Rails Cross-Site Request Forgery

A CSRF forgery vulnerability exists in rails < 5.2.5, rails < 6.0.4 that makes it possible for an attacker to, given a global CSRF token such as the one present in the authenticity_token meta tag, forge a per-form CSRF token. (2020-07-02, CVE-2020-8166)

A CSRF vulnerability exists in rails <= 6.0.3 rails-ujs module that could allow attackers to send CSRF tokens to wrong domains. (2020-06-19, CVE-2020-8167)

The absence of Anti-CSRF tokens may lead to a Cross-Site Request Forgery attack that can result in executing a specific application action as another logged in user, e.g. steal their account by changing their email and password or silently adding a new admin user account when executed from the administrator account.

The attacker may copy one of your web application forms, e.g. email/password change form.

The webpage will contain a form with the exact set of fields as the original application but with input values already provided and the submit button replaced with a Javascript code causing auto-submission. When the page is accessed the form will be immediately submitted and page contents replaced with a valid content or a redirect to your original application.

One of your application users who is already logged in can be then tricked to navigate to such malicious page e.g. by clicking a link in a phishing email, and the pre-populated form content will be submitted to your application like it would be submitted by your user.