Field Test CSRF vulnerability

The Field Test dashboard is vulnerable to cross-site request forgery (CSRF) with non-session based authentication methods in versions v0.2.0 through v0.3.2.

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.