Ensure there is a CloudWatch alarm set up in your AWS account that is triggered each time a Network Access Control List (NACL) configuration change is made. This CloudWatch alarm must fire every time an AWS API call is performed to create, update or delete a Network ACL.
This rule can help you with the following compliance standards:
- CISAWSF
- PCI
- APRA
- MAS
- NIST4
For further details on compliance standards supported by Conformity, see here.
This rule can help you work with the AWS Well-Architected Framework.
This rule resolution is part of the Conformity Security & Compliance tool for AWS.
The Network ACLs provide an additional layer of defense for your Virtual Private Clouds (VPCs). Using CloudWatch alarms to detect any configuration changes involving Network ACLs will help you prevent unexpected inbound and/or outbound rule modifications that may lead to unrestricted access and increase the opportunities for Distributed Denial of Service (DDoS) attacks.
Note 1: For this rule Cloud Conformity assumes that the CloudTrail service is already enabled to stream event log data to CloudWatch within your AWS account, otherwise see this rule to enable AWS Cloudtrail – CloudWatch integration.
Note 2: You have also the option to implement this conformity rule with AWS CloudFormation. Download the required CloudFormation template from this URL and follow the AWS instructions available here.
Audit
To determine if there are any CloudWatch alarms set up to monitor AWS Network ACLs configuration changes within your AWS account, perform the following:
Remediation / Resolution
Step 1: Create a Simple Notification Service (SNS) topic and the necessary subscription to send email notifications whenever your Amazon CloudWatch alarm is triggered.
Remediation / Resolution
Step 2: Create the necessary metric filter and the CloudWatch alarm that will fire and send SNS notifications whenever an AWS Network ACL (NACL) configuration will change.
References
- AWS Documentation
- Amazon CloudWatch Concepts
- Creating CloudWatch Alarms for CloudTrail Events
- Create a Topic
- Subscribe to a Topic
- Using an AWS CloudFormation Template to Create CloudWatch Alarms
- AWS Command Line Interface (CLI) Documentation
- cloudwatch
- describe-alarms-for-metric
- put-metric-alarm
- put-metric-filter
- sns
- create-topic
- subscribe
- confirm-subscription