[Response Ops][Alerting] isSnoozeActive can cause Kibana to hang for invalid rRule parameters

[ymao1]

We're seeing an issue where snooze schedules with bymonth or bymonthday set to 0 or [0] are causing an infinite loop inside the isSnoozeActive function.

This is recreateable in the jest tests

diff --git a/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts b/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
index 9fdce331a7d..15b40bb9ea3 100644
--- a/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
+++ b/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
@@ -139,7 +139,7 @@ describe('isSnoozeActive', () => {
         freq: Frequency.YEARLY,
         interval: 1,
         bymonthday: [1],
-        bymonth: [1],
+        bymonth: [[0]],
         tzid: 'Europe/Madrid',
         dtstart: '2023-01-01T00:00:00.000Z',
       } as RRuleRecord,

diff --git a/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts b/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
index 9fdce331a7d..4fb5c91d21d 100644
--- a/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
+++ b/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
@@ -139,7 +139,7 @@ describe('isSnoozeActive', () => {
         freq: Frequency.YEARLY,
         interval: 1,
         bymonthday: [1],
-        bymonth: [1],
+        bymonth: [0],
         tzid: 'Europe/Madrid',
         dtstart: '2023-01-01T00:00:00.000Z',
       } as RRuleRecord,

diff --git a/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts b/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
index 9fdce331a7d..5b78890b780 100644
--- a/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
+++ b/x-pack/plugins/alerting/server/lib/snooze/is_snooze_active.test.ts
@@ -106,7 +106,7 @@ describe('isSnoozeActive', () => {
     const snoozeA = {
       duration: 198000000,
       rRule: {
-        byweekday: ['SA'],
+        byweekday: [0],
         tzid: 'Europe/Madrid',
         freq: Frequency.DAILY,
         interval: 1,

Making these modifications will cause the jest tests to hang.

We need to determine whether this 0 value is a valid configuration for rRule. If it's not, we need to determine how it's being set and prevent this function from going into an infinite loop

[elasticmachine]

Pinging @elastic/response-ops (Team:ResponseOps)

[Zacqary]

0 is not a valid bymonth value. January is 1.

The iCalendar spec implies in one of the examples that invalid dates are supposed to be ignored. So to fix this issue we need to:

• Make therrule library ignore BYMONTH=0 instead of infinitely looping
• Test for invalid values on all properties, for additional safety
• Make sure APIs and UIs can only send valid rrule parameters