I'm trying to find this movie about a girl who's sister went camping with her friends and she haven't came back home for a long time so her big sister went and looked for her but she couldn't find her where they camped at. They found a prison so they went in and looked in there but they found some of her friends dead and a sign on the wall, if you stare at that sign you'll turn into some kind of zombie.

The 8th Plague (http://www.imdb.com/title/tt0479219/)