormHelper, a hidden field is added containing the CSRF token. During the Controller.startup event, if the request is a POST, PUT, DELETE, PATCH request the component will compare the request data & cookie value. If either is missing or the two values mismatch the component will throw a Cake\Network\Exception\InvalidCsrfTokenException.

Note

You should always verify the HTTP method being used before executing side-effects. You should check the HTTP method or use Cake\Network\Request::allowMethod() to ensure the correct HTTP method is used.

Using the CsrfComponent

Simply by adding the CsrfComponent to your components array, you can benefit from the CSRF protection it provides:

public function initialize()
{
    parent::initialize();
    $this->loadComponent('Csrf');
}

Settings can be passed into the component through your component’s settings. The available configuration options are:

  • cookieName The name of the cookie to send. Defaults to csrfToken.
  • expiry How long the CSRF token should last. Defaults to browser session. Accepts strtotime values as of 3.1
  • secure Whether or not the cookie will be set with the Secure flag. That is, the cookie will only be set on a HTTPS connection and any attempt over normal HTTP will fail. Defaults to false.
  • field The form field to check. Defaults to _csrfToken. Changing this will also require configuring FormHelper.

When enabled, you can access the current CSRF token on the request object:

$token = $this->request->getParam('_csrfToken');

Integration with FormHelper

The CsrfComponent integrates seamlessly with FormHelper. Each time you create a form with FormHelper, it will insert a hidden field containing the CSRF token.

Note

When using the CsrfComponent you should always start your forms with the FormHelper. If you do not, you will need to manually create hidden inputs in each of your forms.

CSRF Protection and AJAX Requests

In addition to request data parameters, CSRF tokens can be submitted through a special X-CSRF-Token header. Using a header often makes it easier to integrate a CSRF token with JavaScript heavy applications, or XML/JSON based API endpoints.

Disabling the CSRF Component for Specific Actions

While not recommended, you may want to disable the CsrfComponent on certain requests. You can do this using the controller’s event dispatcher, during the beforeFilter() method:

public function beforeFilter(Event $event)
{
    $this->eventManager()->off($this->Csrf);
}