server/org.http4s.server.middleware/CSRF

CSRF

final class CSRF[F[_], G[_]] extends CSRFPlatform[F, G]

Middleware to avoid Cross-site request forgery attacks. More info on CSRF at: https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)

This middleware is modeled after the double submit cookie pattern: https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)_Prevention_Cheat_Sheet#Double_Submit_Cookie

When a user authenticates, embedNew is used to send a random CSRF value as a cookie. (Alternatively, an authenticating service can be wrapped in withNewToken).

By default, for requests that are unsafe (PUT, POST, DELETE, PATCH), services protected by the validated method in the middleware will check that the csrf token is present in both the header headerName and the cookie cookieName. Due to the Same-Origin policy, an attacker will be unable to reproduce this value in a custom header, resulting in a 403 Forbidden response.

By default, requests with safe methods (such as GET, OPTIONS, HEAD) will have a new token embedded in them if there isn't one, or will receive a refreshed token based off of the previous token to mitigate the BREACH vulnerability. If a request contains an invalid token, regardless of whether it is a safe method, this middleware will fail it with 403 Forbidden. In this situation, your user(s) should clear their cookies for your page, to receive a new token.

The default can be overridden by modifying the predicate in validate. It will, by default, check if the method is safe. Thus, you can provide some whitelisting capability for certain kinds of requests.

We'd like to emphasize that you please follow proper design principles in creating endpoints, as to not mutate in what should otherwise be idempotent methods (i.e no dropping your DB in a GET method, or altering user data). Please do not use the CSRF protection from this middleware as a safety net for bad design.

Value Params
clock

clock used as a nonce

cookieSettings

the CSRF cookie settings

headerName

your CSRF header name

key

the CSRF signing key

Companion
object
trait CSRFPlatform[F, G]
class Object
trait Matchable
class Any

Value members

Concrete methods

def checkCSRF(r: Request[G], http: F[Response[G]]): F[Response[G]]

Check for CSRF validity for an unsafe action.

Check for CSRF validity for an unsafe action.

def checkCSRFToken(r: Request[G], respAction: F[Response[G]], rawToken: String)(implicit F: Async[F]): F[Response[G]]

Check for CSRF validity for an unsafe action.

Check for CSRF validity for an unsafe action.

Exposed to users in case of manual plumbing of csrf token (i.e websocket or query param)

def createRequestCookie(token: CSRFToken): RequestCookie
def createResponseCookie(token: CSRFToken): ResponseCookie

Create a Response cookie from a signed CSRF token

Create a Response cookie from a signed CSRF token

Value Params
token

the signed csrf token

def embedInRequestCookie(r: Request[G], token: CSRFToken): Request[G]
def embedInResponseCookie(r: Response[G], token: CSRFToken): Response[G]
def embedNewInResponseCookie[M[_]](res: Response[G])(implicit evidence$1: Async[M]): M[Response[G]]

Embed a token into a response

Embed a token into a response

def generateToken[M[_]](implicit F: Async[M]): M[CSRFToken]

Generate a new token

Generate a new token

def getHeaderToken(r: Request[G]): Option[String]
def onfailureF: F[Response[G]]
def refreshOrCreate[M[_]](r: Request[G])(implicit F: Async[M]): EitherT[M, CSRFCheckFailed, CSRFToken]

Extract a CsrfToken, if present, from the request, then try generate a new token signature, or fail with a validation error. If not present, generate a new token

Extract a CsrfToken, if present, from the request, then try generate a new token signature, or fail with a validation error. If not present, generate a new token

Returns

newly refreshed token

def refreshedToken[M[_]](r: Request[G])(implicit F: Async[M]): EitherT[M, CSRFCheckFailed, CSRFToken]

Extract a CsrfToken, if present, from the request, then try to generate a new token signature, or fail with a validation error

Extract a CsrfToken, if present, from the request, then try to generate a new token signature, or fail with a validation error

Returns

newly refreshed token

def validate(predicate: Request[G] => Boolean): (F, Request[G], Response[G], Request[G]) => Response[G]

Constructs a middleware that will check for the csrf token presence on both the proper cookie, and header values, if the predicate is not satisfied

Constructs a middleware that will check for the csrf token presence on both the proper cookie, and header values, if the predicate is not satisfied

If it is a valid token, it will then embed a new one, to effectively randomize the complete token while avoiding the generation of a new secure random Id, to guard against BREACH

Inherited methods

def extractRaw[M[_]](rawToken: String)(implicit F: Async[M]): M[Either[CSRFCheckFailed, String]]

Decode our CSRF token, check the signature and extract the original token string to sign

Decode our CSRF token, check the signature and extract the original token string to sign

Inherited from
CSRFPlatform
def signToken[M[_]](rawToken: String)(implicit F: Async[M]): M[CSRFToken]

Sign our token using the current time in milliseconds as a nonce Signing and generating a token is potentially a unsafe operation if constructed with a bad key.

Sign our token using the current time in milliseconds as a nonce Signing and generating a token is potentially a unsafe operation if constructed with a bad key.

Inherited from
CSRFPlatform