def _validate_eql(ecs_versions, indexes, query, name):
# validate against all specified schemas or the latest if none specified
parsed = eql.parse_query(query)
beat_types = [index.split("-")[0] for index in indexes if "beat-*" in index]
beat_schema = beats.get_schema_from_eql(parsed, beat_types) if beat_types else None
ecs_versions = ecs_versions or [ecs_versions]
schemas = []
for version in ecs_versions:
try:
schemas.append(ecs.get_kql_schema(indexes=indexes, beat_schema=beat_schema, version=version))
except KeyError:
raise KeyError('Unknown ecs schema version: {} in rule {}.\n'
'Do you need to update schemas?'.format(version, name)) from None
for schema in schemas:
try:
with ecs.KqlSchema2Eql(schema):
eql.parse_query(query)
except eql.EqlTypeMismatchError:
raise
except eql.EqlParseError as exc:
message = exc.error_msg
trailer = None
if "Unknown field" in message and beat_types:
trailer = "\nTry adding event.module and event.dataset to specify beats module"
raise type(exc)(exc.error_msg, exc.line, exc.column, exc.source,
len(exc.caret.lstrip()), trailer=trailer) from None
def assert_normalization_match(self,
standard_query,
converted,
source="Microsoft Sysmon"):
parsed_original = eql.parse_query(standard_query)
parsed_converted = eql.parse_query(converted)
normalizer = self.config.normalizers[source]
converted = normalizer.normalize_ast(parsed_original)
self.assertEqual(str(parsed_converted), str(converted))
def validate(self, data: 'QueryRuleData', meta: RuleMeta) -> None:
"""Validate an EQL query while checking TOMLRule."""
_ = self.ast
if meta.query_schema_validation is False or meta.maturity == "deprecated":
# syntax only, which is done via self.ast
return
indexes = data.index or []
beats_version = meta.beats_version or beats.get_max_version()
ecs_versions = meta.ecs_versions or [ecs.get_max_version()]
# TODO: remove once py-eql supports ipv6 for cidrmatch
# Or, unregister the cidrMatch function and replace it with one that doesn't validate against strict IPv4
with eql.parser.elasticsearch_syntax, eql.parser.ignore_missing_functions:
parsed = eql.parse_query(self.query)
beat_types = [
index.split("-")[0] for index in indexes if "beat-*" in index
]
beat_schema = beats.get_schema_from_eql(
parsed, beat_types, version=beats_version) if beat_types else None
for version in ecs_versions:
schema = ecs.get_kql_schema(indexes=indexes,
beat_schema=beat_schema,
version=version)
eql_schema = ecs.KqlSchema2Eql(schema)
try:
# TODO: switch to custom cidrmatch that allows ipv6
with eql_schema, eql.parser.elasticsearch_syntax, eql.parser.ignore_missing_functions:
eql.parse_query(self.query)
except eql.EqlTypeMismatchError:
raise
except eql.EqlParseError as exc:
message = exc.error_msg
trailer = None
if "Unknown field" in message and beat_types:
trailer = "\nTry adding event.module or event.dataset to specify beats module"
raise exc.__class__(exc.error_msg,
exc.line,
exc.column,
exc.source,
len(exc.caret.lstrip()),
trailer=trailer) from None
def test_invalid_normalization(self):
original = eql.parse_query(
"registry where concat(registry_key) == 'blah'")
with self.assertRaises(eql.EqlCompileError):
normalizer = self.config.normalizers["Endgame Platform"]
normalizer.normalize_ast(original)
def _execute_eql_query(self, events, query):
"""
Execute an EQL query on the provided events.
:param events: events
:param query: EQL query
:return: the result of the query as a list of dictionaries or None when the query did not match the schema
"""
schema = eql.Schema.learn(events)
query_result = []
# this function is used to store the result of the query to 'query_result'
def store_result(result):
for event in result.events:
query_result.append(event.data)
engine = eql.PythonEngine()
with schema:
try:
eql_query = eql.parse_query(query, implied_any=True, implied_base=True)
engine.add_query(eql_query)
except eql.EqlError as e:
print(e, file=sys.stderr)
print('\nTake into account the following schema:')
pprint(schema.schema)
return None
engine.add_output_hook(store_result)
# execute the query
engine.stream_events(events)
return query_result
def _execute_eql_query(events, query):
"""
Execute an EQL query against the provided events
:param events: events
:param query: EQL query
:return: the query results (i.e. filtered events) or None when the query did not match the schema
"""
# learn and load the schema
schema = eql.Schema.learn(events)
query_results = []
def callback(results):
for event in results.events:
query_results.append(event.data)
# create the engine and parse the query
engine = eql.PythonEngine()
with schema:
try:
eql_query = eql.parse_query(query, implied_any=True, implied_base=True)
engine.add_query(eql_query)
except eql.EqlError as e:
print(e, file=sys.stderr)
print('\nTake into account the following schema:')
pprint(schema.schema)
# when using an EQL query that does not match the schema, return None.
return None
engine.add_output_hook(callback)
# execute the query
engine.stream_events(events)
return query_results
def parsed_query(self):
if self.query:
if self.contents['language'] == 'kuery':
return kql.parse(self.query)
elif self.contents['language'] == 'eql':
# TODO: remove once py-eql supports ipv6 for cidrmatch
with eql.parser.elasticsearch_syntax, eql.parser.ignore_missing_functions:
return eql.parse_query(self.query)
def from_eql(tree, optimize=True):
if not isinstance(tree, eql.ast.EqlNode):
try:
tree = eql.parse_query(tree, implied_any=True)
except eql.EqlSemanticError:
tree = eql.parse_expression(tree)
converted = Eql2Kql().walk(tree)
return converted.optimize(recursive=True) if optimize else converted
def get_unique_query_fields(cls, rule_contents):
"""Get a list of unique fields used in a rule query from rule contents."""
query = rule_contents.get('query')
language = rule_contents.get('language')
if language in ('kuery', 'eql'):
# TODO: remove once py-eql supports ipv6 for cidrmatch
with eql.parser.elasticsearch_syntax, eql.parser.ignore_missing_functions:
parsed = kql.parse(query) if language == 'kuery' else eql.parse_query(query)
return sorted(set(str(f) for f in parsed if isinstance(f, (eql.ast.Field, kql.ast.Field))))
def get_unique_query_fields(cls, rule_contents):
"""Get a list of unique fields used in a rule query from rule contents."""
query = rule_contents.get('query')
language = rule_contents.get('language')
if language in ('kuery', 'eql'):
parsed = kql.parse(
query) if language == 'kuery' else eql.parse_query(query)
return sorted(
set(
str(f) for f in parsed
if isinstance(f, (eql.ast.Field, kql.ast.Field))))
def search_rules(query, columns, language, verbose=True):
"""Use KQL or EQL to find matching rules."""
from kql import get_evaluator
from eql.table import Table
from eql.build import get_engine
from eql import parse_query
from eql.pipes import CountPipe
flattened_rules = []
for file_name, rule_doc in rule_loader.load_rule_files().items():
flat = {"file": os.path.relpath(file_name)}
flat.update(rule_doc)
flat.update(rule_doc["metadata"])
flat.update(rule_doc["rule"])
attacks = [
threat for threat in rule_doc["rule"].get("threat", [])
if threat["framework"] == "MITRE ATT&CK"
]
techniques = [
t["id"] for threat in attacks for t in threat.get("technique", [])
]
tactics = [threat["tactic"]["name"] for threat in attacks]
flat.update(techniques=techniques, tactics=tactics)
flattened_rules.append(flat)
flattened_rules.sort(key=lambda dct: dct["name"])
filtered = []
if language == "kql":
evaluator = get_evaluator(query) if query else lambda x: True
filtered = list(filter(evaluator, flattened_rules))
elif language == "eql":
parsed = parse_query(query, implied_any=True, implied_base=True)
evaluator = get_engine(parsed)
filtered = [
result.events[0].data for result in evaluator(flattened_rules)
]
if not columns and any(
isinstance(pipe, CountPipe) for pipe in parsed.pipes):
columns = ["key", "count", "percent"]
if columns:
columns = ",".join(columns).split(",")
else:
columns = ["rule_id", "file", "name"]
table = Table.from_list(columns, filtered)
if verbose:
click.echo(table)
return filtered
def validate(self, data: 'QueryRuleData', meta: RuleMeta) -> None:
"""Validate an EQL query while checking TOMLRule."""
ast = self.ast
if meta.query_schema_validation is False or meta.maturity == "deprecated":
# syntax only, which is done via self.ast
return
for stack_version, mapping in meta.get_validation_stack_versions(
).items():
beats_version = mapping['beats']
ecs_version = mapping['ecs']
err_trailer = f'stack: {stack_version}, beats: {beats_version}, ecs: {ecs_version}'
beat_types = beats.parse_beats_from_index(data.index)
beat_schema = beats.get_schema_from_kql(
ast, beat_types, version=beats_version) if beat_types else None
schema = ecs.get_kql_schema(version=ecs_version,
indexes=data.index or [],
beat_schema=beat_schema)
eql_schema = ecs.KqlSchema2Eql(schema)
try:
# TODO: switch to custom cidrmatch that allows ipv6
with eql_schema, eql.parser.elasticsearch_syntax, eql.parser.ignore_missing_functions:
eql.parse_query(self.query)
except eql.EqlParseError as exc:
message = exc.error_msg
trailer = err_trailer
if "Unknown field" in message and beat_types:
trailer = f"\nTry adding event.module or event.dataset to specify beats module\n\n{trailer}"
raise exc.__class__(exc.error_msg,
exc.line,
exc.column,
exc.source,
len(exc.caret.lstrip()),
trailer=trailer) from None
except Exception:
print(err_trailer)
raise
def validate_query(self, beats_version: str, ecs_versions: List[str]):
"""Validate an EQL query while checking TOMLRule."""
# TODO: remove once py-eql supports ipv6 for cidrmatch
# Or, unregister the cidrMatch function and replace it with one that doesn't validate against strict IPv4
with eql.parser.elasticsearch_syntax, eql.parser.ignore_missing_functions:
parsed = eql.parse_query(self.query)
beat_types = [
index.split("-")[0] for index in self.index or []
if "beat-*" in index
]
beat_schema = beats.get_schema_from_eql(
parsed, beat_types, version=beats_version) if beat_types else None
for version in ecs_versions:
schema = ecs.get_kql_schema(indexes=self.index or [],
beat_schema=beat_schema,
version=version)
try:
# TODO: switch to custom cidrmatch that allows ipv6
with ecs.KqlSchema2Eql(
schema
), eql.parser.elasticsearch_syntax, eql.parser.ignore_missing_functions:
eql.parse_query(self.query)
except eql.EqlTypeMismatchError:
raise
except eql.EqlParseError as exc:
message = exc.error_msg
trailer = None
if "Unknown field" in message and beat_types:
trailer = "\nTry adding event.module or event.dataset to specify beats module"
raise exc.__class__(exc.error_msg,
exc.line,
exc.column,
exc.source,
len(exc.caret.lstrip()),
trailer=trailer) from None
def add_analytic(self, analytic):
if isinstance(analytic, dict) and list(
analytic.keys()) == ['analytic']:
analytic = analytic['analytic']
Analytic.validate(analytic)
analytic['metadata']['_source'] = analytic['query']
analytic = eql.ast.EqlAnalytic(metadata=analytic['metadata'],
query=eql.parse_query(
analytic['query']))
self.analytic_lookup[analytic.id] = analytic
self.analytics.append(analytic)
for tactic in analytic.metadata.get('tactics', []):
for technique in analytic.metadata.get('techniques', []):
self.coverage[tactic][technique].append(analytic)
def add_analytic(self, analytic, path=None): # type: (dict, str) -> None
if isinstance(analytic, dict) and list(
analytic.keys()) == ['analytic']:
analytic = analytic['analytic']
Analytic.validate(analytic)
analytic['metadata']['_source'] = '\n'.join(
l.rstrip() for l in analytic['query'].strip().splitlines())
if path:
analytic['metadata']['_path'] = path
analytic = eql.ast.EqlAnalytic(metadata=analytic['metadata'],
query=eql.parse_query(
analytic['query']))
self.analytic_lookup[analytic.id] = analytic
self.analytics.append(analytic)
for tactic in analytic.metadata.get('tactics', []):
for technique in analytic.metadata.get('techniques', []):
self.coverage[tactic][technique].append(analytic)
def parsed_query(self) -> kql.ast.Expression:
with eql.parser.elasticsearch_syntax, eql.parser.ignore_missing_functions:
return eql.parse_query(self.query)
def parse(text):
try:
return parse_query(text, implied_base=True, implied_any=True)
except EqlError as exc:
print(exc, file=sys.stderr)
sys.exit(2)
def assert_normalization_match(self, standard_query, sysmon_query):
parsed_original = eql.parse_query(standard_query)
parsed_sysmon = eql.parse_query(sysmon_query)
converted = self.sysmon_normalizer.normalize_ast(parsed_original)
self.assertEqual(parsed_sysmon, converted)
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from eql import parse_query, ParseError
import argparse, sys
if __name__ == '__main__':
parser = argparse.ArgumentParser(
description='check an eql query for valid syntax against the eql parser'
)
parser.add_argument('--query',
'-q',
help='the eql query to check for valid syntax')
args = parser.parse_args()
if not args.query:
print("Must specify the --query or -q parameter")
sys.exit(-1)
eql_query = args.query
try:
_ = parse_query(eql_query)
except ParseError as e:
print("eql_error: {0}".format(e.message))
sys.exit(-1)
sys.exit(0)
def search_rules(query,
columns,
language,
count,
verbose=True,
rules: Dict[str, dict] = None,
pager=False):
"""Use KQL or EQL to find matching rules."""
from kql import get_evaluator
from eql.table import Table
from eql.build import get_engine
from eql import parse_query
from eql.pipes import CountPipe
flattened_rules = []
rules = rules or rule_loader.load_rule_files(verbose=verbose)
for file_name, rule_doc in rules.items():
flat = {"file": os.path.relpath(file_name)}
flat.update(rule_doc)
flat.update(rule_doc["metadata"])
flat.update(rule_doc["rule"])
tactic_names = []
technique_ids = []
subtechnique_ids = []
for entry in rule_doc['rule'].get('threat', []):
if entry["framework"] != "MITRE ATT&CK":
continue
techniques = entry.get('technique', [])
tactic_names.append(entry['tactic']['name'])
technique_ids.extend([t['id'] for t in techniques])
subtechnique_ids.extend([
st['id'] for t in techniques
for st in t.get('subtechnique', [])
])
flat.update(techniques=technique_ids,
tactics=tactic_names,
subtechniques=subtechnique_ids,
unique_fields=Rule.get_unique_query_fields(
rule_doc['rule']))
flattened_rules.append(flat)
flattened_rules.sort(key=lambda dct: dct["name"])
filtered = []
if language == "kql":
evaluator = get_evaluator(query) if query else lambda x: True
filtered = list(filter(evaluator, flattened_rules))
elif language == "eql":
parsed = parse_query(query, implied_any=True, implied_base=True)
evaluator = get_engine(parsed)
filtered = [
result.events[0].data for result in evaluator(flattened_rules)
]
if not columns and any(
isinstance(pipe, CountPipe) for pipe in parsed.pipes):
columns = ["key", "count", "percent"]
if count:
click.echo(f'{len(filtered)} rules')
return filtered
if columns:
columns = ",".join(columns).split(",")
else:
columns = ["rule_id", "file", "name"]
table = Table.from_list(columns, filtered)
if verbose:
click.echo_via_pager(table) if pager else click.echo(table)
return filtered
def parsed_query(self):
if self.query:
if self.contents['language'] == 'kuery':
return kql.parse(self.query)
elif self.contents['language'] == 'eql':
return eql.parse_query(self.query)
