diff --git a/x-pack/plugins/security_solution/server/lib/detection_engine/signals/utils.test.ts b/x-pack/plugins/security_solution/server/lib/detection_engine/signals/utils.test.ts
index 14e12b2ea463..747b0bed3a04 100644
--- a/x-pack/plugins/security_solution/server/lib/detection_engine/signals/utils.test.ts
+++ b/x-pack/plugins/security_solution/server/lib/detection_engine/signals/utils.test.ts
@@ -15,6 +15,9 @@ import { getListArrayMock } from '../../../../common/detection_engine/schemas/ty
 import { getExceptionListItemSchemaMock } from '../../../../../lists/common/schemas/response/exception_list_item_schema.mock';
 import { parseScheduleDates } from '../../../../common/detection_engine/parse_schedule_dates';
 
+// @ts-expect-error
+moment.suppressDeprecationWarnings = true;
+
 import {
   generateId,
   parseInterval,
@@ -32,6 +35,7 @@ import {
   createSearchAfterReturnType,
   mergeReturns,
   createTotalHitsFromSearchResult,
+  lastValidDate,
 } from './utils';
 import { BulkResponseErrorAggregation, SearchAfterAndBulkCreateReturnType } from './types';
 import {
@@ -45,6 +49,7 @@ import {
   sampleEmptyDocSearchResults,
   sampleDocSearchResultsNoSortIdNoHits,
   repeatedSearchResultsWithSortId,
+  sampleDocSearchResultsNoSortId,
 } from './__mocks__/es_results';
 import { ShardError } from '../../types';
 
@@ -967,6 +972,57 @@ describe('utils', () => {
       const { success } = createSearchAfterReturnTypeFromResponse({ searchResult });
       expect(success).toEqual(true);
     });
+
+    test('It will not set an invalid date time stamp from a non-existent @timestamp when the index is not 100% ECS compliant', () => {
+      const searchResult = sampleDocSearchResultsNoSortId();
+      (searchResult.hits.hits[0]._source['@timestamp'] as unknown) = undefined;
+      const { lastLookBackDate } = createSearchAfterReturnTypeFromResponse({ searchResult });
+      expect(lastLookBackDate).toEqual(null);
+    });
+
+    test('It will not set an invalid date time stamp from a null @timestamp when the index is not 100% ECS compliant', () => {
+      const searchResult = sampleDocSearchResultsNoSortId();
+      (searchResult.hits.hits[0]._source['@timestamp'] as unknown) = null;
+      const { lastLookBackDate } = createSearchAfterReturnTypeFromResponse({ searchResult });
+      expect(lastLookBackDate).toEqual(null);
+    });
+
+    test('It will not set an invalid date time stamp from an invalid @timestamp string', () => {
+      const searchResult = sampleDocSearchResultsNoSortId();
+      (searchResult.hits.hits[0]._source['@timestamp'] as unknown) = 'invalid';
+      const { lastLookBackDate } = createSearchAfterReturnTypeFromResponse({ searchResult });
+      expect(lastLookBackDate).toEqual(null);
+    });
+  });
+
+  describe('lastValidDate', () => {
+    test('It returns undefined if the search result contains a null timestamp', () => {
+      const searchResult = sampleDocSearchResultsNoSortId();
+      (searchResult.hits.hits[0]._source['@timestamp'] as unknown) = null;
+      const date = lastValidDate(searchResult);
+      expect(date).toEqual(undefined);
+    });
+
+    test('It returns undefined if the search result contains a undefined timestamp', () => {
+      const searchResult = sampleDocSearchResultsNoSortId();
+      (searchResult.hits.hits[0]._source['@timestamp'] as unknown) = undefined;
+      const date = lastValidDate(searchResult);
+      expect(date).toEqual(undefined);
+    });
+
+    test('It returns undefined if the search result contains an invalid string value', () => {
+      const searchResult = sampleDocSearchResultsNoSortId();
+      (searchResult.hits.hits[0]._source['@timestamp'] as unknown) = 'invalid value';
+      const date = lastValidDate(searchResult);
+      expect(date).toEqual(undefined);
+    });
+
+    test('It returns correct date time stamp if the search result contains an invalid string value', () => {
+      const searchResult = sampleDocSearchResultsNoSortId();
+      (searchResult.hits.hits[0]._source['@timestamp'] as unknown) = 'invalid value';
+      const date = lastValidDate(searchResult);
+      expect(date).toEqual(undefined);
+    });
   });
 
   describe('createSearchAfterReturnType', () => {
diff --git a/x-pack/plugins/security_solution/server/lib/detection_engine/signals/utils.ts b/x-pack/plugins/security_solution/server/lib/detection_engine/signals/utils.ts
index 53089b7f1ca2..93e9622dcb6a 100644
--- a/x-pack/plugins/security_solution/server/lib/detection_engine/signals/utils.ts
+++ b/x-pack/plugins/security_solution/server/lib/detection_engine/signals/utils.ts
@@ -514,6 +514,25 @@ export const createErrorsFromShard = ({ errors }: { errors: ShardError[] }): str
   });
 };
 
+/**
+ * Given a SignalSearchResponse this will return a valid last date if it can find one, otherwise it
+ * will return undefined.
+ * @param result The result to try and parse out the timestamp.
+ */
+export const lastValidDate = (result: SignalSearchResponse): Date | undefined => {
+  if (result.hits.hits.length === 0) {
+    return undefined;
+  } else {
+    const lastTimestamp = result.hits.hits[result.hits.hits.length - 1]._source['@timestamp'];
+    const isValid = lastTimestamp != null && moment(lastTimestamp).isValid();
+    if (!isValid) {
+      return undefined;
+    } else {
+      return new Date(lastTimestamp);
+    }
+  }
+};
+
 export const createSearchAfterReturnTypeFromResponse = ({
   searchResult,
 }: {
@@ -521,10 +540,7 @@ export const createSearchAfterReturnTypeFromResponse = ({
 }): SearchAfterAndBulkCreateReturnType => {
   return createSearchAfterReturnType({
     success: searchResult._shards.failed === 0,
-    lastLookBackDate:
-      searchResult.hits.hits.length > 0
-        ? new Date(searchResult.hits.hits[searchResult.hits.hits.length - 1]?._source['@timestamp'])
-        : undefined,
+    lastLookBackDate: lastValidDate(searchResult),
   });
 };