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
    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

    def rhost
      datastore['RHOST']
    end

    def rport
      datastore['RPORT']
    end

    def peer
      "#{rhost}:#{rport}"
    end

    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

    def ldap_connect(opts = {}, &block)
      Net::LDAP.open(get_connect_opts.merge(opts), &block)
    end

    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 https://github.com/ruby-ldap/ruby-net-ldap/issues/375
      #
      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

    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

    def discover_base_dn(ldap)
      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

    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::Exploit::Remote::Failure::NoAccess, "An operational error occurred, perhaps due to lack of authorization. The error was: #{bind_result['errorMessage'].strip}")
      when 7
        fail_with(Msf::Exploit::Remote::Failure::NoTarget, 'Target does not support the simple authentication mechanism!')
      when 8
        fail_with(Msf::Exploit::Remote::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::Exploit::Remote::Failure::NoTarget, "Server requires additional information to complete the bind. Error was: #{bind_result['errorMessage'].strip}")
      when 48
        fail_with(Msf::Exploit::Remote::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::Exploit::Remote::Failure::NoAccess, 'Invalid credentials provided!')
      else
        fail_with(Msf::Exploit::Remote::Failure::Unknown, "Unknown error occurred whilst binding: #{bind_result['errorMessage'].strip}")
      end
    end

    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(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(Failure::BadConfig, "The LDAP protocol being used by Metasploit isn't supported. The error was #{query_result['errorMessage'].strip}")
      when 3
        fail_with(Failure::TimeoutExpired, "The LDAP server returned a timeout response to the query #{filter}.")
      when 4
        fail_with(Failure::UnexpectedReply, "The LDAP query #{filter} was determined to result in too many entries for the LDAP server to return.")
      when 11
        fail_with(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(Failure::NotFound, "The LDAP operation failed for #{filter} because the referenced attribute does not exist.")
      when 18
        fail_with(Failure::BadConfig, "The LDAP search with #{filter} failed because some matching is not supported for the target attribute type!")
      when 32
        fail_with(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(Failure::BadConfig, "An attempt was made to deference an alias that didn't resolve properly with #{filter}.")
      when 34
        fail_with(Failure::BadConfig, 'The request included an invalid base DN entry.')
      when 50
        fail_with(Failure::NoAccess, 'The LDAP operation failed due to insufficient access rights.')
      when 51
        fail_with(Failure::UnexpectedReply, 'The LDAP operation failed because the server is too busy to perform the request.')
      when 52
        fail_with(Failure::UnexpectedReply, 'The LDAP operation failed because the server is not currently available to process the request.')
      when 53
        fail_with(Failure::UnexpectedReply, 'The LDAP operation failed because the server is unwilling to perform the request.')
      when 64
        fail_with(Failure::Unknown, "The LDAP operation failed due to a naming violation when using #{filter}.")
      when 65
        fail_with(Failure::Unknown, "The LDAP operation failed due to an object class violation when using #{filter}.")
      else
        if query_result['errorMessage'].blank?
          fail_with(Failure::Unknown, "Query #{filter} failed but no error message was returned!")
        else
          fail_with(Failure::Unknown, "Query #{filter} failed with error: #{query_result['errorMessage'].strip}")
        end
      end
    end
  end
end