Discuz! 7.1 & 7.2 远程代码执行漏洞

Discuz! 7.1 & 7.2

产生漏洞的$scriptlang数组在安装插件后已经初始化

Discuz！新版本7.1与7.2版本中的showmessage函数中eval中执行的参数未初始化，可以任意提交，从而可以执行任意PHP命令。

下面来分析下这个远程代码执行漏洞，这个问题真的很严重，可以直接写shell的：

一、漏洞来自showmessage函数：

function showmessage($message, $url_forward = ‘‘, $extra = ‘‘, $forwardtype = 0) {
     extract($GLOBALS, EXTR_SKIP);//危险的用法，未初始化的变量可以直接带进函数，直接导致了问题产生，from www.oldjun.com
     global $hookscriptmessage, $extrahead, $discuz_uid, $discuz_action, $debuginfo, $seccode, $seccodestatus, $fid, $tid, $charset, $show_message, $inajax, $_DCACHE, $advlist;
     define(‘CACHE_FORBIDDEN‘, TRUE);
     $hookscriptmessage = $show_message = $message;$messagehandle = 0;
     $msgforward = unserialize($_DCACHE[‘settings‘][‘msgforward‘]);
     $refreshtime = intval($msgforward[‘refreshtime‘]);
     $refreshtime = empty($forwardtype) ? $refreshtime : ($refreshtime ? $refreshtime : 3);
     $msgforward[‘refreshtime‘] = $refreshtime * 1000;
     $url_forward = empty($url_forward) ? ‘‘ : (empty($_DCOOKIE[‘sid‘]) && $transsidstatus ? transsid($url_forward) : $url_forward);
     $seccodecheck = $seccodestatus & 2;
     if($_DCACHE[‘settings‘][‘funcsiteid‘] && $_DCACHE[‘settings‘][‘funckey‘] && $funcstatinfo && !IS_ROBOT) {
         $statlogfile = DISCUZ_ROOT.‘./forumdata/funcstat.log‘;
         if($fp = @fopen($statlogfile, ‘a‘)) {
             @flock($fp, 2);
             if(is_array($funcstatinfo)) {
                 $funcstatinfo = array_unique($funcstatinfo);
                 foreach($funcstatinfo as $funcinfo) {
                     fwrite($fp, funcstat_query($funcinfo, $message)."\n");
                 }
             } else {
                 fwrite($fp, funcstat_query($funcstatinfo, $message)."\n");
             }
             fclose($fp);
             $funcstatinfo = $GLOBALS[‘funcstatinfo‘] = ‘‘;
         }
     }

     if(!defined(‘STAT_DISABLED‘) && STAT_ID > 0 && !IS_ROBOT) {
         write_statlog($message);
     }

     if($url_forward && (!empty($quickforward) || empty($inajax) && $msgforward[‘quick‘] && $msgforward[‘messages‘] && @in_array($message, $msgforward[‘messages‘]))) {
         updatesession();
         dheader("location: ".str_replace(‘&‘, ‘&‘, $url_forward));
     }
     if(!empty($infloat)) {
         if($extra) {
             $messagehandle = $extra;
         }
         $extra = ‘‘;
     }
     if(in_array($extra, array(‘HALTED‘, ‘NOPERM‘))) {
         $discuz_action = 254;
     } else {
         $discuz_action = 255;
     }

     include language(‘messages‘);

     $vars = explode(‘:‘, $message);//只要含:就可以了
     if(count($vars) == 2 && isset($scriptlang[$vars[0]][$vars[1]])) {//两个数字即可，用:分割
         eval("\$show_message = \"".str_replace(‘"‘, ‘\"‘, $scriptlang[$vars[0]][$vars[1]])."\";");//$scriptlang未初始化，可以自定义，from www.oldjun.com
     } elseif(isset($language[$message])) {
         $pre = $inajax ? ‘ajax_‘ : ‘‘;
         eval("\$show_message = \"".(isset($language[$pre.$message]) ? $language[$pre.$message] : $language[$message])."\";");
         unset($pre);
     }

     ......
} 
二、DZ的全局机制导致了未初始化的参数可以任意提交：

foreach(array(‘_COOKIE‘, ‘_POST‘, ‘_GET‘) as $_request) {
     foreach($$_request as $_key => $_value) {
         $_key{0} != ‘_‘ && $$_key = daddslashes($_value);
     }
} 
三、misc.php正好有个可以自定义message的点，其实也是未初始化：

elseif($action == ‘imme_binding‘ && $discuz_uid) {

     if(isemail($id)) {
         $msn = $db->result_first("SELECT msn FROM {$tablepre}memberfields WHERE uid=‘$discuz_uid‘");
         $msn = explode("\t", $msn);
         $id = dhtmlspecialchars(substr($id, 0, strpos($id, ‘@‘)));
         $msn = "$msn[0]\t$id";
         $db->query("UPDATE {$tablepre}memberfields SET msn=‘$msn‘ WHERE uid=‘$discuz_uid‘");
         showmessage(‘msn_binding_succeed‘, ‘memcp.php‘);
     } else {
         if($result == ‘Declined‘) {
             dheader("Location: memcp.php");
         } else {
             showmessage($response[‘result‘]);//$response没有初始化，可以自定义，from www.oldjun.com

         }
     }

    }