AWS Security using organization CloudTrail

Published in

AVM Consulting Blog

5 min readJun 8, 2022

The Organization CloudTrail solution will create an Organization CloudTrail within the Organization Management Account that is encrypted with a Customer Managed KMS Key managed in the Audit Account and logs delivered to the Log Archive Account. An Organization CloudTrail logs all events for all AWS accounts in the AWS Organization.

When you create an organization trail, a trail with the name that you give it will be created in every AWS account that belongs to your organization. Users with CloudTrail permissions in member accounts will be able to see this trail when they log into the AWS CloudTrail console from their AWS accounts, or when they run AWS CLI commands such as describe-trail. However, users in member accounts will not have sufficient permissions to delete the organization trail, turn to log on or off, change what types of events are logged, or otherwise alter the organization trail in any way.

The solution default configuration deploys an Organization CloudTrail enabling only data events to avoid duplicating the existing AWS Control Tower CloudTrail, which has the management events enabled.

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 for configuring the AWS Organization CloudTrail within the management account.

1.3 Lambda Execution IAM Role

The AWS Lambda Function Role allows the AWS Lambda service to assume the role and perform actions defined in the attached IAM policies.

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 (14 days) and are encrypted with a CloudWatch Logs service managed encryption key.

1.5 Organization CloudTrail

AWS CloudTrail for all AWS Organization accounts
Member accounts are automatically added and cannot modify
Data events can be disabled via the parameters
CloudWatch Logs can be disabled via the parameters

1.6 Organization CloudTrail CloudWatch Log Group Role

IAM role used to send CloudTrail logs to the CloudWatch log group

1.7 Organization CloudTrail CloudWatch Log Group

Contains the CloudTrail logs with a Retention (400 days)

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 stacks.

2.1 AWS CloudFormation

2.2 Organization CloudTrail KMS Key

Customer managed KMS key for the AWS Organizations CloudTrail logs and S3 server-side encryption

2.3 CloudTrail KMS Key Secret

AWS Secrets Manager secret containing the customer-managed KMS key ARN

3.0 Security Log Archive Account

3.1 AWS CloudFormation

See 1.1 AWS CloudFormation

3.2 Organization CloudTrail S3 Bucket

S3 bucket where the Organization CloudTrail logs are sent for all accounts in the AWS Organization

3.3 CloudTrail S3 Bucket Secret

AWS Secrets Manager secret containing the CloudTrail S3 bucket name

Implementation Instructions

Prerequisites

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

Solution Deployment

Choose a Deployment Method:

AWS CloudFormation
Customizations for AWS Control Tower

To enforce object encryption within the S3 bucket using the KMS key, add the following S3 bucket policy statements to the bucket created by the solution (e.g. sea-org-trail-logs-<account_id>-<aws_region>). The sea-cloud trail-org-bucket. yaml has the statements commented out and can be updated after the creation of the CloudTrail.

{ “Sid”: “DenyUnencryptedObjectUploads”, “Effect”: “Deny”, “Principal”: “*”, “Action”: “s3:PutObject”, “Resource”: “arn:aws:s3:::sra-org-trail-logs-<account_id>-<region>/*”, “Condition”: { “StringNotEquals”: { “s3:x-amz-server-side-encryption”: “aws:kms” } } }, { “Sid”: “DenyWrongKMSKey”, “Effect”: “Deny”, “Principal”: “*”, “Action”: “s3:PutObject”, “Resource”: “arn:aws:s3:::sra-org-trail-logs-<logging_account_id>-<region>/*”, “Condition”: { “StringNotEquals”: { “s3:x-amz-server-side-encryption-aws-kms-key-id”: “<bucket_encryption_key_arn>” } } }

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-cloud trail-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/cloudtrail/cloudtrail_org/templates/sra-cloudtrail-org-main-ssm.yaml — stack-name sra-cloudtrail-org-main-ssm — capabilities CAPABILITY_NAMED_IAM

Option 2: Use the sra-cloud trail-org-main. yaml template. Input is required for the CloudFormation parameters where the default is not set.

aws cloudformation deploy — template-file $HOME/aws-sra-examples/aws_sra_examples/solutions/cloudtrail/cloudtrail_org/templates/sra-cloudtrail-org-main.yaml — stack-name sra-cloudtrail-org-main — capabilities CAPABILITY_NAMED_IAM — parameter-overrides pAuditAccountId=<AUDIT_ACCOUNT_ID> pLogArchiveAccountId=<LOG_ARCHIVE_ACCOUNT_ID> pOrganizationId=<ORGANIZATION_ID> pSRAStagingS3BucketName=<SRA_STAGING_S3_BUCKET_NAME>

Verify Solution Deployment

Log into the management account and navigate to the CloudTrail page
Select Trails and select the sra-cloudtrail-org trail
Verify the correct configurations have been applied

Solution Delete Instructions

In the management account (home region), delete the AWS CloudFormation Stack (sra-cloudtrail-org-main-ssm or sra-cloudtrail-org-main) created above.
In the management account (home region), delete the AWS CloudWatch Log Group (e.g. /aws/lambda/<solution_name>) for the Lambda function deployed.
In the log archive acccount (home region), delete the S3 bucket (e.g. sra-org-trail-logs-<account_id>-<aws_region>) created by the solution.