MozDef/alerts/proxy_drop_executable.py

57 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 https://mozilla.org/MPL/2.0/.
# Copyright (c) 2014 Mozilla Corporation
from lib.alerttask import AlertTask
from mozdef_util.query_models import QueryStringMatch, SearchQuery, TermMatch
class AlertProxyDropExecutable(AlertTask):
def main(self):
self.parse_config("proxy_drop_executable.conf", ["extensions"])
search_query = SearchQuery(minutes=20)
search_query.add_must(
[
TermMatch("category", "proxy"),
TermMatch("details.proxyaction", "TCP_DENIED"),
]
)
# Only notify on certain file extensions from config
filename_regex = r"/.*\.({0})/".format(self.config.extensions.replace(",", "|"))
search_query.add_must(
[QueryStringMatch("details.destination: {}".format(filename_regex))]
)
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):
category = "squid"
tags = ["squid", "proxy"]
severity = "WARNING"
dropped_urls = set()
for event in aggreg["allevents"]:
dropped_urls.add(event["_source"]["details"]["destination"])
summary = "Suspicious Proxy DROP event(s) detected from {0} to the following executable file destination(s): {1}".format(
aggreg["value"], ",".join(sorted(dropped_urls))
)
# Create the alert object based on these properties
return self.createAlertDict(summary, category, tags, aggreg["events"], severity)