If you want, “SameSite=Strict” may also be helpful and is supported on “all” browsers so it is reasonable to use it (but like you did, adding server validation is always a +).
I find that cookie setting really confusing. It means that cookies will only be respected on requests that originated on the site that set them... but that includes when you click links from one site to another.
So if you follow a link (e.g. from a Google search) to a site that uses SameSite=Strict cookies you will be treated as logged out on the first page that you see! You won't see your logged in state until you refresh that page.
I guess maybe it's for sites that are so SPA-pilled that even the login state isn't displayed until a fetch() request has fired somewhere?
You want lax for the intuitive behavior on navigation requests from other origins. Because there’s no assumption navigation get requests are safe, strict is available as the assumption-free secure option.
Note SameSite=Strict also counts against referrals too, which means your first request will appear unauthenticated. If this request just loads your SPA skeleton, that might be fine, but if you're doing SSR of any sort, that might not be what you want.
Right now the problem is what the author already mentions - the use of Sec-Fetch-Site (FYI, HTTP headers are case insensitive :) - is considered defense in depth in OWASP right now, not a primary protection.
Unfortunately OWASP rules the world. Not because it's the best way to protect your apps, but because the corporate overloads in infosec teams need to check the box with "Complies with OWASP Top 10"
This was actually a mistake. If you look at the OWASP cheat sheet today you will see that Fetch Metadata is a top-level alternative to the traditional token-based protection.
I'm not sure I understand why, but the cheat sheet page was modified twice. First it entered the page with a top-level mention. Then someone slipped a revision that downgraded it to defense in depth without anyone noticing. It has now been reverted back to the original version.
I'm surprised there's no mention of the SameSite cookie attribute, I'd consider that to be the modern CSRF protection and it's easy, just a cookie flag:
Most of them. You can send in a cookie and a field and compare.
CSRF is about arbitrary clicks in emails and such that automagic your logged-in-session cookies to the server. If you require an extra field and compare it, you’re fine
Am I missing something? The suggested protection helps with XSS flavors of CSRF but not crafted payloads that come from scripts which have freedom to fake all headers. At that point you also need an oauth/jwt type cookie passed over a private channel (TLS) to trust the input. Which is true for any sane web app, but still…
CSRF exists as a consequence of insecure-by-default browser handling of cookies, whereby the browser sends the host’s cookies on requests initiated by a third-party script to the vulnerable host. If a script can fake all headers, it’s not running in a browser, and so was never exposed to the insecure browser cookie handling to be able to leverage it as a vector. If no prerequisite vector, then no vulnerability to mitigate.
If an attacker has a user's private authentication token, usually stored in a __Host prefixed cookie, then it's game over anyway. CSRF is about protecting other sites forcing a user to make a request to a site they're authenticated to, when the malicious doesn't actually have the cookie/token.
CSRF is when you don't have the authentication token, but can force a user to make a request of your choosing that includes it.
As I understand it, the moment you’re dealing with custom scripts, you’ve left the realm of a csrf attack. They’re dependent upon session tokens in cookies
https://caniuse.com/mdn-http_headers_set-cookie_samesite_str...
This checks Scheme, Port and Origin to decide whether the request should be allowed or not.
So if you follow a link (e.g. from a Google search) to a site that uses SameSite=Strict cookies you will be treated as logged out on the first page that you see! You won't see your logged in state until you refresh that page.
I guess maybe it's for sites that are so SPA-pilled that even the login state isn't displayed until a fetch() request has fired somewhere?
Unfortunately OWASP rules the world. Not because it's the best way to protect your apps, but because the corporate overloads in infosec teams need to check the box with "Complies with OWASP Top 10"
This was actually a mistake. If you look at the OWASP cheat sheet today you will see that Fetch Metadata is a top-level alternative to the traditional token-based protection.
I'm not sure I understand why, but the cheat sheet page was modified twice. First it entered the page with a top-level mention. Then someone slipped a revision that downgraded it to defense in depth without anyone noticing. It has now been reverted back to the original version.
Some details on what happened are in this other discussion from a couple of days ago: https://news.ycombinator.com/item?id=46347280.
https://scotthelme.co.uk/csrf-is-dead/
But I didn't know about the Sec-Fetch-Site header, good to know.
CSRF is about arbitrary clicks in emails and such that automagic your logged-in-session cookies to the server. If you require an extra field and compare it, you’re fine
CSRF is when you don't have the authentication token, but can force a user to make a request of your choosing that includes it.