ServerBuddies Support Blog

Increasing PHP security php functions

dl — Loads a PHP extension at runtime
This function is required for loading ionCube on the fly. However if you have a popular sites using ionCube then the better way is to load it from php.ini anyway. Not only because of speed increase, also you would be in control of ionCube versions so you can make sure that they match with your PHP versions.

exec — Execute an external program
This function is required for XCart and spellcheck feature of Horde. There is no good thing about letting this function work. You could perhaps use safe_mode to designate a safebin environment where you let users to execute only the binaries you allow.

fsockopen — Open Internet or Unix domain socket connection
This function is unfortunately required for Virtuemart paypal module. Thus removed from the example above. You can add it if you are sure that it wont break anything in your system.

Some times we get the following errors Fatal error: Allowed memory size of 123456 bytes exhausted

Php is setup is to limit memory usage per process. If we require more, this limit can be increased.

Edit

and set:

to a higher value, like 20M. Save, exit, then restart apache.

Source: http://directadmin.com/