Preventing cross-site-scripting (XSS) vulnerability
Recently i came across a report at xssed.com, about ebharatjobs.com being vulnerable to cross site scripting (XSS). That report was filed way back in 2009, and we have already fixed that when we upgraded www.ebharatjobs.com in 2010.
I wanted to share the code we used to check the input from users to possibly prevent XSS vulnerability.
// cross-site-scripting (XSS) vulnerability
$q = $_GET["q"];
//remove the script tag and its contents
$q = preg_replace('/]*>([\s\S]*?)<\/script[^>]*>/', '', $q);
// remove any special chars - if you need them, then you can skip this step.
$q = preg_replace('/[^a-zA-Z-,\s]/', '', $q);
This will ensure you minimize the risk.
Please do share your thoughts.