firewall_manager_org

Firewall Manager

Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. SPDX-License-Identifier: CC-BY-SA-4.0

Table of Contents

• Introduction
• Deployed Resource Details
• Implementation Instructions
• References

Introduction

The Organization Firewall Manager solution will delegate an administrator account (e.g. Audit Account), deploy a maximum allowed security group, configure a security group policy, and configure multiple WAF policies.

AWS Firewall Manager simplifies your AWS WAF, AWS Shield Advanced, and Amazon VPC security groups administration and maintenance tasks across multiple accounts and resources. With Firewall Manager, you set up your AWS WAF firewall rules, Shield Advanced protections, and Amazon VPC security groups just once. Firewall Manager is particularly useful when you want to protect your entire organization rather than a few number of specific accounts and resources, or if you frequently add new resources that you want to protect. To use Firewall Manager, your account must be a member of an organization in the AWS Organizations service, and you must enable AWS Config for each member account in your AWS Organization.

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Deployed Resource Details

1.0 Organization Management Account

1.1 AWS CloudFormation

• All resources are deployed via AWS CloudFormation as a StackSet and Stack Instance within the management account or a CloudFormation Stack within a specific account.
• The Customizations for AWS Control Tower solution deploys all templates as a CloudFormation StackSet.
• For parameter details, review the AWS CloudFormation templates.

1.2 AWS Lambda Function

The Lambda function contains logic to associate a delegated administrator account for Firewall Manager

1.3 Lambda Execution IAM Role

• IAM role used by the Lambda function to configure the Firewall Delegated Administrator Account

1.4 Lambda CloudWatch Log Group

• All the AWS Lambda Function logs are sent to a CloudWatch Log Group </aws/lambda/<LambdaFunctionName> to help with debugging and traceability of the actions performed.
• By default the AWS Lambda Function will create the CloudWatch Log Group with a Retention (Never expire) and are encrypted with a CloudWatch Logs service managed encryption key.

1.5 Firewall Manager

• Firewall Manager APIs are used to delegate an administrator account. Once the delegated administrator account is allocated, Firewall Manager can take a few minutes to activate all accounts and regions.
• The Lambda function has built in wait times (e.g. 5 minutes) to help avoid errors when configuring Firewall Manager with security policies.

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2.0 Audit Account

The example solutions use Audit Account instead of Security Tooling Account to align with the default account name used within the AWS Control Tower setup process for the Security Account. The Account ID for the Audit Account SSM parameter is populated from the SecurityAccountId parameter within the AWSControlTowerBP-BASELINE-CONFIG StackSet.

2.1 AWS CloudFormation

• See 1.1 AWS CloudFormation

2.2 VPC and Security Group

• A security group is used by the Firewall Manager security group policy to define the maximum allowed rules.

• A VPC is required for creating the security group.

• Using AWS Firewall Manager to audit VPC Security Groups:

  • AWS Firewall Manager enables the ability to audit (and remediate - if desired) security groups across the AWS Organization Unit. This solution utilizes Content Audit Security Group Policies to verify that Security Groups created across the AWS Organization Unit adhere to the rules.
  • A Usage Audit Security Group Policy is used to identify and remediate unused security groups to keep proper hygiene in the target accounts.

• Security Group Policies:

  • Firewall Manager Security Group Content Audit Policy
    • This Security Group Policy utilizes a provided security group to audit against 2 rules:
      • The only protocol that can ever allow inbound traffic is TCP/443 (HTTPS)
      • All other protocols are allowed internally to the CIDR blocks for the VPC Networks
  • Firewall Manager Unused Security Group Policy
    • This Security Group policy specifically targets unused Security groups.
    • If remediation is enabled, Firewall Manager will automatically clean up security groups that are not actively being used to maintain good hygiene in the AWS environment.

2.3 Firewall Manager

• This solution utilizes AWS Firewall Manager to deploy a baseline set of AWS Managed WAF Rules to monitor and remediate the configured resources within the AWS Organization.

• Firewall Manager WAF Policies allow Firewall Manager to centrally mandate the application of AWS WAF Rule sets and Web ACLs to endpoints (ELBs, CloudFront Distributions, and API Gateway) in the environment.

• The solution enforces the policies based on resource tags, which can be enforced using an IAM or SCP policy.

• WAF Policies:

  • FMS Regional WAF Default Policy
    • Resource Types
      • ELBv2
    • API Gateway
    • AWS Managed Rule sets
      • AWS Core Ruleset
      • AWS SQL Database Ruleset
      • AWS IP Reputation List
    • Resource Tag
      • Key: fms-default-policy
      • Value: true
  • FMS CloudFront Default Policy
    • Resource Types
      • Cloudfront Distribution
    • AWS Managed Rule sets
      • AWS Core Ruleset
      • AWS SQL Database Ruleset
      • AWS IP Reputation List
    • Resource Tag
      • Key: fms-default-policy
      • Value: true
  • FMS Regional WAF Windows Policy
    • Resource Types
      • ELBv2
      • API Gateway
    • AWS Managed Rule sets
      • AWS Core Ruleset
      • AWS Windows Operating System Ruleset
    • Resource Tag
      • Key: workload-os
      • Value: windows
  • FMS Regional WAF Linux Policy
    • Resource Types
      • ELBv2
      • API Gateway
    • AWS Managed Rule sets
      • AWS Core Ruleset
      • AWS Linux Operating System Ruleset
    • Resource Tag
      • Key: workload-os
      • Value: linux
  • FMS Regional WAF Posix Policy
    • Resource Types
      • ELBv2
      • API Gateway
    • AWS Managed Rule sets
      • AWS Core Ruleset
      • AWS Posix Operating System Ruleset
    • Resource Tag
      • Key: workload-os
      • Value: posix

2.4 Firewall Manager Disassociate IAM Role

• The Firewall Manager Disassociate IAM role is deployed to the delegated administrator account to disassociate the account from Firewall Manager when the solution is deleted.
• Firewall Manager requires the disassociation to happen within the delegated administrator account. The management account Lambda function assumes this role to disassociate the account when the custom resource is deleted via CloudFormation.
• The disassociation process can take about 15 minutes before allowing another delegated administrator account association.

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Implementation Instructions

Prerequisites

1. Download and Stage the SRA Solutions. Note: This only needs to be done once for all the solutions.
2. Verify that the SRA Prerequisites Solution has been deployed.

Solution Deployment

Choose a Deployment Method:

• AWS CloudFormation
• Customizations for AWS Control Tower

AWS CloudFormation

In the management account (home region), launch an AWS CloudFormation Stack using one of the options below:

• Option 1: (Recommended) Use the sra-firewall-manager-org-main-ssm.yaml template. This is a more automated approach where some of the CloudFormation parameters are populated from SSM parameters created by the SRA Prerequisites Solution.

  aws cloudformation deploy --template-file $HOME/aws-sra-examples/aws_sra_examples/solutions/firewall_manager/firewall_manager_org/templates/sra-firewall-manager-org-main-ssm.yaml --stack-name sra-firewall-manager-org-main-ssm --capabilities CAPABILITY_NAMED_IAM --parameter-overrides pInternalNetCIDR=<INTERNAL_NET_CIDR>

• Option 2: Use the sra-firewall-manager-org-main.yaml template. Input is required for the CloudFormation parameters where the default values are not set.

  aws cloudformation deploy --template-file $HOME/aws-sra-examples/aws_sra_examples/solutions/firewall_manager/firewall_manager_org/templates/sra-firewall-manager-org-main.yaml --stack-name sra-firewall-manager-org-main --capabilities CAPABILITY_NAMED_IAM --parameter-overrides pDelegatedAdminAccountId=<DELEGATED_ADMIN_ACCOUNT_ID> pInternalNetCIDR=<INTERNAL_NET_CIDR> pSRAStagingS3BucketName=<SRA_STAGING_S3_BUCKET_NAME>

Verify Solution Deployment

1. Log into the Delegated Admin Account (eg. Audit account) and navigate to the AWS Firewall Manager page
2. Verify the correct configurations have been applied
   1. Security policies
      • security-group-maximum-allowed
      • security-group-common-policy
      • fms-regional-waf-default-policy
      • fms-regional-waf-windows-policy
      • fms-regional-waf-linux-policy
      • fms-regional-waf-posix-policy

Solution Delete Instructions

1. In the management account (home region), delete the AWS CloudFormation Stack created in the solution deployment.
2. In the management account (home region), delete the AWS CloudWatch Log Group (e.g. /aws/lambda/<solution_name>) for the Lambda function.

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References

• Firewall Manager Developer Guide
• Firewall Manager WAF Policies
• Firewall Manager Security Group Policy Usage