I've read up on the topic of C99 shell, and I can assure you I have not uploaded anything of the sort. The only thing close to that was a small admin panel that I use to edit site content. So, apparently I've uploaded a PHP file that allows me to change anything on the server. I didn't even know PHP could do it, or that something like that existed.
What I'm most concerned about, is that someone may have uploaded the C99 shell onto my website without me knowing. Can someone clear this up for me? I'm worried that I may be under fire for something I didn't do or even know about.
Thanks for your help.