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[microsoft-sentinel/microsoft-defender] Improve matching to identify Prevented and add match on parent process name (#1757) #48

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merged 5 commits into from
Nov 7, 2024
Merged

[microsoft-sentinel/microsoft-defender] Improve matching to identify Prevented and add match on parent process name (#1757) #48

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a805066
[microsoft-sentinel] detect alert is prevented
isselparra Nov 5, 2024
8607786
[microsoft-sentinel] verify keywords on alertname
isselparra Nov 5, 2024
879b1d8
[microsoft-defender] Matching on parent process name
RomuDeuxfois Nov 6, 2024
74926d2
[microsoft-sentinel] Matching on parent process name
RomuDeuxfois Nov 6, 2024
ef62319
Format
RomuDeuxfois Nov 6, 2024
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25 changes: 23 additions & 2 deletions microsoft-defender/src/openbas_microsoft_defender.py
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@ def __init__(self):
# TODO Command line
# self.relevant_signatures_types = ["process_name", "command_line", "file_name", "hostname", "ipv4_address"]
self.relevant_signatures_types = [
"parent_process_name",
"process_name",
"file_name",
"hostname",
Expand All @@ -102,6 +103,18 @@ def _extract_process_names(self, alert):
process_names.append(evidence.file_details.file_name)
return process_names

def _extract_parent_process_name(self, alert):
parent_process_names = []
for evidence in alert.evidence:
if (
hasattr(evidence, "parent_process_image_file")
and evidence.parent_process_image_file
):
parent_process_names.append(
evidence.parent_process_image_file.file_name
)
return parent_process_names

def _extract_command_lines(self, alert):
command_lines = []
for evidence in alert.evidence:
Expand Down Expand Up @@ -134,7 +147,7 @@ def _extract_ip_addresses(self, alert):
def _is_prevented(self, alert):
for evidence in alert.evidence:
if evidence.odata_type == "#microsoft.graph.security.processEvidence":
if evidence.detection_status in [
if evidence.detection_status.lower() in [
"prevented",
"remediated",
"blocked",
Expand Down Expand Up @@ -174,6 +187,12 @@ def _match_alert(self, endpoint, alert, expectation):
"data": self._extract_process_names(alert),
"score": 80,
}
elif type == "parent_process_name":
alert_data[type] = {
"type": "fuzzy",
"data": self._extract_parent_process_name(alert),
"score": 80,
}
elif type == "command_line":
alert_data[type] = {
"type": "fuzzy",
Expand Down Expand Up @@ -269,7 +288,9 @@ async def _process_alerts(self, graph_client):
)
for i in range(len(alerts.value)):
alert = alerts.value[i]
alert_date = parse(str(alert.created_date_time)).astimezone(pytz.UTC)
alert_date = parse(str(alert.last_update_date_time)).astimezone(
pytz.UTC
)
if alert_date > limit_date:
result = self._match_alert(endpoint, alert, expectation)
if result is not False:
Expand Down
38 changes: 28 additions & 10 deletions microsoft-sentinel/src/openbas_microsoft_sentinel.py
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Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,7 @@ def __init__(self):

# Initialize signatures helper
self.relevant_signatures_types = [
"parent_process_name",
"process_name",
"command_line",
"file_name",
Expand Down Expand Up @@ -122,6 +123,21 @@ def _extract_process_names(self, columns_index, alert):
process_names.append(entity["Name"])
return process_names

def _extract_parent_process_name(self, columns_index, alert):
parent_process_names = []
entities = json.loads(alert[columns_index["Entities"]])
for entity in entities:
if "Type" in entity and entity["Type"] == "process":
if "ParentProcess" in entity and "ImageFile" in entity["ParentProcess"]:
if (
"ImageFile" in entity["ParentProcess"]
and "Name" in entity["ParentProcess"]["ImageFile"]
):
parent_process_names.append(
entity["ParentProcess"]["ImageFile"]["Name"]
)
return parent_process_names

def _extract_command_lines(self, columns_index, alert):
command_lines = []
entities = json.loads(alert[columns_index["Entities"]])
Expand Down Expand Up @@ -161,17 +177,14 @@ def _extract_ip_addresses(self, columns_index, alert):
return ip_addresses

def _is_prevented(self, columns_index, alert):
extended_properties = json.loads(alert[columns_index["ExtendedProperties"]])
if "Action" in extended_properties and extended_properties["Action"] in [
"blocked",
"quarantine",
"remove",
]:
return True
return False
prevented_keywords = ["blocked", "quarantine", "remove", "prevented"]
alert_name = alert[columns_index["AlertName"]].strip().lower()
result_alert_name = any(
prevented_keyword in alert_name for prevented_keyword in prevented_keywords
)
return result_alert_name

def _match_alert(self, endpoint, columns_index, alert, expectation):
print(alert)
self.helper.collector_logger.info(
"Trying to match alert "
+ str(alert[columns_index["SystemAlertId"]])
Expand Down Expand Up @@ -201,6 +214,12 @@ def _match_alert(self, endpoint, columns_index, alert, expectation):
"data": self._extract_process_names(columns_index, alert),
"score": 80,
}
if type == "parent_process_name":
alert_data[type] = {
"type": "fuzzy",
"data": self._extract_parent_process_name(columns_index, alert),
"score": 80,
}
elif type == "command_line":
alert_data[type] = {
"type": "fuzzy",
Expand Down Expand Up @@ -306,7 +325,6 @@ def _process_alerts(self):
alert_date = parse(
str(alert[columns_index["TimeGenerated"]])
).astimezone(pytz.UTC)
print(alert)
if alert_date > limit_date:
result = self._match_alert(
endpoint, columns_index, alert, expectation
Expand Down