Ctrl+Alt+Del is the path to the Secure attention key on Windows computers.
Some of the answers on related questions imply it is possible to modify the this.
My thinking is that a password does not do you any good, if you can't get to the screen to enter it. If you changed the key combination required to access Winlogon and don't publish the change, would there be a measurable change in your system security?
Presumably it would be possible to send users of Ctrl+Alt+Del to a sandbox, and begin security containment activities. While users with the correct different combination go to the production system.