Detections
Analytics

4.14 Ensure VPC changes are monitored

Information

Real-time monitoring of API calls can be achieved by directing CloudTrail Logs to CloudWatch Logs or an external Security Information and Event Management (SIEM) environment, and establishing corresponding metric filters and alarms.

It is possible to have more than one VPC within an account; additionally, it is also possible to create a peer connection between two VPCs, enabling network traffic to route between them.

It is recommended that a metric filter and alarm be established for changes made to VPCs.

CloudWatch is an AWS native service that allows you to observe and monitor resources and applications. CloudTrail logs can also be sent to an external Security Information and Event Management (SIEM) environment for monitoring and alerting.

VPCs in AWS are logically isolated virtual networks that can be used to launch AWS resources. Monitoring changes to VPC configurations will help ensure that VPC traffic flow is not negatively impacted. Changes to VPCs can affect network accessibility from the public internet and additionally impact VPC traffic flow to and from the resources launched in the VPC.

NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.

Solution

If you are using CloudTrail trails and CloudWatch, perform the following steps to set up the metric filter, alarm, SNS topic, and subscription:

 -

Create a metric filter based on the provided filter pattern that checks for VPC changes and uses the <trail-log-group-name> taken from audit step 1:

aws logs put-metric-filter --log-group-name <trail-log-group-name> --filter-name <vpc-changes-metric> --metric-transformations metricName=<vpc-changes-metric>,metricNamespace='CISBenchmark',metricValue=1 --filter-pattern '{ ($.eventName = CreateVpc) || ($.eventName = DeleteVpc) || ($.eventName = ModifyVpcAttribute) || ($.eventName = AcceptVpcPeeringConnection) || ($.eventName = CreateVpcPeeringConnection) || ($.eventName = DeleteVpcPeeringConnection) || ($.eventName = RejectVpcPeeringConnection) || ($.eventName = AttachClassicLinkVpc) || ($.eventName = DetachClassicLinkVpc) || ($.eventName = DisableVpcClassicLink) || ($.eventName = EnableVpcClassicLink) }'

Note : You can choose your own metricName and metricNamespace strings. Using the same metricNamespace for all Foundations Benchmark metrics will group them together.

 -

Create an SNS topic that the alarm will notify:

aws sns create-topic --name <sns-topic-name>

Note : You can execute this command once and then reuse the same topic for all monitoring alarms.

Note : Capture the TopicArn that is displayed when creating the SNS topic in step 2.

 -

Create an SNS subscription for the topic created in step 2:

aws sns subscribe --topic-arn <sns-topic-arn> --protocol <sns-protocol> --notification-endpoint <sns-subscription-endpoints>

Note : You can execute this command once and then reuse the same subscription for all monitoring alarms.

 -

Create an alarm that is associated with the CloudWatch Logs metric filter created in step 1 and the SNS topic created in step 2:

aws cloudwatch put-metric-alarm --alarm-name <vpc-changes-alarm> --metric-name <vpc-changes-metric> --statistic Sum --period 300 --threshold 1 --comparison-operator GreaterThanOrEqualToThreshold --evaluation-periods 1 --namespace 'CISBenchmark' --alarm-actions <sns-topic-arn>

See Also

https://workbench.cisecurity.org/benchmarks/19631

Item Details

Category: AUDIT AND ACCOUNTABILITY

References: 800-53|AU-3, 800-53|AU-3(1), 800-53|AU-6, 800-53|AU-6(1), 800-53|AU-7, 800-53|AU-7(1), 800-53|AU-12, CSCv7|5.5, CSCv7|6.3

Plugin: amazon_aws

Control ID: d0fff6bb66a272f28a6be6eb6734e7f305bd119692e8fde8c392d67884daf56e