The website GraalDepot is the main source of Graphic stealing. The people that run that website use a data reading tool such as iFile to rip the files straight from the game, since they become cached on your device whenever you come across them in game.

The sad thing is that it is allowed for people to use other peoples graphics without their permission. As long as it has been uploaded on Graal it is property of Graal and no longer yours.