How to detect users who get access via SSO?

I don't believe there's an existing way to accomplish this, what requirement are you trying to fulfill?

The main idea was to prevent SSO users from changing their personal email addresses.
For that I have to do the next:
1) detect users who get access to the site via SSO
2) deny SSO users changing the private email addresses

I've found the way to detect sso user. We can use  "$core_v2_authentication.GetLastLoginType()".
If users get access to site via SSO the "$core_v2_authentication.GetLastLoginType()" will return SSO name. If users use login without SSO the "$core_v2_authentication.GetLastLoginType()" will return empty string.