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

1	`<?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 NameDescription
ENT_COMPATWill convert double-quotes and leave single-quotes alone.
ENT_QUOTESWill convert both double and single quotes.
ENT_NOQUOTESWill leave both double and single quotes unconverted.
ENT_IGNORESilently discard invalid code unit sequences instead of returning an empty string. Using this flag is discouraged as it » may have security implications.
ENT_SUBSTITUTEReplace invalid code unit sequences with a Unicode Replacement Character U+FFFD (UTF-8) or &#FFFD; (otherwise) instead of returning an empty string.
ENT_DISALLOWEDReplace 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_HTML401Handle code as HTML 4.01.
ENT_XML1Handle code as XML 1.
ENT_XHTMLHandle code as XHTML.
ENT_HTML5Handle code as HTML 5.

htmlspecialchars

Convert special characters to HTML entities