When it was first developed, System.Web.Mvc.AuthorizeAttribute was doing the right thing -
older revisions of the HTTP specification used status code 401 for both "unauthorized" and "unauthenticated".
From the original specification:
If the request already included Authorization credentials, then the 401 response indicates that authorization has been refused for those credentials.
In fact, you can see the confusion right there - it uses the word "authorization" when it means "authentication". In everyday practice, however, it makes more sense to return a 403 Forbidden when the user is authenticated but not authorized. It's unlikely the user would have a second set of credentials that would give them access - bad user experience all around.
Consider most operating systems - when you attempt to read a file you don't have permission to access, you aren't shown a login screen!
Thankfully, the HTTP specifications were updated (June 2014) to remove the ambiguity.
From "Hyper Text Transport Protocol (HTTP/1.1): Authentication" (RFC 7235):
The 401 (Unauthorized) status code indicates that the request has not been applied because it lacks valid authentication credentials for the target resource.
From "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content" (RFC 7231):
The 403 (Forbidden) status code indicates that the server understood the request but refuses to authorize it.
Interestingly enough, at the time ASP.NET MVC 1 was released the behavior of AuthorizeAttribute was correct. Now, the behavior is incorrect - the HTTP/1.1 specification was fixed.
Rather than attempt to change ASP.NET's login page redirects, it's easier just to fix the problem at the source. You can create a new attribute with the same name (AuthorizeAttribute
) in your website's default namespace (this is very important) then the compiler will automatically pick it up instead of MVC's standard one. Of course, you could always give the attribute a new name if you'd rather take that approach.
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = true)]
public class AuthorizeAttribute : System.Web.Mvc.AuthorizeAttribute
{
protected override void HandleUnauthorizedRequest(System.Web.Mvc.AuthorizationContext filterContext)
{
if (filterContext.HttpContext.Request.IsAuthenticated)
{
filterContext.Result = new System.Web.Mvc.HttpStatusCodeResult((int)System.Net.HttpStatusCode.Forbidden);
}
else
{
base.HandleUnauthorizedRequest(filterContext);
}
}
}
How to handle authentication in a RESTful Client-Server architecture is a matter of debate.
Commonly, it can be achieved, in the SOA over HTTP world via:
- HTTP basic auth over HTTPS;
- Cookies and session management;
- Token in HTTP headers (e.g. OAuth 2.0 + JWT);
- Query Authentication with additional signature parameters.
You'll have to adapt, or even better mix those techniques, to match your software architecture at best.
Each authentication scheme has its own PROs and CONs, depending on the purpose of your security policy and software architecture.
HTTP basic auth over HTTPS
This first solution, based on the standard HTTPS protocol, is used by most web services.
GET /spec.html HTTP/1.1
Host: www.example.org
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
It's easy to implement, available by default on all browsers, but has some known drawbacks, like the awful authentication window displayed on the Browser, which will persist (there is no LogOut-like feature here), some server-side additional CPU consumption, and the fact that the user-name and password are transmitted (over HTTPS) into the Server (it should be more secure to let the password stay only on the client side, during keyboard entry, and be stored as secure hash on the Server).
We may use Digest Authentication, but it requires also HTTPS, since it is vulnerable to MiM or Replay attacks, and is specific to HTTP.
Session via Cookies
To be honest, a session managed on the Server is not truly Stateless.
One possibility could be to maintain all data within the cookie content. And, by design, the cookie is handled on the Server side (Client, in fact, does even not try to interpret this cookie data: it just hands it back to the server on each successive request). But this cookie data is application state data, so the client should manage it, not the server, in a pure Stateless world.
GET /spec.html HTTP/1.1
Host: www.example.org
Cookie: theme=light; sessionToken=abc123
The cookie technique itself is HTTP-linked, so it's not truly RESTful, which should be protocol-independent, IMHO. It is vulnerable to MiM or Replay attacks.
Granted via Token (OAuth2)
An alternative is to put a token within the HTTP headers so that the request is authenticated. This is what OAuth 2.0 does, for instance. See the RFC 6749:
GET /resource/1 HTTP/1.1
Host: example.com
Authorization: Bearer mF_9.B5f-4.1JqM
In short, this is very similar to a cookie and suffers to the same issues: not stateless, relying on HTTP transmission details, and subject to a lot of security weaknesses - including MiM and Replay - so is to be used only over HTTPS. Typically, a JWT is used as a token.
Query Authentication
Query Authentication consists in signing each RESTful request via some additional parameters on the URI. See this reference article.
It was defined as such in this article:
All REST queries must be authenticated by signing the query parameters
sorted in lower-case, alphabetical order using the private credential
as the signing token. Signing should occur before URL encoding the
query string.
This technique is perhaps the more compatible with a Stateless architecture, and can also be implemented with a light session management (using in-memory sessions instead of DB persistence).
For instance, here is a generic URI sample from the link above:
GET /object?apiKey=Qwerty2010
should be transmitted as such:
GET /object?timestamp=1261496500&apiKey=Qwerty2010&signature=abcdef0123456789
The string being signed is /object?apikey=Qwerty2010×tamp=1261496500
and the signature is the SHA256 hash of that string using the private component of the API key.
Server-side data caching can be always available. For instance, in our framework, we cache the responses at the SQL level, not at the URI level. So adding this extra parameter doesn't break the cache mechanism.
See this article for some details about RESTful authentication in our client-server ORM/SOA/MVC framework, based on JSON and REST. Since we allow communication not only over HTTP/1.1, but also named pipes or GDI messages (locally), we tried to implement a truly RESTful authentication pattern, and not rely on HTTP specificity (like header or cookies).
Later Note: adding a signature in the URI can be seen as bad practice (since for instance it will appear in the http server logs) so it has to be mitigated, e.g. by a proper TTL to avoid replays. But if your http logs are compromised, you will certainly have bigger security problems.
In practice, the upcoming MAC Tokens Authentication for OAuth 2.0 may be a huge improvement in respect to the "Granted by Token" current scheme. But this is still a work in progress and is tied to HTTP transmission.
Conclusion
It's worth concluding that REST is not only HTTP-based, even if, in practice, it's also mostly implemented over HTTP. REST can use other communication layers. So a RESTful authentication is not just a synonym of HTTP authentication, whatever Google answers. It should even not use the HTTP mechanism at all but shall be abstracted from the communication layer. And if you use HTTP communication, thanks to the Let's Encrypt initiative there is no reason not to use proper HTTPS, which is required in addition to any authentication scheme.
Best Answer
You need to send a valid Forms Authentication cookie along with the request. This cookie is usually sent by the server when authenticating (
LogOn
action) by calling the[FormsAuthentication.SetAuthCookie
method (see MSDN).So the client needs to perform 2 steps:
LogOn
action by sending the username and password. In turns this action will call theFormsAuthentication.SetAuthCookie
method (in case the credentials are valid) which in turn will set the forms authentication cookie in the response.[Authorize]
protected action by sending along the forms authentication cookie it retrieved in the first request.Let's take an example. Suppose that you have 2 API controllers defined in your web application:
The first one responsible for handling authentication:
and the second one containing protected actions that only authorized users can see:
Now we could write a client application consuming this API. Here's a trivial console application example (make sure you have installed the
Microsoft.AspNet.WebApi.Client
andMicrosoft.Net.Http
NuGet packages):And here's how the 2 HTTP requests look on the wire:
Authentication request:
Authentication response:
Request for protected data:
Response for protected data: