No passwords? Its pwnage time!
". My workplace does passwordless vnc too.."
Might want to look at UltraVNC (also free) then and enable the built in domain authentication. That way your users can get in provided they can remember their own passwords into their pc's.
Back in 2003, there was a virus out that used passwordless VNC's to spread. Once its inside your firewall, it was also kinda hard to stop at that point. This caused me to have to have to build a specific patch for a commercial product (that will go unnamed) to disable VNC if the install detected no password set. I'm flabbergasted that this is still occurring 11 years later...
Here is a forum posting from REALVNC:
(Paris, because she probably has passwordless VNC as well)