Hackers are focusing on vulnerabilities in the PHP web application development platform threatening 80% websites in the world, including many big website i.e. Facebook and Wikipedia. PHP has several predefined variables that are called SuperGlobals i.e. POST, GET, COOKIES, FILES etc.
Imperva Releases Hacker Intelligence Initiative Report, particularly concerned about two vulnerabilities
Source: Web Application Security : PHP SuperGlobal Variables are vulnerable to Hackers