PHP通用的XSS攻击过滤函数，Discuz系统中防止XSS漏洞攻击，过滤HTML危险标签属性的PHP函数

博主：飞鱼
发布时间：2023 年 03 月 11 日
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467字数
分类：代码片段

XSS攻击在最近很是流行，往往在某段代码里一不小心就会被人放上XSS攻击的代码，看到国外有人写上了函数，咱也偷偷懒，悄悄的贴上来。。。
原文如下：

> The goal of this function is to be a generic function that can be used to parse almost any input and render it XSS safe. For more information on actual XSS attacks, check out [http://ha.ckers.org/xss.html](http://ha.ckers.org/xss.html). Another excellent site is the [XSS Database](http://www.gnucitizen.org/xssdb/application.htm) which details each attack and how it works.
>

```php
<?php
function RemoveXSS($val) {
   // remove all non-printable characters. CR(0a) and LF(0b) and TAB(9) are allowed
   // this prevents some character re-spacing such as <javascript>
   // note that you have to handle splits with
,
, and    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 <IMG SRC=@avascript:alert('XSS')>
   $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
      $val = preg_replace('/(&#0{0,8}'.ord($search[$i]).';?)/', $search[$i], $val); // with a ;
   }
 
   // now the only remaining whitespace attacks are     ,
, and
 
   $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{0,8}([9|10|13]);)';
               $pattern .= ')*';
            }
            $pattern .= $ra[$i][$j];
         }
         $pattern .= '/i';
         $replacement = substr($ra[$i], 0, 2).'<x>'.substr($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;
}
?>
```

经过这样的过滤后，应该被攻击的机会会少上很多吧？试试看呢？

---

**Discuz系统中 防止XSS漏洞攻击，过滤HTML危险标签属性的PHP函数**

```php
function string_remove_xss($html) {
    preg_match_all("/\<([^\<]+)\>/is", $html, $ms);
 
    $searchs[] = '<';
    $replaces[] = '<';
    $searchs[] = '>';
    $replaces[] = '>';
 
    if ($ms[1]) {
        $allowtags = 'img|a|font|div|table|tbody|caption|tr|td|th|br|p|b|strong|i|u|em|span|ol|ul|li|blockquote';
        $ms[1] = array_unique($ms[1]);
        foreach ($ms[1] as $value) {
            $searchs[] = "<".$value.">";
 
            $value = str_replace('&', '_uch_tmp_str_', $value);
            $value = string_htmlspecialchars($value);
            $value = str_replace('_uch_tmp_str_', '&', $value);
 
            $value = str_replace(array('\\', '/*'), array('.', '/.'), $value);
            $skipkeys = 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','javascript','script','eval','behaviour','expression','style','class');
            $skipstr = implode('|', $skipkeys);
            $value = preg_replace(array("/($skipstr)/i"), '.', $value);
            if (!preg_match("/^[\/|\s]?($allowtags)(\s+|$)/is", $value)) {
                $value = '';
            }
            $replaces[] = empty($value) ? '' : "<" . str_replace('"', '"', $value) . ">";
        }
    }
    $html = str_replace($searchs, $replaces, $html);
 
    return $html;
}
 
function string_htmlspecialchars($string, $flags = null) {
    if (is_array($string)) {
        foreach ($string as $key => $val) {
            $string[$key] = string_htmlspecialchars($val, $flags);
        }
    } else {
        if ($flags === null) {
            $string = str_replace(array('&', '"', '<', '>'), array('&', '"', '<', '>'), $string);
            if (strpos($string, '&#') !== false) {
                $string = preg_replace('/&((#(\d{3,5}|x[a-fA-F0-9]{4}));)/', '&\\1', $string);
            }
        } else {
            if (PHP_VERSION < '5.4.0') {
                $string = htmlspecialchars($string, $flags);
            } else {
                if (!defined('CHARSET') || (strtolower(CHARSET) == 'utf-8')) {
                    $charset = 'UTF-8';
                } else {
                    $charset = 'ISO-8859-1';
                }
                $string = htmlspecialchars($string, $flags, $charset);
            }
        }
    }
 
    return $string;
}
```

最后修改：2023 年 03 月 11 日

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PHP通用的XSS攻击过滤函数，Discuz系统中防止XSS漏洞攻击，过滤HTML危险标签属性的PHP函数

飞鱼 • 2023 年 03 月 11 日

经过这样的过滤后，应该被攻击的机会会少上很多吧？试试看呢？

---

**Discuz系统中 防止XSS漏洞攻击，过滤HTML危险标签属性的PHP函数**

PHP通用的XSS攻击过滤函数，Discuz系统中防止XSS漏洞攻击，过滤HTML危险标签属性的PHP函数

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PHP通用的XSS攻击过滤函数，Discuz系统中防止XSS漏洞攻击，过滤HTML危险标签属性的PHP函数

发表评论 取消回复 使用cookie技术保留您的个人信息以便您下次快速评论，继续评论表示您已同意该条款

PHP通用的XSS攻击过滤函数，Discuz系统中 防止XSS漏洞攻击，过滤HTML危险标签属性的PHP函数

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使用cookie技术保留您的个人信息以便您下次快速评论，继续评论表示您已同意该条款

PHP通用的XSS攻击过滤函数，Discuz系统中防止XSS漏洞攻击，过滤HTML危险标签属性的PHP函数