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 >, " 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 » may have security implications.
ENT_SUBSTITUTE Replace invalid code unit sequences with a Unicode Replacement Character U+FFFD (UTF-8) or &#