PHP清理跨站XSS xss_clean 函數 整理自codeigniter Security

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PHP清理跨站XSS xss_clean 函數 整理自codeigniter Security

由Security Class 改編成函數xss_clean 單檔案直接調用。BY吠品。

//來自codeigniter 清理跨站XSS xss_clean//Security Class 改編成函數function remove_invisible_characters($str, $url_encoded = TRUE){    $non_displayables = array();    if ($url_encoded) {        $non_displayables[] = ‘/%0[0-8bcef]/‘;        $non_displayables[] = ‘/%1[0-9a-f]/‘;    }    $non_displayables[] = ‘/[\\x00-\\x08\\x0B\\x0C\\x0E-\\x1F\\x7F]+/S‘;    do {        $str = preg_replace($non_displayables, ‘‘, $str, -1, $count);    } while ($count);    return $str;}function _convert_attribute($match){return str_replace(array(‘>‘, ‘<‘, ‘\\‘), array(‘>‘, ‘<‘, ‘\\\\‘), $match[0]);}function _decode_entity($match){$str = $match[0];if (stristr($str, ‘&‘) === FALSE){return $str;}$str = html_entity_decode($str, ENT_COMPAT, ‘UTF-8‘);$str = preg_replace(‘~&#x(0*[0-9a-f]{2,5})~ei‘, ‘chr(hexdec("\\1"))‘, $str);return preg_replace(‘~&#([0-9]{2,4})~e‘, ‘chr(\\1)‘, $str);}function _compact_exploded_words($matches){return preg_replace(‘/\s+/s‘, ‘‘, $matches[1]).$matches[2];}function _filter_attributes($str){$out = ‘‘;if (preg_match_all(‘#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is‘, $str, $matches)){foreach ($matches[0] as $match){$out .= preg_replace("#/\*.*?\*/#s", ‘‘, $match);}}return $out;}function _js_link_removal($match){return str_replace($match[1],preg_replace(‘#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si‘,‘‘,_filter_attributes(str_replace(array(‘<‘, ‘>‘), ‘‘, $match[1]))),$match[0]);}function _js_img_removal($match){return str_replace($match[1],preg_replace(‘#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si‘,‘‘,_filter_attributes(str_replace(array(‘<‘, ‘>‘), ‘‘, $match[1]))),$match[0]);}function _sanitize_naughty_html($matches){// encode opening brace$str = ‘<‘.$matches[1].$matches[2].$matches[3];// encode captured opening or closing brace to prevent recursive vectors$str .= str_replace(array(‘>‘, ‘<‘), array(‘>‘, ‘<‘),$matches[4]);return $str;}//調用這個函數//from http://www.cnblogs.com/osfipin/function xss_clean($str, $is_image = FALSE){/* * Is the string an array? * */if (is_array($str)){while (list($key) = each($str)){$str[$key] = xss_clean($str[$key]);}return $str;}$str = remove_invisible_characters($str);// Validate Entities in URLs$hash = md5(time() + mt_rand(0, 1999999999));$str = preg_replace(‘|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-]+)|i‘, $hash."\\1=\\2", $str);$str = preg_replace(‘#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i‘, "\\1;\\2", $str);$str = preg_replace(‘#(&\#x?)([0-9A-F]+);?#i‘,"\\1\\2;",$str);$str = str_replace($hash, ‘&‘, $str);$str = rawurldecode($str);/* * Convert character entities to ASCII * * This permits our tests below to work reliably. * We only convert entities that are within tags since * these are the ones that will pose security problems. * */$str = preg_replace_callback("/[a-z]+=([\‘\"]).*?\\1/si",  ‘_convert_attribute‘, $str);$str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si",  ‘_decode_entity‘, $str);/* * Remove Invisible Characters Again! */$str = remove_invisible_characters($str);/* * Convert all tabs to spaces * * This prevents strings like this: javascript * NOTE: we deal with spaces between characters later. * NOTE: preg_replace was found to be amazingly slow here on * large blocks of data, so we use str_replace. */if (strpos($str, "\t") !== FALSE){$str = str_replace("\t", ‘ ‘, $str);}/* * Capture converted string for later comparison */$converted_string = $str;// Remove Strings that are never allowed$_never_allowed_str = array(‘document.cookie‘=> ‘[removed]‘,‘document.write‘=> ‘[removed]‘,‘.parentNode‘=> ‘[removed]‘,‘.innerHTML‘=> ‘[removed]‘,‘window.location‘=> ‘[removed]‘,‘-moz-binding‘=> ‘[removed]‘,‘<!--‘=> ‘<!--‘,‘-->‘=> ‘-->‘,‘<![CDATA[‘=> ‘<![CDATA[‘,‘<comment>‘=> ‘<comment>‘);$str = str_replace(array_keys($_never_allowed_str), $_never_allowed_str, $str);$_never_allowed_regex = array(‘javascript\s*:‘,‘expression\s*(\(|&\#40;)‘, // CSS and IE‘vbscript\s*:‘, // IE, surprise!‘Redirect\s+302‘,"([\"‘])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?");foreach ($_never_allowed_regex as $regex){$str = preg_replace(‘#‘.$regex.‘#is‘, ‘[removed]‘, $str);}/* * Makes PHP tags safe * * Note: XML tags are inadvertently replaced too: * * <?xml * * But it doesn‘t seem to pose a problem. */if ($is_image === TRUE){// Images have a tendency to have the PHP short opening and// closing tags every so often so we skip those and only// do the long opening tags.$str = preg_replace(‘/<\?(php)/i‘, "<?\\1", $str);}else{$str = str_replace(array(‘<?‘, ‘?‘.‘>‘),  array(‘<?‘, ‘?>‘), $str);}/* * Compact any exploded words * * This corrects words like:  j a v a s c r i p t * These words are compacted back to their correct state. */$words = array(‘javascript‘, ‘expression‘, ‘vbscript‘, ‘script‘, ‘base64‘,‘applet‘, ‘alert‘, ‘document‘, ‘write‘, ‘cookie‘, ‘window‘);foreach ($words as $word){$temp = ‘‘;for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++){$temp .= substr($word, $i, 1)."\s*";}// We only want to do this when it is followed by a non-word character// That way valid stuff like "dealer to" does not become "dealerto"$str = preg_replace_callback(‘#(‘.substr($temp, 0, -3).‘)(\W)#is‘, ‘_compact_exploded_words‘, $str);}/* * Remove disallowed Javascript in links or img tags * We used to do some version comparisons and use of stripos for PHP5, * but it is dog slow compared to these simplified non-capturing * preg_match(), especially if the pattern exists in the string */do{$original = $str;if (preg_match("/<a/i", $str)){$str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", ‘_js_link_removal‘, $str);}if (preg_match("/<img/i", $str)){$str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", ‘_js_img_removal‘, $str);}if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str)){$str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", ‘[removed]‘, $str);}}while($original != $str);unset($original);// Remove evil attributes such as style, onclick and xmlns// All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns$evil_attributes = array(‘on\w*‘, ‘style‘, ‘xmlns‘, ‘formaction‘);if ($is_image === TRUE){/* * Adobe Photoshop puts XML metadata into JFIF images,  * including namespacing, so we have to allow this for images. */unset($evil_attributes[array_search(‘xmlns‘, $evil_attributes)]);}do {$count = 0;$attribs = array();// find occurrences of illegal attribute strings with quotes (042 and 047 are octal quotes)preg_match_all(‘/(‘.implode(‘|‘, $evil_attributes).‘)\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is‘, $str, $matches, PREG_SET_ORDER);foreach ($matches as $attr){$attribs[] = preg_quote($attr[0], ‘/‘);}// find occurrences of illegal attribute strings without quotespreg_match_all(‘/(‘.implode(‘|‘, $evil_attributes).‘)\s*=\s*([^\s>]*)/is‘, $str, $matches, PREG_SET_ORDER);foreach ($matches as $attr){$attribs[] = preg_quote($attr[0], ‘/‘);}// replace illegal attribute strings that are inside an html tagif (count($attribs) > 0){$str = preg_replace(‘/(<?)(\/?[^><]+?)([^A-Za-z<>\-])(.*?)(‘.implode(‘|‘, $attribs).‘)(.*?)([\s><]?)([><]*)/i‘, ‘$1$2 $4$6$7$8‘, $str, -1, $count);}} while ($count);/* * Sanitize naughty HTML elements * * If a tag containing any of the words in the list * below is found, the tag gets converted to entities. * * So this: <blink> * Becomes: <blink> */$naughty = ‘alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss‘;$str = preg_replace_callback(‘#<(/*\s*)(‘.$naughty.‘)([^><]*)([><]*)#is‘,‘_sanitize_naughty_html‘, $str);/* * Sanitize naughty scripting elements * * Similar to above, only instead of looking for * tags it looks for PHP and JavaScript commands * that are disallowed.  Rather than removing the * code, it simply converts the parenthesis to entities * rendering the code un-executable. * * For example:eval(‘some code‘) * Becomes:eval(‘some code‘) */$str = preg_replace(‘#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si‘, "\\1\\2(\\3)", $str);// Final clean up// This adds a bit of extra precaution in case// something got through the above filters$str = str_replace(array_keys($_never_allowed_str), $_never_allowed_str, $str);foreach ($_never_allowed_regex as $regex){$str = preg_replace(‘#‘.$regex.‘#is‘, ‘[removed]‘, $str);}/* * Images are Handled in a Special Way * - Essentially, we want to know that after all of the character * conversion is done whether any unwanted, likely XSS, code was found. * If not, we return TRUE, as the image is clean. * However, if the string post-conversion does not matched the * string post-removal of XSS, then it fails, as there was unwanted XSS * code found and removed/changed during processing. */if ($is_image === TRUE){return ($str == $converted_string) ? TRUE: FALSE;}return $str;}///測試function show($r){echo $r;echo ‘<br/>‘;echo xss_clean($r);echo ‘<br/><br/>‘;}show(‘%3Cscript%3Ealert(’XSS’)%3C/script%3E‘);show(‘%3c/a%3e%3cscript%3ealert(%22xss%22)%3c/script%3e‘);show(‘<IMG SRC="javascript:alert(’XSS’);">‘);show(‘<STYLE type="text/css">BODY{background:url("javascript:alert(’XSS’)")}</STYLE>‘);

　　

可以測試下效果如何

 

PHP清理跨站XSS xss_clean 函數 整理自codeigniter Security