CSRF Vulnerability with Non-Session Based Authentication

[ankane]

The Field Test dashboard is vulnerable to cross-site request forgery (CSRF) with non-session based authentication methods. This vulnerability has been assigned the CVE identifier CVE-2020-16252.

Versions Affected: 0.2.0 to 0.3.2
Fixed Versions: 0.4.0

Impact

The Field Test dashboard is vulnerable to CSRF with non-session based authentication methods, like basic authentication. Session-based authentication methods (like Devise's default authentication) are not affected.

A CSRF attack works by getting an authorized user to visit a malicious website and then performing requests on behalf of the user. In this instance, a single endpoint is affected, which allows for changing the variant assigned to a user.

All users running an affected release should upgrade immediately.

Technical Details

Field Test uses the protect_from_forgery method from Rails to prevent CSRF. However, this defaults to :null_session, which has no effect on non-session based authentication methods. This has been changed to protect_from_forgery with: :exception.