Yii2的XSS攻擊防范策略分析

本文實例講述了Yii2的XSS攻擊防范策略。分享給大家供大家參考，具體如下：

XSS 漏洞修復

原則：　不相信客戶輸入的數據
注意: 攻擊代碼不一定在<script></script>中

① 將重要的cookie標記為http only, 這樣的話Javascript 中的document.cookie語句就不能獲取到cookie了.
② 只允許用戶輸入我們期望的數據。 例如：　年齡的textbox中，只允許用戶輸入數字。 而數字之外的字符都過濾掉。
③ 對數據進行Html Encode 處理
④ 過濾或移除特殊的Html標簽， 例如: script, iframe , < for <, > for >, " for
⑤ 過濾JavaScript 事件的標簽。例如 "onclick=", "onfocus" 等等。

Yii中的XSS防范

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

此方法的源碼：

/**
* 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 三者的區別：

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 &#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 &
" (double quote) becomes " when ENT_NOQUOTES is not set.
' (single quote) becomes ' (or ') 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='test'>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 'quote' is <b>bold</b>
echo htmlentities($str, ENT_QUOTES);
?>

urlencode

URL 編碼是為了符合url的規范。因為在標准的url規范中中文和很多的字符是不允許出現在url中的。

例如在baidu中搜索"測試漢字"。 URL會變成
http://www.baidu.com/s?wd=%B2%E2%CA%D4%BA%BA%D7%D6&rsv_bp=0&rsv_spt=3&inputT=7477

所謂URL編碼就是：　把所有非字母數字字符都將被替換成百分號（%）後跟兩位十六進制數，空格則編碼為加號（+）
　此字符串中除了 -_. 之外的所有非字母數字字符都將被替換成百分號（%）後跟兩位十六進制數，空格則編碼為加號（+）。此編碼與 WWW 表單 POST 數據的編碼方式是一樣的，同時與 application/x-www-form-urlencoded 的媒體類型編碼方式一樣。由於歷史原因，此編碼在將空格編碼為加號（+）方面與 RFC1738 編碼（參見 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) . '">';
?>

更多關於Yii相關內容感興趣的讀者可查看本站專題：《Yii框架入門及常用技巧總結》、《php優秀開發框架總結》、《smarty模板入門基礎教程》、《php面向對象程序設計入門教程》、《php字符串(string)用法總結》、《php+mysql數據庫操作入門教程》及《php常見數據庫操作技巧匯總》

希望本文所述對大家基於Yii框架的PHP程序設計有所幫助。