How do I "log out" a user? Know that this is not officially supported, but I need a quick and dirty hack. Saw somewhere I just throw out a 401 access denied - but anyone know the syntax
http://httpd.apache.org/docs/1.3/howto/auth.html#basicfaq
Since browsers first started
implementing basic authentication,
website administrators have wanted to
know how to let the user log out.
Since the browser caches the username
and password with the authentication
realm, as described earlier in this
tutorial, this is not a function of
the server configuration, but is a
question of getting the browser to
forget the credential information, so
that the next time the resource is
requested, the username and password
must be supplied again. There are
numerous situations in which this is
desirable, such as when using a
browser in a public location, and not
wishing to leave the browser logged
in, so that the next person can get
into your bank account.
However, although this is perhaps the
most frequently asked question about
basic authentication, thus far none of
the major browser manufacturers have
seen this as being a desirable feature
to put into their products.
Consequently, the answer to this
question is, you can't. Sorry.
As you can see from the full explanation above, you can't.
The only workaround is to invalidate the user session and cause the browser to request username and password again.
Additionally, you can try (I haven't tried it yet) to empty the WWW-Authenticate HTTP header.
Related
I'm experiencing some trouble with an ASP.NET MVC 5 application that has been buggering me for a few days.
The application is using Forms Authentication to control whether a user is Authenticated, and Session to keep track of the user's data.
A few of our users are unable to log in, and I have been able to recreate the problem on a collegue's device. We don't know much about the devices with the problems, except that they all seem to be running iOS. I can't seem to nail down the pattern, though, as one user who reported the problem was running 11.2.5, which I am also running myself without trouble. The collegue's device is running 11.3 beta, but I haven't yet heard of any other users with this version, so I'm unable to pin point that as the problem - which also seems unlikely when one of the users with the problem is running 11.2.5.
The issue happens after the users try logging in. After a successful login, the user is redirected to a specific section of the site, where Authentication is required. Requesting any page in this section redirects you to the login page if you are not Authenticated.
Some of the resources that are requested on this page expect to retrieve some data from Session. For some reason, the Session cookie may sometimes be missing, and other times the Authorization cookie is missing.
For the past few days while I have been hunting this, my collegue's device happened to leave out the Session cookie when requesting our Cachemanifest, in which we expect to be able to generate a specific part based on some data from the Session. This caused the generation to fail, which in turn caused the request to fail.
After changing the generation logic to work around this, with a different solution if the Session cookie is missing, my collegue's device has changed its approach; Now, it includes the Session cookie when requesting this resource, but instead leaves out the Authorization cookie in a subsequent request to a different resource, which is still in the section that requires Authorization. This resource happens to be mentioned in the Cachemanifest, and because this next request does not include the Authorizaiton cookie, that request is redirected to the login page, which is interpreted by the Cachemanifest as an error.
As far as I recall, I haven't changed anything else, so I'm really at a loss as to why this devices' behaviour has changed.
Both of these cookies are included in other requests before and after the failing request, and there doesn't seem to be a pattern between what requests is chooses to leave these two cookies out of, or which cookies to leave out. The only thing that is consistent is that the behaviour doesn't change when retrying after clearing the browser data (only after I made my change, which I still don't see how could result in this behaviour).
The site is forcing HTTPS, so I tried setting the Session cookie to Secure, but that didn't seem to make a difference.
I still need to try setting the Authorization cookie to Secure, but I'm not very optimistic there. I also still need to try reverting my changes to see if the old behaviour reappears.
Has anybody experienced similar problems before, or does anybody have any further suggestions? I know I might be a bit sparse on the details, I'd be happy to provide any further details if I'm able.
Thank you in advance :)
I've got a ASP.NET MVC web app which uses forms authentication.
I'm using ActiveDirectoryMembershipProvider to validate users against our domain.
if (Membership.ValidateUser(m.Username, m.Password))
{
FormsAuthentication.SetAuthCookie(m.Username, true);
....
This means the user gets validated only when they log in.
Problem with that is ofcourse that if the user's password changes they still remain logged in. Or worse, user leaves our company with a grudge, and they still have access.
I would have thought such a simple use case would have an obvious answer but I've been stuck on this for a while now.
I could put the users password in the session and then validate it every time, but that doesn't feel right.
What is the suggested/correct way of handling this?
The typical solution is to force log out when users unsubscribes from the service or less commonly when they change password. Use this method:
FormsAuthentication.SignOut();
FormsAuthentication.RedirectToLoginPage();
If the user can be deactivated outside of the app (i.e. Active Directory), the typical practice is to rely on the session time-out and perhaps ask for the credentials once more for critical operations. If you absolutely cannot allow the deactivated user to work while the session is still active, then yes, you'll have to check the credentials on every request. Since storing the password in the app is a very bad idea, it means you'll have to ask for credentials on each request which arguably is an even worse idea.
As for the password change, it normally doesn't modify the user's permissions so it should be harmless to allow for them to continue working.
The answer is to periodically (every 30 minutes or so) check User.IsApproved and User.LastPasswordChangedDate to make sure the users credentials are still valid.
To do this you need to manually create the FormsAuthenticationTicket and cookie, rather than using FormsAuthentication.SetAuthCookie.
Put the date you validated the user inside UserData and compare this against LastPasswordChangedDate.
I've implemented this and it works perfectly.
More information here
Check if Active Directory password is different from cookie
I'm having an odd problem with my sessions. I haven't found a solution even after searching through the internet for a couple of days and I find it really strange that nobody else seems to be having this problem, which makes me think that it could be something I'm doing wrong.
If I log onto my website and visit a page decorated with the [Authorize] attribute (i.e. it requires the user to have logged on in order to access it), save the request with fiddler, log out and re-issue the request with fiddler one would expect that to fail (or re-direct me to the login page at least) but no, it returns the page as if I were still logged in.
When I'm logging out this is what I do (I'm using asp.net forms authentication)
FormsAuthentication.SignOut();
Session.Clear();
Session.Abandon();
Session.RemoveAll();
Response.Cookies.Add(new HttpCookie("ASP.NET_SessionId",""));
That should work... but it doesn't.
In case anyone is wondering this is what I am using:
IIS 7.5
MVC 3.0
.NET 4.0
If I log onto my website and visit a page decorated with the [Authorize] attribute (i.e.
it requires the user to have logged on in order to access it), save
the request with fiddler, log out and re-issue the request with
fiddler one would expect that to fail
Why would you expect something like this? Forms authentication uses cookies to track logged in users. When you do FormsAuthentication.SignOut(); all that happens is that you remove the authentication cookie so that on subsequent requests from this browser the cookie is no longer sent and the server thinks that the user is not logged in. If on the other hand you have captured a valid cookie with Fiddler, you are perfectly capable of sending a valid request to the server (in the time for which this cookie is valid obviously). There is nothing on the server for it to know that you used fiddler, right? It's completely stateless.
If you wanted to avoid this behavior (which is by design) you will have to keep track somewhere on the server either a list of online users, or add some flag in the database about the user which indicates whether he is online or not. Then you will write a custom Authorize attribute that will check in this centralized store whether the user is allowed or not to login. When he logs out you will change this flag. Obviously if he closes his browser you won't be able to change the flag but if he signs out normally you will know that even if someone had captured the authentication cookie, he will not be able to use it to issue a valid request.
Scenario:
Upon starting a session on my site, I generate a rand token that is shown to the user that once. Say they “store” it away for later use.
I then, INSERT the md5(token) into SQL with timestamp.
When the user visits other pages like login, they would have to pass the token via URL as part of the validation process. I would check to see if the token exist and maybe UPDATE userid to this token.
So. Even if someone steals a user’s PHPSESSID cookie, wouldn’t it do ANY good to the hacker since they can’t access any of these pages without knowing the token?
You are right that they won't be able to access the pages without the token, but as an added point, sometimes I'd like to use IP tracking or browser tracking used concurrently as well.
The rationale being that even if someone gets a PHPSESSID cookie and the token, he would have to be coming from the same IP source as well as use the same browser. Then again these are just means of security by obscurity.
I recommend if you are really concerned about security, you can try looking at using a HTTPS connection. Hope it helped. Cheers!
We are attempting to integrate an ASP.NET MVC site with our client's SSO system using PingFederate. I would like to use the built in FormsAuthentication framework to do this. The way I've gone about it so far is:
Set up my Web.config so that my FormsAuthentication LoginURL goes to my site's "BeginAuthentication" action on a "Security" controller. From this action, I set up some session variables (what URL was being accessed, for example, since Ping won't send this info back to me), and then redirect to our client's login page on an external site (www.client.com/Login for example).
From here, the authentication takes place and a cookie is generated on the same domain as the one that our application is running on which contains the unique identifier of the authenticated user, I've set it up so that once this happens, the Ping server will redirect to my "EndAuthentication" action on my "Security" controller.
In this action, I call my membership class's "ValidateUser" method which takes this unique identifier from the cookie and loads in the user on our application that this ID refers to. I save that logged in user in our Session (Session["LoggedInAs"], for example) and expire the cookie that contains the id of the authenticated user that the SSO system provided for me.
All of this works well. The issue I'm wondering about is what happens after our user has already authenticated and manually goes back to our client's login page (www.client.com/login) and logs in as another user. If they do that, then the flow from #2 above to number 3 happens as normal - but since there already exists an authenticated user on our site, it seems as though the FormsAuthentication system doesn't bother kicking off anything so I don't get a chance to check for the cookie I'm looking for to login as this new user. What I'd like to do is, somewhere in my Global.asax file (probably FormsAuthenticate_OnAuthenticate), check to see if the cookie that the SSO system sends to me exists, and if so, sign out of the application using FormsAuthentication.SignOut().
Another issue that seems to be related is that if I let my Session expire, the FormsAuthentication still seems to think I am authenticated and it lets me access a page even though no currently logged in user exists in my Session, so the page doesn't render correctly. Should I tap into the Session_End event and do FormsAuthentication.SignOut() here as well?
Basically, I want to know when the authentication ticket created by
System.Web.Security.FormsAuthentication.SetAuthCookie(..) gets checked in the flow of a request so that I can determine whether I need to SignOut() and force revalidation or not.
Thanks for any help. Sorry for the length of this message, trying to be as detailed as possible.
Mustafa
Welcome to the small section of Hades that is mixing session with formsauth.
If your needs are as complex as presented, you would get more sleep if you implement a full provider stack to share amongst the participating sites. Easier said than done, I know.
But to address your question:
from http://www.codeproject.com/Articles/39026/Exploring-Web-config-system-web-httpModules.aspx
On the way in....Check ticket and set identity #
app.AuthenticateRequest += System.Web.Security.FormsAuthenticationModule.OnEnter-->OnAuthenticate
On the way out... set the ticket and redirect as necessary
app.EndRequest += System.Web.Security.FormsAuthenticationModule.OnLeave
Reflector is your friend. ;-)
I don't know about a specific event for when the cookie is checked, but you could place the appropriate logic in Application_BeginRequest() and check the user's authentication state there.
Another issue that seems to be related
is that if I let my Session expire,
the FormsAuthentication still seems to
think I am authenticated and it lets
me access a page even though no
currently logged in user exists in my
Session, so the page doesn't render
correctly.
The life of the cookie (how long until ASP.NET feels it needs to ask for a password again) and how you are managing state are unrelated. The ASP.NET authentication is cookie based so that, should a developer want to, he could turn off viewstate, session, use no query strings or hidden fields and authentication still works.
If you want to tie the interval at which you request the password to how you are persisting data, then you will want your session expiration to be roughly the same as the cookie expiration, but they will never quite match up. It would be better to have two policies (one for how fast you throw away a users session data and one for how long you are willing to wait before you need to reask for a password)