UO Second Age

If you were polymorphed and had not stolen anything or comitted any other action that would flag you grey (though you are grey by default because of the spell) and were attacked, could you fight back and steal possibly even kill your attacker without receiving a murder count?

yes. this is called noto pking. it was very common for people to do this during t2a. a friend of mine on chessy had a character named "an ogre" and would polymorph into an ogre. when newbs would attack him, he would go all tank mage on their ass.