Nothing new and in fact it's an extremely common hack to do a recursive find over the upper directory to see if there are any directories with the global write

Nothing new and in fact it's an extremely common hack to do a recursive find over the upper directory to see if there are any directories with the global write bit set, then drop a php file to get access to their file system. In general, you should never put anything on a shared server that you don't want to world to see.