We are using SSO with siteminder to login to Tridion CMS. When ever a user tries to login the siteminder agent redirects him to login page. On providing credentials, they are validated by a policy server and on successful validation the user is redirected to cms dashboard. The issue is that even if the user exist in policy server but do not exist in Tridion CMS, he is able to log in to CMS. But in user name it displays NT AUTHORITY\IUSR where as I am not using impersonation anywhere (earlier this user was in impersonation but removed later). Is there any service which I forgot to restart after removing the impersonation user(Though I have restarted com+ and iisreset).
Whenever anonymous authentication is enabled IIS takes NT Authority\IUSR as logged in user. Also in web.config we comment the lines when configuring SSO. I am not able to understand when does the CMS deny user when implemented with SSO. In my case the user exist in SSO policy server but do not exist in CMS.