---
title: Route table changes should be monitored
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: Docs > Datadog Security > OOTB Rules > Route table changes should be monitored
---

> For the complete documentation index, see [llms.txt](https://docs.datadoghq.com/llms.txt).

# Route table changes should be monitored
 
## Description{% #description %}

AWS accounts should have at least one active multi-region CloudTrail trail that captures all management events (an event selector with `IncludeManagementEvents` set to `true` and `ReadWriteType` set to `All`), sends its logs to CloudWatch Logs, and has a metric filter and alarm for route table changes (`CreateRoute`, `CreateRouteTable`, `ReplaceRoute`, `ReplaceRouteTableAssociation`, `DeleteRouteTable`, `DeleteRoute`, `DisassociateRouteTable`). The alarm must notify an SNS topic with at least one confirmed subscriber so that changes to VPC routing are detected in real time. An optional `$.eventSource = ec2.amazonaws.com` clause in the filter pattern is accepted but not required.

## Remediation{% #remediation %}

1. Create a metric filter on the log group of the active multi-region trail and an SNS topic with a subscription, as described in the [CloudWatch alarms for CloudTrail guide](https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudwatch-alarms-for-cloudtrail.html):

```plaintext
aws logs put-metric-filter --log-group-name <trail-log-group-name> \
--filter-name <route-table-changes-metric> --metric-transformations \
metricName=<route-table-changes-metric>,metricNamespace='CISBenchmark',metricValue=1 \
--filter-pattern '{ ($.eventName = CreateRoute) || ($.eventName = CreateRouteTable) || ($.eventName = ReplaceRoute) || ($.eventName = ReplaceRouteTableAssociation) || ($.eventName = DeleteRouteTable) || ($.eventName = DeleteRoute) || ($.eventName = DisassociateRouteTable) }'
aws sns create-topic --name <sns-topic-name>
aws sns subscribe --topic-arn <sns-topic-arn> --protocol <sns-protocol> --notification-endpoint <sns-subscription-endpoints>
```
Create an alarm on the metric that notifies the SNS topic:
```plaintext
aws cloudwatch put-metric-alarm --alarm-name <route-table-changes-alarm> --metric-name <route-table-changes-metric> \
--statistic Sum --period 300 --threshold 1 --comparison-operator GreaterThanOrEqualToThreshold \
--evaluation-periods 1 --namespace 'CISBenchmark' --alarm-actions <sns-topic-arn>
```

## References{% #references %}

- [Creating CloudWatch alarms for CloudTrail events](https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudwatch-alarms-for-cloudtrail.html)
- [Logging management events with CloudTrail](https://docs.aws.amazon.com/awscloudtrail/latest/userguide/logging-management-events-with-cloudtrail.html)
- [Create a metric filter for a log group](https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/CreateMetricFilterProcedure.html)
- [CIS Amazon Web Services Benchmarks](https://www.cisecurity.org/benchmark/amazon_web_services)