When we have accesses to protected resources by non-defined users in our User Directory, the browser becomes non-responsive and keep showing a white screen. We use IWA authentication, and we see many AuthAttempt entries in smaccess.log when this happens.
For the IWA use case, the Authentication is done by the IIS server. The Web Agent and Policy Server "trust" the IIS Authentication. After the Authentication process, the Web Agent and the Policy Server need to authorize the User to access the request. And as such, the Policy Server needs to find the User in the User Store. If the Policy Server doesn't find the User in the User Store, then the Policy Server cannot authorize the User. You'll see "Authentication Attempt" failed errors in smaccess.log. As such, the Policy Server will request the Web Agent to authenticate the User again. As the authentication is done by the IIS server, then the transaction enters in a loop. The Web Agent will trust the successful authentication from the IIS Server and the Web Agent will request the Policy Server to authorize the User.
Depending on the brower, this loop will continue until a number of times after which the browser will stop processing.
Web Agent on IIS
In this case, in order to avoid this loop, the solution would be to redirect user to a not authenticated page through redirect responses.
For example, if a redirect response is created in such way that when user is not authenticated Web Agent should redirect to http://server.com/notauthenticated.html. This shows that the particular user is not authenticated to access the page.
Create new rules with OnAuthReject and create a Webagent-onreject-redirect response. If user is not authenticated he will be then redirected to desired page avoiding the loop.