my advice to you is to realize it was done under circumstances that they normally would not have occurred. Then as far as who did it to her, does it really matter? you can not change that it was done, and you can not change it if she wanted it to happen or not. I would say that you should talk to her about it, but more in the way that "you know how much I think of you and to see this happen to you really bothers me", and then let her know that you care and to see her doing this stuff makes her look bad and you want the best for her.