php xss過濾

XSS又叫CSS (Cross Site Script) ，跨站指令碼攻擊。它指的是惡意攻擊者往Web頁面裡插入惡意html代碼，當使用者瀏覽該頁之時，嵌入其中Web裡面的html代碼會被執行，進而達到某些人的攻擊目的。

下面是thinkphp裡面的一段代碼，用於過濾xss

ThinkPHP\Code\ThinkPHP\Common\extend.php

               // note that you have to handle splits with \n, \r, and \t later since they *are* allowed in some inputs           $val = preg_replace('/([\x00-\x08,\x0b-\x0c,\x0e-\x19])/', '', $val);                  // straight replacements, the user should never need these since they're normal characters           // this prevents like            $search = 'abcdefghijklmnopqrstuvwxyz';          $search .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';           $search .= '1234567890!@#$%^&*()';          $search .= '~`";:?+/={}[]-_|\'\\';          for ($i = 0; $i < strlen($search); $i++) {             // ;? matches the ;, which is optional             // 0{0,7} matches any padded zeros, which are optional and go up to 8 chars                    // @ @ search for the hex values             $val = preg_replace('/(&#[xX]0{0,8}'.dechex(ord($search[$i])).';?)/i', $search[$i], $val); // with a ;             // @ @ 0{0,7} matches '0' zero to seven times              $val = preg_replace('/(?{0,8}'.ord($search[$i]).';?)/', $search[$i], $val); // with a ;          }                 // now the only remaining whitespace attacks are \t, \n, and \r          $ra1 = Array('javascript', 'vbscript', 'expression', 'applet', 'meta', 'xml', 'blink', 'link', 'style', 'script', 'embed', 'object', 'iframe', 'frame', 'frameset', 'ilayer', 'layer', 'bgsound', 'title', 'base');          $ra2 = Array('onabort', 'onactivate', 'onafterprint', 'onafterupdate', 'onbeforeactivate', 'onbeforecopy', 'onbeforecut', 'onbeforedeactivate', 'onbeforeeditfocus', 'onbeforepaste', 'onbeforeprint', 'onbeforeunload', 'onbeforeupdate', 'onblur', 'onbounce', 'oncellchange', 'onchange', 'onclick', 'oncontextmenu', 'oncontrolselect', 'oncopy', 'oncut', 'ondataavailable', 'ondatasetchanged', 'ondatasetcomplete', 'ondblclick', 'ondeactivate', 'ondrag', 'ondragend', 'ondragenter', 'ondragleave', 'ondragover', 'ondragstart', 'ondrop', 'onerror', 'onerrorupdate', 'onfilterchange', 'onfinish', 'onfocus', 'onfocusin', 'onfocusout', 'onhelp', 'onkeydown', 'onkeypress', 'onkeyup', 'onlayoutcomplete', 'onload', 'onlosecapture', 'onmousedown', 'onmouseenter', 'onmouseleave', 'onmousemove', 'onmouseout', 'onmouseover', 'onmouseup', 'onmousewheel', 'onmove', 'onmoveend', 'onmovestart', 'onpaste', 'onpropertychange', 'onreadystatechange', 'onreset', 'onresize', 'onresizeend', 'onresizestart', 'onrowenter', 'onrowexit', 'onrowsdelete', 'onrowsinserted', 'onscroll', 'onselect', 'onselectionchange', 'onselectstart', 'onstart', 'onstop', 'onsubmit', 'onunload');          $ra = array_merge($ra1, $ra2);                 $found = true; // keep replacing as long as the previous round replaced something          while ($found == true) {             $val_before = $val;             for ($i = 0; $i < sizeof($ra); $i++) {                $pattern = '/';                for ($j = 0; $j < strlen($ra[$i]); $j++) {                   if ($j > 0) {                      $pattern .= '(';                       $pattern .= '(&#[xX]0{0,8}([9ab]);)';                      $pattern .= '|';                       $pattern .= '|(?{0,8}([9|10|13]);)';                      $pattern .= ')*';                   }                   $pattern .= $ra[$i][$j];                }                $pattern .= '/i';                 $replacement = substr($ra[$i], 0, 2).''.substr($ra[$i], 2); // add in <> to nerf the tag                 $val = preg_replace($pattern, $replacement, $val); // filter out the hex tags                 if ($val_before == $val) {                    // no replacements were made, so exit the loop                    $found = false;                 }              }           }           return $val;        }      //測試一下效果      //echo RemoveXSS("") ;      ?>  

此外還有一個工具：HTML Purifier，比上面的文檔效率高一倍，欲知後事如何，且聽下回分解。

