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How to Find AWS VPCs Without EC2 Flow Logging Enabled

VPC Flow Logs provide visibility into network traffic that traverses the VPC and can be used to detect anomalous traffic or insight during security workflows.

info

This security check is part of the CIS Amazon Web Services Benchmarks and is rated severity medium.

Prerequisites​

This guide assumes that you have already installed and configured Fix Inventory to collect your AWS resources.

Directions​

  1. Execute the following search command in Fix Inventory Shell:

    > search is(aws_vpc) with(empty, --> is(aws_ec2_flow_log))
    ​kind=aws_vpc, ..., region=fixinventory-poweruser
    ​kind=aws_vpc, ..., account=poweruser-team

  2. Pipe the search command into the dump command:

    > search is(aws_vpc) with(empty, --> is(aws_ec2_flow_log)) | dump
    ​reported:
    ​  id: /aws/ec2/123
    ​  name: some-name
    ​  ctime: '2022-12-05T22:53:14Z'
    ​  kind: aws_vpc
    ​  age: 2mo28d

    The command output will list the details of all non-compliant aws_vpc resources.

Remediation​

Enable Flow Logs for packet Rejects of your VPCs.

note

Please refer to the AWS EC2 documentation for details.

Further Reading​