metasploit-gs/lib/msf/core/exploit/remote/ldap.rb

# -*- coding: binary -*-

#
# This mixin is a wrapper around Net::LDAP
#

require 'rex/proto/ldap'

module Msf
  module Exploit::Remote::LDAP
    # Initialize the LDAP client and set up the LDAP specific datastore
    # options to allow the client to perform authentication and timeout
    # operations. Acts as a wrapper around the caller's
    # implementation of the `initialize` method, which will usually be
    # the module's class's implementation, such as lib/msf/core/auxiliary.rb.
    #
    # @param info [Hash] A hash containing information about the module
    #   using this library which includes its name, description, author, references,
    #   disclosure date, license, actions, default action, default options,
    #   and notes.
    def initialize(info = {})
      super

      register_options([
        Opt::RHOST,
        Opt::RPORT(389),
        OptBool.new('SSL', [false, 'Enable SSL on the LDAP connection', false]),
        OptString.new('BIND_DN', [false, 'The username to authenticate to LDAP server'], fallbacks: ['USERNAME']),
        OptString.new('BIND_PW', [false, 'Password for the BIND_DN'], fallbacks: ['PASSWORD'])
      ])

      register_advanced_options([
        OptFloat.new('LDAP::ConnectTimeout', [true, 'Timeout for LDAP connect', 10.0])
      ])
    end

    # Alias to return the RHOST datastore option.
    #
    # @return [String] The current value of RHOST in the datastore.
    def rhost
      datastore['RHOST']
    end

    # Alias to return the RPORT datastore option.
    #
    # @return [String] The current value of RPORT in the datastore.
    def rport
      datastore['RPORT']
    end

    # Return the peer as a host:port formatted string.
    #
    # @return [String] A string containing the peer details in RHOST:RPORT format.
    def peer
      "#{rhost}:#{rport}"
    end

    # Set the various connection options to use when connecting to the
    # target LDAP server based on the current datastore options. Returns
    # the resulting connection configuration as a hash.
    #
    # @return [Hash] The options to use when connecting to the target
    #    LDAP server.
    def get_connect_opts
      connect_opts = {
        host: rhost,
        port: rport,
        connect_timeout: datastore['LDAP::ConnectTimeout']
      }

      if datastore['SSL']
        connect_opts[:encryption] = {
          method: :simple_tls,
          tls_options: {
            verify_mode: OpenSSL::SSL::VERIFY_NONE
          }
        }
      end

      if datastore['BIND_DN']
        connect_opts[:auth] = {
          method: :simple,
          username: datastore['BIND_DN']
        }
        if datastore['BIND_PW']
          connect_opts[:auth][:password] = datastore['BIND_PW']
        end
      end
      connect_opts
    end

    # Connect to the target LDAP server using the options provided,
    # and pass the resulting connection object to the proc provided.
    # Terminate the connection once the proc finishes executing.
    #
    # @param opts [Hash] Options for the LDAP connection.
    # @param block [Proc] A proc containing the functionality to execute
    #   after the LDAP connection has succeeded. The connection is closed
    #   once this proc finishes executing.
    # @see Net::LDAP.open
    # @return [Object] The result of whatever the block that was
    #   passed in via the "block" parameter yielded.
    def ldap_connect(opts = {}, &block)
      Net::LDAP.open(get_connect_opts.merge(opts), &block)
    end

    # Create a new LDAP connection using Net::LDAP.new and yield the
    # resulting connection object to the caller of this method.
    #
    # @param opts [Hash] A hash containing the connection options for the
    #   LDAP connection to the target server.
    # @yieldparam ldap [Net::LDAP] The LDAP connection handle to use for connecting to
    #   the target LDAP server.
    def ldap_new(opts = {})
      ldap = Net::LDAP.new(get_connect_opts.merge(opts))

      # NASTY, but required
      # monkey patch ldap object in order to ignore bind errors
      # Some servers (e.g. OpenLDAP) return result even after a bind
      # has failed, e.g. with LDAP_INAPPROPRIATE_AUTH - anonymous bind disallowed.
      # See: https://www.openldap.org/doc/admin23/security.html#Authentication%20Methods
      # "Note that disabling the anonymous bind mechanism does not prevent anonymous
      # access to the directory."
      # Bug created for Net:LDAP at https://github.com/ruby-ldap/ruby-net-ldap/issues/375
      #
      # @yieldparam conn [Net::LDAP] The LDAP connection handle to use for connecting to
      #   the target LDAP server.
      # @param args [Hash] A hash containing options for the ldap connection
      def ldap.use_connection(args)
        if @open_connection
          yield @open_connection
        else
          begin
            conn = new_connection
            conn.bind(args[:auth] || @auth)
            # Commented out vs. original
            # result = conn.bind(args[:auth] || @auth)
            # return result unless result.result_code == Net::LDAP::ResultCodeSuccess
            yield conn
          ensure
            conn.close if conn
          end
        end
      end
      yield ldap
    end

    # Get the naming contexts for the target LDAP server.
    #
    # @param ldap [Net::LDAP] The Net::LDAP connection handle for the
    #   current LDAP connection.
    # @return [Net::BER::BerIdentifiedArray] Array of naming contexts for the target LDAP server.
    def get_naming_contexts(ldap)
      vprint_status("#{peer} Getting root DSE")

      unless (root_dse = ldap.search_root_dse)
        print_error("#{peer} Could not retrieve root DSE")
        return
      end

      vprint_line(root_dse.to_ldif)

      naming_contexts = root_dse[:namingcontexts]

      # NOTE: Net::LDAP converts attribute names to lowercase
      if naming_contexts.empty?
        print_error("#{peer} Empty namingContexts attribute")
        return
      end

      naming_contexts
    end

    # Discover the base DN of the target LDAP server via the LDAP
    # server's naming contexts.
    #
    # @param ldap [Net::LDAP] The Net::LDAP connection handle for the
    #   current LDAP connection.
    # @return [String] A string containing the base DN of the target LDAP server.
    def discover_base_dn(ldap)
      # @type [Net::BER::BerIdentifiedArray]
      naming_contexts = get_naming_contexts(ldap)

      unless naming_contexts
        print_error("#{peer} Base DN cannot be determined")
        return
      end

      # NOTE: We assume the first namingContexts value is the base DN
      base_dn = naming_contexts.first

      print_good("#{peer} Discovered base DN: #{base_dn}")
      base_dn
    end

    # Check whether it was possible to successfully bind to the target LDAP
    # server. Raise a RuntimeException with an appropriate error message
    # if not.
    #
    # @param ldap [Net::LDAP] The Net::LDAP connection handle for the
    #   current LDAP connection.
    #
    # @raise [RuntimeError] A RuntimeError will be raised if the LDAP
    #   bind request failed.
    # @return [Nil] This function does not return any data.
    def validate_bind_success!(ldap)
      bind_result = ldap.as_json['result']['ldap_result']

      # Codes taken from https://ldap.com/ldap-result-code-reference-core-ldapv3-result-codes
      case bind_result['resultCode']
      when 0
        vprint_good('Successfully bound to the LDAP server!')
      when 1
        fail_with(Msf::Module::Failure::NoAccess, "An operational error occurred, perhaps due to lack of authorization. The error was: #{bind_result['errorMessage'].strip}")
      when 7
        fail_with(Msf::Module::Failure::NoTarget, 'Target does not support the simple authentication mechanism!')
      when 8
        fail_with(Msf::Module::Failure::NoTarget, "Server requires a stronger form of authentication than we can provide! The error was: #{bind_result['errorMessage'].strip}")
      when 14
        fail_with(Msf::Module::Failure::NoTarget, "Server requires additional information to complete the bind. Error was: #{bind_result['errorMessage'].strip}")
      when 48
        fail_with(Msf::Module::Failure::NoAccess, "Target doesn't support the requested authentication type we sent. Try binding to the same user without a password, or providing credentials if you were doing anonymous authentication.")
      when 49
        fail_with(Msf::Module::Failure::NoAccess, 'Invalid credentials provided!')
      else
        fail_with(Msf::Module::Failure::Unknown, "Unknown error occurred whilst binding: #{bind_result['errorMessage'].strip}")
      end
    end

    # Validate the query result and check whether the query succeeded.
    # Fail with an appropriate error code if the query failed.
    #
    # @param query_result [Hash] A hash containing the results of the query
    #   as a 'resultCode' with an integer representing the result code,
    #   'errorMessage' containing an optional error message, and
    #   'matchedDN' containing the matched DN.
    # @param filter [Net::LDAP::Filter]  A Net::LDAP::Filter to use to
    #   filter the results of the query.
    #
    # @raise [RuntimeError, ArgumentError] A RuntimeError will be raised if the LDAP
    #   request failed. Alternatively, if the query_result parameter isn't a hash, then an
    #   ArgumentError will be raised.
    # @return [Nil] This function does not return any data.
    def validate_query_result!(query_result, filter)
      if query_result.class != Hash
        raise ArgumentError.new('Parameter to "validate_query_result!" function was not a Hash!')
      end

      # Codes taken from https://ldap.com/ldap-result-code-reference-core-ldapv3-result-codes
      case query_result['resultCode']
      when 0
        vprint_status("Successfully queried #{filter}.")
      when 1
        # This is unknown as whilst we could fail on lack of authorization, this is not guaranteed with this error code.
        # The user will need to inspect the error message to determine the root cause of the issue.
        fail_with(Msf::Module::Failure::Unknown, "An LDAP operational error occurred on #{filter}. It is likely the client requires authorization! The error was: #{query_result['errorMessage'].strip}")
      when 2
        fail_with(Msf::Module::Failure::BadConfig, "The LDAP protocol being used by Metasploit isn't supported. The error was #{query_result['errorMessage'].strip}")
      when 3
        fail_with(Msf::Module::Failure::TimeoutExpired, "The LDAP server returned a timeout response to the query #{filter}.")
      when 4
        fail_with(Msf::Module::Failure::UnexpectedReply, "The LDAP query #{filter} was determined to result in too many entries for the LDAP server to return.")
      when 11
        fail_with(Msf::Module::Failure::UnexpectedReply, "The LDAP server indicated that #{filter} hit some administrative limit within the server whilst the request was being processed.")
      when 16
        fail_with(Msf::Module::Failure::NotFound, "The LDAP operation failed for #{filter} because the referenced attribute does not exist.")
      when 18
        fail_with(Msf::Module::Failure::BadConfig, "The LDAP search with #{filter} failed because some matching is not supported for the target attribute type!")
      when 32
        fail_with(Msf::Module::Failure::UnexpectedReply, "The LDAP search with #{filter} failed cause the operation targeted an entity within the base DN that does not exist.")
      when 33
        fail_with(Msf::Module::Failure::BadConfig, "An attempt was made to deference an alias that didn't resolve properly with #{filter}.")
      when 34
        fail_with(Msf::Module::Failure::BadConfig, 'The request included an invalid base DN entry.')
      when 50
        fail_with(Msf::Module::Failure::NoAccess, 'The LDAP operation failed due to insufficient access rights.')
      when 51
        fail_with(Msf::Module::Failure::UnexpectedReply, 'The LDAP operation failed because the server is too busy to perform the request.')
      when 52
        fail_with(Msf::Module::Failure::UnexpectedReply, 'The LDAP operation failed because the server is not currently available to process the request.')
      when 53
        fail_with(Msf::Module::Failure::UnexpectedReply, 'The LDAP operation failed because the server is unwilling to perform the request.')
      when 64
        fail_with(Msf::Module::Failure::Unknown, "The LDAP operation failed due to a naming violation when using #{filter}.")
      when 65
        fail_with(Msf::Module::Failure::Unknown, "The LDAP operation failed due to an object class violation when using #{filter}.")
      else
        if query_result['errorMessage'].blank?
          fail_with(Msf::Module::Failure::Unknown, "Query #{filter} failed but no error message was returned!")
        else
          fail_with(Msf::Module::Failure::Unknown, "Query #{filter} failed with error: #{query_result['errorMessage'].strip}")
        end
      end
    end
  end
end