cis-aws-foundations-5-11

name	cis-aws-foundations-5.11
description	Ensure Network Access Control List (NACL) changes are monitored
category	cis-monitoring
version	7.0.0
author	cyberstrike-official
tags	["cis","aws","monitoring","cloudwatch","cloudtrail","metric-filters","alarms","nacl","network-acl","vpc"]
cis_id	5.11
cis_benchmark	CIS AWS Foundations Benchmark v7.0.0
tech_stack	["aws"]
cwe_ids	[]
chains_with	["cis-aws-foundations-4.1","cis-aws-foundations-4.2"]
prerequisites	[]
severity_boost	{}

Ensure Network Access Control List (NACL) changes are monitored

Description

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.

NACLs are used as a stateless packet filter to control ingress and egress traffic for subnets within a VPC. It is recommended that a metric filter and alarm be established for any changes made to NACLs.

Rationale

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.

Monitoring changes to NACLs will help ensure that AWS resources and services are not unintentionally exposed.

Impact

N/A

Audit Procedure

Using AWS CLI

If you are using CloudTrail trails and CloudWatch, perform the following to ensure that there is at least one active multi-region CloudTrail trail with the prescribed metric filters and alarms configured:

1. Identify the log group name that is configured for use with the active multi-region CloudTrail trail:

• List all CloudTrail trails:

aws cloudtrail describe-trails

• Identify multi-region CloudTrail trails: Trails with "IsMultiRegionTrail" set to true

• Note the value associated with "Name":<trail-name>

• Note the <trail-log-group-name> within the value associated with "CloudWatchLogsLogGroupArn"

  • Example: arn:aws:logs:<region>:<account-id>:log-group:<trail-log-group-name>:*

• Ensure the identified multi-region CloudTrail trail is active:

aws cloudtrail get-trail-status --name <trail-name>

• Ensure IsLogging is set to TRUE

• Ensure the identified multi-region CloudTrail trail captures all management events:

aws cloudtrail get-event-selectors --trail-name <trail-name>

• Ensure there is at least one event selector for a trail with IncludeManagementEvents set to and set to