friend, if you are really that paranoid why not buy a genuine licence (but even then you are NOT guaranteed no backdoors.) But look on a serious note. IF you are NOT sharing members personal bank details, fone numbers or any personal data you should be gud to go. I know friends who have used Xf 1.x.x to xf 2.2.x and never heard anyone yet complain, or say there is a backdoor. Download and try it on a localhost using something like XAMPP. Play around and test it out for yourself.i would like to know how i can be sure that nulled xenforo is safe and has no backdoors as i am very paranoid about my security