I created a few ftp folders for other people to upload files, and the ftp client prevents them from accessing folders and files outside of their ftp folder during an ftp session. This is expected and good. However... they can still upload a php file and run commands from the php file to view files outside of their ftp folder. They can even delete folders outside of the ftp folder by uploading a php file and running a bash command using the php exec function.
How can I prevent this? I want to have ftp folders which limit access to that folder and its subfolders only. Does cPanel have a way to configure this security? Can I make some simple changes to file or folder permissions to accomplish this?