New alert for https://github.com/mozilla-it/duo_openvpn

Alerts when fDuoSecurity contact fails, which is means either authentication was refused, either granted based on a
single authentication factor ("fail open").

alerts/duo_fail_open.py

@@ -0,0 +1,49 @@
+#!/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
+#
+# Contributors:
+# kang@mozilla.com
+#
+# This script alerts when openvpn's duo security failed to contact the duo server and let the user in.
+# This is a very serious warning that must be acted upon as it means MFA failed and only one factor was validated (in
+# this case a VPN certificate)
+
+from lib.alerttask import AlertTask
+import pyes
+
+class AlertDuoFailOpen(AlertTask):
+    def main(self):
+        # look for events in last 15 mins
+        date_timedelta = dict(minutes=15)
+        # Configure filters using pyes
+        must = [
+            pyes.TermFilter('_type', 'event'),
+            pyes.TermFilter('_source.tags', 'openvpn,duosecurity'),
+            pyes.QueryFilter(pyes.MatchQuery('summary','DuoAPI contact failed','phrase')),
+            pyes.QueryFilter(pyes.MatchQuery('summary','DuoAPI contact failed','phrase')),
+        ]
+        self.filtersManual(date_timedelta, must=must)
+
+        # Search aggregations on field 'sourceipaddress', keep 50 samples of events at most
+        self.searchEventsAggreg('hostname', samplesLimit=1)
+        # alert when >= X matching events in an aggregation
+        # in this case, always
+        self.walkAggregations(threshold=1)
+
+    # Set alert properties
+    def onAggreg(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 = 'bypass'
+        tags = ['openvpn', 'duosecurity']
+        severity = 'WARNING'
+
+        summary = ('DuoSecurity OpenVPN contact failed, fail open triggered on {0}'.aggreg['value']))
+
+        # Create the alert object based on these properties
+        return self.createAlertDict(summary, category, tags, aggreg['events'], severity)