There are two proposals for enhancing CSRF attacks in JSF. We need to pick one.

Why? I think it's actually safer to allow both: http://www.owasp.org/index.php/Cross-Site_Request_Forgery_%28CSRF%29_Prevention_Cheat_Sheet#Disclosure_of_Token_in_URL. According to this, appending the token works better when you can't guarantee that a server-side operation is occurring only through POST. Especially with the new capabilities of JSF 2 for parsing view parameters, I don't think we can make this guarantee.

Also, the rewriting approach is what they're using for the generic filter in Tomcat 7: http://www.owasp.org/index.php/Cross-Site_Request_Forgery_%28CSRF%29_Prevention_Cheat_Sheet#Disclosure_of_Token_in_URL. I was talking to Mark Thomas, the guy working on this feature, about this at JavaOne. As you can see, it doesn't even look like they're using the hidden field approach (probably because it'd be very hard to implement in a generic fashion).

So, I think we should provide both features, but give the users to turn off either algorithm, with a context parameter such as:

javax.faces.CSRF_ALGORITHM=NONE | FORM | URL | BOTH (or ALL)

This proposal does the following: - Token is generated on the server consisting (minimally) of a randomly generated "secret key" (stored in session). The token can be generated upon session creation, or, at the time the token hidden field and/or token Url parameter is produced. - Standard context parameter javax.faces.CSRF_ALGORITHM controls where the token is produced by the following values: a. "form" : token is produced as the value of the hidden field with the name <form client id>:javax.faces.Token where <form client id> is the enclosing form's client identifier (produced with getClientId) - i.e. the hidden field is namespaced using the form's client identifier. b. "url" : token is produced and appended as a parameter to the form's action Url with the same name as in [a]. c. "all" : token is produced as in [a] *and* [b] d. "none" : no token is produced The default is [a] "form". - After render time, a subsequent action will send the token to the server. - Restore View Phase processing compares the incoming token request parameter value with the token value generated from the secret key in the session. Spec Document Modifications: Section 7.5.1: getActionURL: The returned URL must contain the parameter with a name consisting of the form's fully namespaced client identifier, the NamingContainer.SEPARATOR_CHAR and the constant defined by ResponseStateManager.VIEW_TOKEN_PARAM, if the configuration option javax.faces.CSRF_ALGORITHM is set to "url" or "all". The value of this parameter, known as the "token value" must be a cryptographically produced random generated value (known as the "secret key") retrieved from the session. If the "secret key" does not already exist in the session, create the random value and store it in the session. Implementations may choose to produce a more complex token value by combining the random "secret key" with other values. Section 2.2.1 "If the value of the configuration option javax.faces.CSRF_ALGORITHM is not "none" verify the "javax.faces.Token" request parameter value is the same as the token value generated from the "secret key" stored in the session. If the values do not match, throw a meaningful exception. The exception message must not include the token value." Standard RenderKit Docs - Form Rendering Render a hidden field named javax.faces.Token using the ResponseStateManager.VIEW_TOKEN_PARAM constant if the configuration option javax.faces.CSRF_ALGORITHM is set to the key words "form" or "all". The name must be namespaced with the enclosing form's client identifier. Render the value of this hidden field, known as the "token value", as a cryptographically produced random generated value (known as the "secret key") retrieved from the session. If the "secret key" does not already exist in the session, create the random value and store it in the session. Implementations may choose to produce a more complex token value by combining the random "secret key" with other values. Implementation Changes are attached to this issue: [1] https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=869 -roger