AppHash tries to address this by having something called a "hostile block" in a page. The hash is checked for everything BUT the hostile block, and the hostile

AppHash tries to address this by having something called a "hostile block" in a page. The hash is checked for everything BUT the hostile block, and the hostile block itself is checked to make sure it only contains static variable assignments. Yes, this is a fiddly bit of code - I'd love for people to see if they could break it.