You should install this package in your Guest OS for X11 session.
-%package -n lightdm-vbox-greeter
+%package -n lightdm-greeter-vbox
Summary: VirtualBox greeter for lightdm
Group: Themes
URL: http://www.virtualbox.org/manual/ch09.html#autologon_unix_lightdm
Requires: lightdm >= 1.0.1
Provides: lightdm-greeter
-%description -n lightdm-vbox-greeter
+%description -n lightdm-greeter-vbox
VirtualBox greeter for LightDM.
%package -n pam-pam_vbox
%attr(755,root,root) %{_libdir}/%{pname}/additions/vboxadd-x11
%if %{with lightdm}
-%files -n lightdm-vbox-greeter
+%files -n lightdm-greeter-vbox
%defattr(644,root,root,755)
%attr(755,root,root) %{_sbindir}/vbox-greeter
%{_datadir}/xgreeters/vbox-greeter.desktop