web browser – CSRF Security Independent From Front-End

Yes, one method of ensuring CSRF protection is to check the Origin and Referrer headers to see whether they match the expected origin, as these headers cannot be overwritten by any frontend code. However, the origin header is only sent on POST or CORS requests, and the browser implementations of these headers have historically not been consistent; e.g. possibly allowing JavaScript to spoof one or more of the headers (modern browsers should behave correctly, although I cannot speak for the future spec or implementation).

This protection only requires implementing a server-side check on every POST request. It is important to deny the request if the sent origin doesn’t match, or if none was sent at all.

The OWASP CSRF Cheat Sheet includes some reasons for why you may not want to use this method exclusively. However, if you face none of those restrictions, I personally feel that this method is okay to use in lieu of a more complex method.