[lookup_tables] Support lookup tables

stream_alert/rule_processor/rules_engine.py

@@ -22,23 +22,47 @@
 from stream_alert.shared import NORMALIZATION_KEY, resources
 from stream_alert.shared.alert import Alert
 from stream_alert.shared.rule import import_folders, Rule
+from stream_alert.shared.lookup_tables import LookupTables
 from stream_alert.shared.rule_table import RuleTable
 
-
 _IGNORE_KEYS = {StreamThreatIntel.IOC_KEY, NORMALIZATION_KEY}
 
 
 class RulesEngine(object):
     """Class to act as a rules engine that processes rules"""
     _RULE_TABLE_LAST_REFRESH = datetime(year=1970, month=1, day=1)
+    _LOOKUP_TABLES = {}
     _RULE_TABLE = None
 
     def __init__(self, config, *rule_paths):
         """Initialize a RulesEngine instance to cache a StreamThreatIntel instance."""
+
         self._threat_intel = StreamThreatIntel.load_from_config(config)
         self._required_outputs_set = resources.get_required_outputs()
         import_folders(*rule_paths)
         self._load_rule_table(config)
+        lookup_tables = LookupTables.load_lookup_tables(config)
+        if lookup_tables:
+            RulesEngine._LOOKUP_TABLES = lookup_tables.download_s3_objects()
+
+    @classmethod
+    def get_lookup_table(cls, table_name):
+        """Return lookup table by table name
+
+        Rule Processor supports to load arbitrary json files from S3 buckets into
+        memory for quick reference while writing rules. This information is stored
+        in class variable `_LOOKUP_TABLES` which is a dictionary. Json file name
+        without extension will the key name(a.k.a table_name), and json content
+        will be the value.
+
+        Args:
+            table_name (str): Lookup table name. It is also the json file name without
+                extension.
+
+        Returns:
+            dict: A dictionary contains lookup table information.
+        """
+        return cls._LOOKUP_TABLES.get(table_name)
 
     @classmethod
     def _load_rule_table(cls, config):

stream_alert/shared/lookup_tables.py

@@ -0,0 +1,104 @@
+"""
+Copyright 2017-present, Airbnb Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+from datetime import datetime, timedelta
+import json
+import os
+import time
+
+import boto3
+from botocore.exceptions import ClientError
+
+from stream_alert.shared import LOGGER
+
+class LookupTables(object):
+    """Lookup Tables to useful information which can be referenced from rules"""
+
+    _LOOKUP_TABLES_LAST_REFRESH = datetime(year=1970, month=1, day=1)
+
+    def __init__(self, buckets_info):
+        self._s3_client = boto3.resource('s3')
+        self._buckets_info = buckets_info
+
+    def download_s3_objects(self):
+        """Download S3 files (json format) from S3 buckets into memory.
+
+        Returns:
+            dict: A dictionary contains information loaded from S3. The file name
+                will be the key, and value is file content in json format.
+        """
+
+        _lookup_tables = {}
+
+        for bucket, files in self._buckets_info.iteritems():
+            for json_file in files:
+                table_name = os.path.splitext(json_file)[0]
+                try:
+                    start_time = time.time()
+                    s3_object = self._s3_client.Object(bucket, json_file).get()
+                    size_kb = round(s3_object.get('ContentLength') / 1024.0, 2)
+                    size_mb = round(size_kb / 1024.0, 2)
+                    display_size = '{}MB'.format(size_mb) if size_mb else '{}KB'.format(size_kb)
+                    LOGGER.info('Downloaded S3 file size %s and updated lookup table %s',
+                                display_size, table_name)
+                    _lookup_tables[table_name] = json.loads(s3_object.get('Body').read())
+                except ClientError as err:
+                    LOGGER.error('Encounterred error while downloading %s from %s, %s',
+                                 json_file, bucket, err.response['Error']['Message'])
+                    return _lookup_tables
+
+                total_time = time.time() - start_time
+                LOGGER.info('Downloaded S3 file %s seconds', round(total_time, 2))
+
+        return _lookup_tables
+
+    @classmethod
+    def load_lookup_tables(cls, config):
+        """Load arbitrary json files to memory from S3 buckets when lookup table enabled
+
+        The lookup tables will also be refreshed based on "cache_refresh_minutes" setting
+        in the config.
+
+        Args:
+            config (dict): Loaded configuration from 'conf/' directory
+
+        Returns:
+            Return False if lookup table enabled or missing config. Otherwise, it
+                will return an instance of LookupTables class.
+        """
+        lookup_tables = config['global']['infrastructure'].get('lookup_tables')
+        if not (lookup_tables and lookup_tables.get('enabled', False)):
+            return False
+
+        buckets_info = lookup_tables.get('buckets')
+        if not buckets_info:
+            LOGGER.error('Buckets not defined')
+            return False
+
+        lookup_refresh_interval = lookup_tables.get('cache_refresh_minutes', 10)
+        now = datetime.utcnow()
+        refresh_delta = timedelta(minutes=lookup_refresh_interval)
+        needs_refresh = cls._LOOKUP_TABLES_LAST_REFRESH + refresh_delta < now
+        if not needs_refresh:
+            LOGGER.debug('lookup tables do not need refresh (last refresh time: %s; '
+                         'current time: %s)', cls._LOOKUP_TABLES_LAST_REFRESH, now)
+            return False
+
+        LOGGER.info('Refreshing lookup tables (last refresh time: %s; current time: %s)',
+                    cls._LOOKUP_TABLES_LAST_REFRESH, now)
+
+        cls._LOOKUP_TABLES_LAST_REFRESH = now
+
+        return cls(buckets_info)

stream_alert_cli/helpers.py

@@ -663,6 +663,29 @@ def put_mock_s3_object(bucket, key, data, region):
 
     s3_client.put_object(Body=data, Bucket=bucket, Key=key, ServerSideEncryption='AES256')
 
+def mock_s3_bucket(config):
+    """Mock S3 bucket for lookup tables testing"""
+    region = config['global']['account']['region']
+    lookup_tables_config = config['global']['infrastructure'].get('lookup_tables')
+    if lookup_tables_config:
+        buckets_info = lookup_tables_config.get(
+            'buckets', {'test_buckets': ['foo.json', 'bar.json']}
+        )
+    else:
+        buckets_info = {'test_buckets': ['foo.json', 'bar.json']}
+
+    for bucket, files in buckets_info.iteritems():
+        for json_file in files:
+            test_json_file = os.path.join('tests/integration/fixtures', json_file)
+            if os.path.isfile(test_json_file):
+                data = open(test_json_file, 'r')
+            else:
+                data = json.dumps({'key': 'value'})
+            put_mock_s3_object(bucket, json_file, data, region)
+
+            if isinstance(data, file):
+                data.close()
+
 
 def mock_me(context):
     """Decorator function for wrapping framework in mock calls

stream_alert_cli/test.py

@@ -1041,6 +1041,8 @@ def run_tests(options, context):
         # Run the rule processor for all rules or designated rule set
         if context.mocked:
             helpers.setup_mock_alerts_table(alerts_table)
+            # Mock S3 bucket for lookup tables testing
+            helpers.mock_s3_bucket(config)
 
         rule_proc_tester = RuleProcessorTester(context, config, test_rules)
         alert_proc_tester = AlertProcessorTester(config, context)

tests/unit/conf/global.json

@@ -14,6 +14,16 @@
       "read_capacity": 5,
       "write_capacity": 5
     },
+    "lookup_tables": {
+      "buckets": {
+        "bucket_name": [
+          "foo.json",
+          "bar.json"
+        ]
+      },
+      "cache_refresh_minutes": 10,
+      "enabled": false
+    },
     "monitoring": {
       "create_sns_topic": true
     },

tests/unit/stream_alert_rule_processor/test_rules_engine.py

@@ -13,12 +13,13 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 """
-# pylint: disable=no-self-use,protected-access,attribute-defined-outside-init
+# pylint: disable=no-self-use,protected-access,attribute-defined-outside-init,too-many-lines
 from datetime import datetime, timedelta
 import json
 import os
 
 from mock import Mock, patch
+from moto import mock_s3
 from nose.tools import (
     assert_equal,
     assert_false,
@@ -27,12 +28,14 @@
     assert_true,
 )
 
+from stream_alert_cli.helpers import put_mock_s3_object
 from stream_alert.rule_processor.parsers import get_parser
 from stream_alert.rule_processor.rules_engine import RulesEngine
 from stream_alert.shared import NORMALIZATION_KEY
 from stream_alert.shared.config import load_config
 from stream_alert.shared.rule import disable, matcher, Matcher, rule, Rule
 from stream_alert.shared.rule_table import RuleTable
+from stream_alert.shared.lookup_tables import LookupTables
 
 from tests.unit.stream_alert_rule_processor.test_helpers import (
     load_and_classify_payload,
@@ -54,8 +57,14 @@ def setup(self):
         Rule._rules.clear()
         self.config = load_config('tests/unit/conf')
         self.config['global']['threat_intel']['enabled'] = False
+        self.config['global']['infrastructure']['lookup_tables']['enabled'] = False
         self.rules_engine = RulesEngine(self.config)
 
+    def teardown(self):
+        """Clean up setup for lookup tables"""
+        RulesEngine._LOOKUP_TABLES = {}
+        LookupTables._LOOKUP_TABLES_LAST_REFRESH = datetime(year=1970, month=1, day=1)
+
     def test_basic_rule_matcher_process(self):
         """Rules Engine - Basic Rule/Matcher"""
         @matcher
@@ -945,3 +954,42 @@ def rule_staged_only(_): # pylint: disable=unused-variable
 
             # alert tests
             assert_equal(list(alerts[0].outputs)[0], 'aws-firehose:alerts')
+
+    @patch('logging.Logger.error')
+    def test_load_lookup_tables_missing_config(self, mock_logger):
+        """Rules Engine - Load lookup tables with missing config"""
+        self.config['global']['infrastructure'].pop('lookup_tables')
+        _ = RulesEngine(self.config)
+        assert_equal(RulesEngine._LOOKUP_TABLES, {})
+        assert_equal(LookupTables._LOOKUP_TABLES_LAST_REFRESH,
+                     datetime(year=1970, month=1, day=1))
+        assert_equal(RulesEngine.get_lookup_table('table_name'), None)
+
+        self.config['global']['infrastructure']['lookup_tables'] = {
+            'cache_refresh_minutes': 10,
+            'enabled': True
+        }
+        _ = RulesEngine(self.config)
+        mock_logger.assert_called_with('Buckets not defined')
+
+    @patch('logging.Logger.debug')
+    def test_load_lookup_tables(self, mock_logger):
+        """Rules Engine - Load lookup table"""
+        s3_mock = mock_s3()
+        s3_mock.start()
+        put_mock_s3_object(
+            'bucket_name', 'foo.json', json.dumps({'key1': 'value1'}), 'us-east-1'
+        )
+        put_mock_s3_object(
+            'bucket_name', 'bar.json', json.dumps({'key2': 'value2'}), 'us-east-1'
+        )
+        self.config['global']['infrastructure']['lookup_tables']['enabled'] = True
+        _ = RulesEngine(self.config)
+        assert_equal(RulesEngine.get_lookup_table('foo'), {'key1': 'value1'})
+        assert_equal(RulesEngine.get_lookup_table('bar'), {'key2': 'value2'})
+        assert_equal(RulesEngine.get_lookup_table('not_exist'), None)
+
+        _ = RulesEngine(self.config)
+        mock_logger.assert_called()
+
+        s3_mock.stop()