For AI agents: A markdown version of this page is available at https://docs.datadoghq.com/security/code_security/iac_security/iac_rules/cloudformation-aws-cloudtrail-log-files-not-encrypted-with-kms.md. A documentation index is available at /llms.txt.

CloudTrail log files not encrypted with KMS

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Metadata

Id: cloudformation-aws-cloudtrail-log-files-not-encrypted-with-kms

Provider: AWS

Platform: CloudFormation

Severity: Low

Category: Encryption

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Description

CloudTrail log files must be encrypted with an AWS KMS customer-managed key to protect the confidentiality and integrity of audit logs and enable key access control and rotation.

The CloudFormation resource type AWS::CloudTrail::Trail must define the KMSKeyId property with a non-empty value (AWS KMS key ARN, key ID, alias, or a reference to an AWS::KMS::Key). Resources missing KMSKeyId or with it set to null or an empty string will be flagged.

Create or reference a customer-managed AWS KMS key and assign it to KMSKeyId (using !Ref, !GetAtt, or an ARN) so CloudTrail delivers logs encrypted under that key.

Secure CloudFormation example:

MyKmsKey:
  Type: AWS::KMS::Key
  Properties:
    Description: KMS key for CloudTrail log encryption

MyTrail:
  Type: AWS::CloudTrail::Trail
  Properties:
    IsLogging: true
    S3BucketName: my-trail-bucket
    KMSKeyId: !Ref MyKmsKey

Compliant Code Examples

AWSTemplateFormatVersion: "2010-09-09"
Parameters:
  OperatorEmail:
    Description: "Email address to notify when new logs are published."
    Type: String
Resources:
  S3Bucket:
    DeletionPolicy: Retain
    Type: AWS::S3::Bucket
    Properties: {}
  BucketPolicy:
    Type: AWS::S3::BucketPolicy
    Properties:
      Bucket:
        Ref: S3Bucket
      PolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Sid: "AWSCloudTrailAclCheck"
            Effect: "Allow"
            Principal:
              Service: "cloudtrail.amazonaws.com"
            Action: "s3:GetBucketAcl"
            Resource: !Sub |-
              arn:aws:s3:::${S3Bucket}
          - Sid: "AWSCloudTrailWrite"
            Effect: "Allow"
            Principal:
              Service: "cloudtrail.amazonaws.com"
            Action: "s3:PutObject"
            Resource: !Sub |-
              arn:aws:s3:::${S3Bucket}/AWSLogs/${AWS::AccountId}/*
            Condition:
              StringEquals:
                s3:x-amz-acl: "bucket-owner-full-control"
  Topic:
    Type: AWS::SNS::Topic
    Properties:
      Subscription:
        - Endpoint:
            Ref: OperatorEmail
          Protocol: email
  TopicPolicy:
    Type: AWS::SNS::TopicPolicy
    Properties:
      Topics:
        - Ref: "Topic"
      PolicyDocument:
        Version: "2008-10-17"
        Statement:
          - Sid: "AWSCloudTrailSNSPolicy"
            Effect: "Allow"
            Principal:
              Service: "cloudtrail.amazonaws.com"
            Resource: "*"
            Action: "SNS:Publish"
  myTrail:
    DependsOn:
      - BucketPolicy
      - TopicPolicy
    Type: AWS::CloudTrail::Trail
    Properties:
      KMSKeyId: arn:aws:kms:us-east-2:123456789012:key/12345678-1234-1234-1234-123456789012
      S3BucketName:
        Ref: S3Bucket
      SnsTopicName:
        Fn::GetAtt:
          - Topic
          - TopicName
      IsLogging: true
      IsMultiRegionTrail: true

Non-Compliant Code Examples

AWSTemplateFormatVersion: "2010-09-09"
Parameters:
  OperatorEmail:
    Description: "Email address to notify when new logs are published."
    Type: String
Resources:
  S3Bucket:
    DeletionPolicy: Retain
    Type: AWS::S3::Bucket
    Properties: {}
  BucketPolicy:
    Type: AWS::S3::BucketPolicy
    Properties:
      Bucket:
        Ref: S3Bucket
      PolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Sid: "AWSCloudTrailAclCheck"
            Effect: "Allow"
            Principal:
              Service: "cloudtrail.amazonaws.com"
            Action: "s3:GetBucketAcl"
            Resource: !Sub |-
              arn:aws:s3:::${S3Bucket}
          - Sid: "AWSCloudTrailWrite"
            Effect: "Allow"
            Principal:
              Service: "cloudtrail.amazonaws.com"
            Action: "s3:PutObject"
            Resource: !Sub |-
              arn:aws:s3:::${S3Bucket}/AWSLogs/${AWS::AccountId}/*
            Condition:
              StringEquals:
                s3:x-amz-acl: "bucket-owner-full-control"
  Topic:
    Type: AWS::SNS::Topic
    Properties:
      Subscription:
        - Endpoint:
            Ref: OperatorEmail
          Protocol: email
  TopicPolicy:
    Type: AWS::SNS::TopicPolicy
    Properties:
      Topics:
        - Ref: "Topic"
      PolicyDocument:
        Version: "2008-10-17"
        Statement:
          - Sid: "AWSCloudTrailSNSPolicy"
            Effect: "Allow"
            Principal:
              Service: "cloudtrail.amazonaws.com"
            Resource: "*"
            Action: "SNS:Publish"
  myTrail:
    DependsOn:
      - BucketPolicy
      - TopicPolicy
    Type: AWS::CloudTrail::Trail
    Properties:
      S3BucketName:
        Ref: S3Bucket
      SnsTopicName:
        Fn::GetAtt:
          - Topic
          - TopicName
      IsLogging: true
      IsMultiRegionTrail: true