PHP is an incredibly popular language for creating dynamic web applications — websites such as Facebook are built on it. This can be attributed to many reasons; it is easy to learn, easy to install and does not require the user to compile code. An unfortunate side effect of the ease of development with PHP is a tendency to ignore security during the development process.
In this post, I will discuss some of the ways to make your PHP apps more secure. I will go through creating a PHP web app that connects to a MySQL back end database. The application will be a simple address book. The approach I will take to secure the PHP code is one of layered security. There is no sure fire quick method of blocking all attacks, but using the layered security approach we severely limit our exposure.