Any local user can call CreateTransientDisplay on the org.gnome.DisplayManager.LocalDisplayFactory interface which results in a new X session. Beyond that this will annoy the hell out of whoever is on the local machine I suspect that a loop that keeps sending the message can be an effective DOS.
Created attachment 322103 [details] example "exploit"
So at a minimum we should modify the dbus security policy in /etc/dbus-1/system.d to only allow at_console users to run it, but really we should be using policykit to levy access.
Is this interface used to spawn another local session when some user is already logged-in in X? If so, restricting this to console users only sounds good. I'm not sure how PolicyKit is expected to be used here.
I at least have no idea at all as to what is using this interface. Probably just fast user switching but you never know. I am not sure that I want my users to be able to start an unlimited amount of X servers even if they are in the console to tell the truth but this is a different story I guess.
This bug appears to have been reported against 'rawhide' during the Fedora 10 development cycle. Changing version to '10'. More information and reason for this action is here: http://fedoraproject.org/wiki/BugZappers/HouseKeeping
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Fedora 10 changed to end-of-life (EOL) status on 2009-12-17. Fedora 10 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. Thank you for reporting this bug and we are sorry it could not be fixed.