A Piper Cub pilot reported they hand cranked the prop and the aircraft rolled uncontrolled striking the reporter and a hangar.

Narrative

I was hand propping the airplane and it cranked hard and lurched forward. It knocked me slightly off balance and started rolling. It did a u-turn and struck the wing and propeller into the side of a hangar. I had originally tried to prime and crank the airplane with the starter; but the battery was dead. I pulled the prop through; and primed the aircraft again before hand propping. The oil tank was hot because it was pre-heated. I have hand propped many airplanes; including this particular cub; and believe all of these things allowed the engine to crank with more force than normal on a cold day. I know many people also tie the tail down; in addition to a chock; but that is not possible on the pavement. In order to prevent this situation from occurring again; I can push the airplane to a location that does allow me to tie the airplane down; in addition to the wheel chock. I can also call someone to assist inside the airplane by making it a 2 person job when hand propping the airplane.