Only two files should be in your /forum folder:
index.php (which is basically just a redirector to ubbthreads.php)
ubbthreads.php
Well you could have a couple of other legit files
Such as
favicon
Robots.txt
.htaccess.
Just to name a few
But you should be already aware of them
Not part of stock install
palinode.php is for sure a stranger
