PHP Write Xor Execute
A PHP extension to block execution of writable files. PHP Write Xor Execute (PWXE in short) will stop with a fatal error on execution (also through include and require) of any file which is either writable or owned by the current user.
Write XOR Execute is a concept used by operating systems to ensure that arbitrary data is not executed. This feature (although for files instead of memory blocks) is applied here.
Many exploits work through uploaded or overwritten PHP scripts. This extension blocks that attack vector.
Get the binary with the following commands:
phpize ./configure make
Install it (requires root privileges):
sudo make install
You will have to restart Apache for the changes to take effect.
The extension can be enabled / disabled with the pwxe.filter (admin) flag. (It is enabled by default).