Ok, so the problem I'm having with images is quite complicated. Basically a lot of scripts in this game "do stuff". For example, the script gangs8_1.php when navigated to will make you leave your current gang (this is what I did with my proof of concept exploit). In order to link someone to this script you need to first steal their session ID and then redirect them to the relevant URL, very easy to do if we allow IMG tags on the forums.

My fix for this is to implement code that upon arrival at gangs8_1.php (and the hundred or so other scripts like it) checks the page you came from. So if you did not come from the page leading to it, then it will error. However, this error would also pop up if you used the back button on your browser before clicking a link to do something.

I don't know how often players use the back button when playing my game so I have no idea how inconvenient this fix is going to become. All I can do is implement it and see, this will be done once all the scripts are updated.