[keycloak-dev] Improve back-button and refreshes in authenticators?

Marek Posolda mposolda at redhat.com
Tue Mar 14 16:49:53 EDT 2017

Thanks, that looks similar to my (3) though.

Besides that I wonder if we should save just the ID of loginSession in 
the cookie and the "current-code" keep inside the loginSession 
(infinispan) similarly like it is now?

I am thinking about the case when potential attacker tricks Keycloak by 
manually sending the request, which will just use same code in the 
cookie and in the URL. Keycloak will then always treat this request as 
valid due the code in the URL and in cookie will always match. Couldn't 
that be an issue?


On 14/03/17 13:50, Bill Burke wrote:
> I've got an idea.  What about
> * keep the code in the URL
> * Additionally add a "current-code" cookie
> If code in the URL doesn't match the cookie, then redirect to the URL of
> the current-code.
> On 3/14/17 6:53 AM, Marek Posolda wrote:
>> When working on login sessions, I wonder if we want to improve browser
>> back-button and browser refreshes.
>> In shortcut, I can see 3 basic options:
>> 1) Keep same like now and rely on header "Cache-Control: no-store,
>> must-revalidate, max-age=0" . This works fine and users never saw
>> outdated form and never submit outdated form 2 times. However the
>> usability sucks a bit IMO. When you press back-button after POST
>> request, you can see the ugly browser page "Web page has expired" . And
>> if you press F5 on this, you will see the unfriendly Keycloak error page
>> "Error was occured. Please login again through your application" because
>> of invalid code.
>> 2) Use the pattern with POST followed by the redirect to GET. Since we
>> will have loginSession with the ID in the cookie, the GET request can be
>> sent to the URL without any special query parameter. Something like
>> "http://localhost:8180/auth/realms/master/login-actions/authenticate" .
>> This will allow us that in every stage of authentication, user can press
>> back-button and will be always redirected to the first step of the flow.
>> When he refreshes the page, it will re-send just the GET request and
>> always brings him to the current execution.
>> This looks most user-friendly. But there is the issue with performance
>> though. As we will need to followup every POST request with one
>> additional GET request.
>> 3) Don't do anything special regarding back-button or refresh. But in
>> case that page is refreshed AND the post with invalid (already used)
>> code will be re-submitted, we won't display the ugly page "Error was
>> occured.", but we will just redirect to current step of the flow.
>> Example:
>> a) User was redirected from the application to OIDC
>> AuthorizationEndpoint request. Login page is shown
>> b) User confirmed invalid username and password with POST request. Login
>> form with error page "Invalid password" is shown
>> c) User confirmed valid username and password with POST request. TOTP
>> page is shown.
>> d) User press back-button. Now he will see again the page with
>> username/password form.
>> e) User press F5. The POST request will be re-sent, but it will use
>> previous "code", which is outdated now. So in this case, we will
>> redirect to the current execution and TOTP form will be shown. No
>> re-submission of username/password form will happen.
>> In case 3, the username/password form will be shown again, but user
>> won't be able to resubmit it.
>> In shortcut: With 2 and 3, users will never see the browser page "Web
>> page is expired" or Keycloak "Error occured. Go back to the
>> application". With 2, there is additional GET request needed. With 3,
>> the back-button may show the authentication forms, which user already
>> successfully confirmed, but he won't be able to re-submit them. Is it
>> bad regarding usability? To me, it looks better than showing "Web page
>> is expired".
>> So my preference is 3,2,1. WDYT? Any other options?
>> Marek
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