Yeah that's rough
Not that is matters much, but I did find it interesting reading this CNN report that says while the ARs were legally purchased they were modified to allow detachable magazines and one was modified to allow automatic fire.
http://www.cnn.com/2015/12/05/us/cal...inkId=19343369
Farook's neighbor, Enrique Marquez, was the person who purchased the rifles. It hasn't been revealed if he had prior knowledge of the attack.