~~~ function xss_clean($data) { $datadirty = $data; // Fix &entity\n; $data = str_replace(array('&amp;', '&lt;', '&gt;'), array('&amp;amp;', '&amp;lt;', '&amp;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 !== $data); // we are done... // if($datadirty !== $data) debugLog("string cleaned: removed ". (strlen($datadirty) - strlen($data)) .' chars'); return $data; } ~~~