Yii2的XSS攻击防范策略分析


            本文实例讲述了Yii2的XSS攻击防范策略。分享给大家供大家参考，具体如下：

XSS 漏洞修复

原则：　不相信客户输入的数据

注意: 攻击代码不一定在<script></script>中

① 将重要的cookie标记为http only, 这样的话Javascript 中的document.cookie语句就不能获取到cookie了.

② 只允许用户输入我们期望的数据。 例如：　年龄的textbox中，只允许用户输入数字。 而数字之外的字符都过滤掉。

③ 对数据进行Html Encode 处理

④ 过滤或移除特殊的Html标签， 例如: script, iframe , < for <, > for >, &quot for

⑤ 过滤JavaScript 事件的标签。例如 "onclick=", "onfocus" 等等。

Yii中的XSS防范





<?php echo CHtml::encode($user->name) ?>







此方法的源码：





/**

* Encodes special characters into HTML entities.

* The [[\yii\base\Application::charset|application charset]] will be used for encoding.

* @param string $content the content to be encoded

* @param boolean $doubleEncode whether to encode HTML entities in `$content`. If false,

* HTML entities in `$content` will not be further encoded.

* @return string the encoded content

* @see decode()

* @see http://www.php.net/manual/en/function.htmlspecialchars.php

*/

public static function encode($content, $doubleEncode = true)

{

  return htmlspecialchars($content, ENT_QUOTES | ENT_SUBSTITUTE, Yii::$app->charset, $doubleEncode);

}







htmlspecialchars & htmlentities & urlencode 三者的区别：

http://php.net/manual/zh/function.htmlspecialchars.php

http://php.net/manual/zh/function.htmlentities.php

http://cn2.php.net/manual/zh/function.urlencode.php

Available flags constants

Constant Name Description

ENT_COMPAT Will convert double-quotes and leave single-quotes alone.

ENT_QUOTES Will convert both double and single quotes.

ENT_NOQUOTES Will leave both double and single quotes unconverted.

ENT_IGNORE Silently discard invalid code unit sequences instead of returning an empty string. Using this flag is discouraged as it &raquo; may have security implications.

ENT_SUBSTITUTE Replace invalid code unit sequences with a Unicode Replacement Character U+FFFD (UTF-8) or &#FFFD; (otherwise) instead of returning an empty string.

ENT_DISALLOWED Replace invalid code points for the given document type with a Unicode Replacement Character U+FFFD (UTF-8) or &#FFFD; (otherwise) instead of leaving them as is. This may be useful, for instance, to ensure the well-formedness of XML documents with embedded external content.

ENT_HTML401 Handle code as HTML 4.01.

ENT_XML1 Handle code as XML 1.

ENT_XHTML Handle code as XHTML.

ENT_HTML5 Handle code as HTML 5.

htmlspecialchars

Convert special characters to HTML entities





string htmlspecialchars ( 

      string $string 

      [, int $flags = ENT_COMPAT | ENT_HTML401 

      [, string $encoding = ini_get("default_charset") 

      [, bool $double_encode = true ]

    ]

  ] 

)







The translations performed are:

& (ampersand) becomes &amp;

" (double quote) becomes &quot; when ENT_NOQUOTES is not set.

' (single quote) becomes &#039; (or &apos;) only when ENT_QUOTES is set.

< (less than) becomes <

> (greater than) becomes >





<?php

$new = htmlspecialchars("<a href='test'>Test</a>", ENT_QUOTES);

echo $new; // <a href=&#039;test&#039;>Test</a>

?>







htmlentities

Convert all applicable characters to HTML entities





string htmlentities ( 

      string $string 

      [, int $flags = ENT_COMPAT | ENT_HTML401 

      [, string $encoding = ini_get("default_charset") 

      [, bool $double_encode = true ]

    ]

  ] 

)











<?php

$str = "A 'quote' is <b>bold</b>";

// Outputs: A 'quote' is <b>bold</b>

echo htmlentities($str);

// Outputs: A &#039;quote&#039; is <b>bold</b>

echo htmlentities($str, ENT_QUOTES);

?>







urlencode

URL 编码是为了符合url的规范。因为在标准的url规范中中文和很多的字符是不允许出现在url中的。

例如在baidu中搜索"测试汉字"。 URL会变成

http://www.baidu.com/s?wd=%B2%E2%CA%D4%BA%BA%D7%D6&rsv_bp=0&rsv_spt=3&inputT=7477

所谓URL编码就是：　把所有非字母数字字符都将被替换成百分号（%）后跟两位十六进制数，空格则编码为加号（+）

　此字符串中除了 -_. 之外的所有非字母数字字符都将被替换成百分号（%）后跟两位十六进制数，空格则编码为加号（+）。此编码与 WWW 表单 POST 数据的编码方式是一样的，同时与 application/x-www-form-urlencoded 的媒体类型编码方式一样。由于历史原因，此编码在将空格编码为加号（+）方面与 RFC1738 编码（参见 rawurlencode()）不同。





<?php

echo '<a href="mycgi?foo=', urlencode($userinput), '">';

?>











<?php

$query_string = 'foo=' . urlencode($foo) . '&bar=' . urlencode($bar);

echo '<a href="mycgi?' . htmlentities($query_string) . '">';

?>







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