Secure the SYS connection from Windows OS Authentication

Hello,

  I have a database Oracle 10g installed under Windows 2008 Server. As we know, starting 10g, the database can be authenticated by OS. This means,

when an Administrator OS log in, he can simply use : SQLPLUS SYS/anypassword as SYSDBA and he will be connected to the database. Even he can

use SQLPLUS anyname/anypassword as SYSDBA and he will be logged in.

This can be limited by setting the AUTHENTICATION to NONE instead of NTS in SQLNET.ORA at the database Server level.

But what if the System Administrator knows this SQLNET.ORA , so he can change it and log in again.