MozDef/alerts/proxy_exfil_domains.py

53 строки
2.0 KiB
Python

#!/usr/bin/env python
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
# Copyright (c) 2014 Mozilla Corporation
from lib.alerttask import AlertTask
from mozdef_util.query_models import SearchQuery, TermMatch
class AlertProxyExfilDomains(AlertTask):
def main(self):
self.parse_config("proxy_exfil_domains.conf", ["exfil_domains"])
search_query = SearchQuery(minutes=20)
search_query.add_must([TermMatch("category", "proxy")])
for domain in self.config.exfil_domains.split(","):
search_query.add_should([TermMatch("details.host", domain)])
self.filtersManual(search_query)
# Search aggregations on field 'hostname', keep X samples of
# events at most
self.searchEventsAggregated("details.sourceipaddress", samplesLimit=10)
# alert when >= X matching events in an aggregation
# I think it makes sense to alert every time here
self.walkAggregations(threshold=1)
# Set alert properties
def onAggregation(self, aggreg):
# aggreg['count']: number of items in the aggregation, ex: number of failed login attempts
# aggreg['value']: value of the aggregation field, ex: toto@example.com
# aggreg['events']: list of events in the aggregation
category = "squid"
tags = ["squid", "proxy"]
severity = "WARNING"
exfil_domains = set()
for event in aggreg["allevents"]:
domain = event["_source"]["details"]["host"]
exfil_domains.add(domain)
summary = "Suspicious Proxy event(s) detected from {0} to the following exfil domain(s): {1}".format(
aggreg["value"], ",".join(sorted(exfil_domains))
)
# Create the alert object based on these properties
return self.createAlertDict(summary, category, tags, aggreg["events"], severity)