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XSS Clean Function for PHP
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<?php | |
public static function xss_clean($data) | |
{ | |
// Fix &entity\n; | |
$data = str_replace(array('&', '<', '>'), array('&amp;', '&lt;', '&gt;'), $data); | |
$data = preg_replace('/(&#*\w+)[\x00-\x20]+;/u', '$1;', $data); | |
$data = preg_replace('/(&#x*[0-9A-F]+);*/iu', '$1;', $data); | |
$data = html_entity_decode($data, ENT_COMPAT, 'UTF-8'); | |
// Remove any attribute starting with "on" or xmlns | |
$data = preg_replace('#(<[^>]+?[\x00-\x20"\'])(?:on|xmlns)[^>]*+>#iu', '$1>', $data); | |
// Remove javascript: and vbscript: protocols | |
$data = preg_replace('#([a-z]*)[\x00-\x20]*=[\x00-\x20]*([`\'"]*)[\x00-\x20]*j[\x00-\x20]*a[\x00-\x20]*v[\x00-\x20]*a[\x00-\x20]*s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:#iu', '$1=$2nojavascript...', $data); | |
$data = preg_replace('#([a-z]*)[\x00-\x20]*=([\'"]*)[\x00-\x20]*v[\x00-\x20]*b[\x00-\x20]*s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:#iu', '$1=$2novbscript...', $data); | |
$data = preg_replace('#([a-z]*)[\x00-\x20]*=([\'"]*)[\x00-\x20]*-moz-binding[\x00-\x20]*:#u', '$1=$2nomozbinding...', $data); | |
// Only works in IE: <span style="width: expression(alert('Ping!'));"></span> | |
$data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?expression[\x00-\x20]*\([^>]*+>#i', '$1>', $data); | |
$data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?behaviour[\x00-\x20]*\([^>]*+>#i', '$1>', $data); | |
$data = preg_replace('#(<[^>]+?)style[\x00-\x20]*=[\x00-\x20]*[`\'"]*.*?s[\x00-\x20]*c[\x00-\x20]*r[\x00-\x20]*i[\x00-\x20]*p[\x00-\x20]*t[\x00-\x20]*:*[^>]*+>#iu', '$1>', $data); | |
// Remove namespaced elements (we do not need them) | |
$data = preg_replace('#</*\w+:\w[^>]*+>#i', '', $data); | |
do { | |
// Remove really unwanted tags | |
$old_data = $data; | |
$data = preg_replace('#</*(?:applet|b(?:ase|gsound|link)|embed|frame(?:set)?|i(?:frame|layer)|l(?:ayer|ink)|meta|object|s(?:cript|tyle)|title|xml)[^>]*+>#i', '', $data); | |
} while ($old_data !== $data); | |
// we are done... | |
return $data; | |
} |
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