Oracle remote OS authentication, security risks with domain users

What security risks can be with domain users?

create user "OPS$KAUSERNAME" identified externally.

grant create session to "OPS$KAMARIK";

Then MARIK that is in KA domain, can logon to the database without password.

I wander to know if oracle checks that the user is a really domain user?

For example is there a risk that somebody with the computer name LB and username MARIK can connect to the database , even it is not a domain user?