/usr/share/unity-greeter/custom_fvwm-crystal_badge.png is in unity-greeter-badges 0.4-0ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/unity-greeter/custom_fvwm_badge.png
/usr/share/unity-greeter/custom_fvwm_badge.png