I see a lot of requests for nonexistent php files on my website.  They tend to have a querystring like appserv_root=http://www.example.com, using domains with evil-looking php code.I am pretty confident that this is trying to make use of some php vulnerability or other.  So, I am curious:What vulnerability is this trying to make use of?How does one protect against this vulnerability?What in the site configuration would be changed if this vulnerability was successfully exploited?
What is the purpose of the appserv_root requests?
php;security
Looks like they're trying to do a remote file include attack. Looks like this is the vulnerability they are trying to exploit but I'm not 100% sure of it. I'm guessing you look safe if you're not using that application and/or have register_globals turned off (which you always should).