GuardDuty 全リージョン分の検出結果を EventBridge で集約してからメール通知する CloudFormation テンプレートの紹介

AWSTemplateFormatVersion: "2010-09-09"

Parameters:
  ProjectName:
    Description: Project Name
    Type: String
    Default: unnamed

Resources:
  # ------------------------------------------------------------#
  # EventBridge
  # ------------------------------------------------------------#
  # Custom Event Bus
  EventsEventBus1:
    Type: "AWS::Events::EventBus"
    Properties:
      Name: !Sub ${ProjectName}-eventbus-receiver

  # Event Rule
  EventsRule1:
    Type: "AWS::Events::Rule"
    Properties:
      Name: !Sub ${ProjectName}-receiver-rule
      EventBusName: !Ref EventsEventBus1
      Targets:
        - Arn: !Ref SNSTopic1
          Id: "NotificationDestinationTopic"
          InputTransformer:
            InputPathsMap:
              Account_ID: "$.detail.accountId"
              Finding_ID: "$.detail.id"
              Finding_Type: "$.detail.type"
              Finding_description: "$.detail.description"
              Resource_Type: "$.detail.resource.resourceType"
              region: "$.region"
              severity: "$.detail.severity"
            InputTemplate: |
              "AWS <Account_ID> has a severity <severity> GuardDuty finding type <Finding_Type> in the <region> region."
              "Resource_Type:<Resource_Type>"
              "Finding Description:"
              "<Finding_description>. "
              "For more details open the GuardDuty console at https://<region>.console.aws.amazon.com/guardduty/home?region=<region>#/findings?search=id%3D<Finding_ID>&macros=current"
      EventPattern: |
        {
            "source": [
                "aws.guardduty"
            ],
            "detail-type": [
                "GuardDuty Finding"
            ],
            "detail": {
                "severity": [
                    { "numeric": [ ">=", 0 ] }
                ]
            }
        }
  # ------------------------------------------------------------#
  # SNS
  # ------------------------------------------------------------#
  SNSTopic1:
    Type: "AWS::SNS::Topic"
    Properties:
      DisplayName: !Sub ${ProjectName}-receiver-topic
      TopicName: !Sub ${ProjectName}-receiver-topic
  SNSTopicPolicy1:
    Type: "AWS::SNS::TopicPolicy"
    Properties:
      Topics:
        - !Ref SNSTopic1
      PolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Sid: "EventBridgeRule"
            Effect: "Allow"
            Principal:
              Service: "events.amazonaws.com"
            Action: "sns:Publish"
            Resource: !Ref SNSTopic1

  # ------------------------------------------------------------#
  # Sender for IAM Role
  # ------------------------------------------------------------#
  IAMRole1:
    Type: "AWS::IAM::Role"
    Properties:
      Path: "/service-role/"
      RoleName: !Sub ${ProjectName}-eventbridge-role
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service: "events.amazonaws.com"
            Action: "sts:AssumeRole"
      MaxSessionDuration: 3600
      ManagedPolicyArns:
        - !Ref IAMManagedPolicy1
  IAMManagedPolicy1:
    Type: "AWS::IAM::ManagedPolicy"
    Properties:
      ManagedPolicyName: !Sub ${ProjectName}-eventbridge-policy
      Path: "/service-role/"
      PolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Action:
              - "events:PutEvents"
            Resource:
              - !GetAtt EventsEventBus1.Arn

Outputs:
  ReceiverCustomEventBusARNOutput:
    Description: "This value is used in the stack set  parameters."
    Value: !GetAtt EventsEventBus1.Arn
    Export:
      Name: !Sub ${AWS::StackName}-ReceiverCustomEventBusARN
  SenderRoleARNOutput:
    Description: "This value is used in the stack set  parameters."
    Value: !GetAtt IAMRole1.Arn
    Export:
      Name: !Sub ${AWS::StackName}-SenderRoleARN

AWSTemplateFormatVersion: "2010-09-09"

Parameters:
  ProjectName:
    Description: Project Name
    Type: String
    Default: unnamed
  ReceiverCustomEventBusARN:
    Description: "Enter the value of the output of the receiver stack"
    Type: String
    Default: arn:aws:events:ap-northeast-1:123456789012:event-bus/project-eventbus-receiver
  SenderRoleARN:
    Description: "Enter the value of the output of the receiver stack"
    Type: String
    Default: arn:aws:iam::123456789012:role/service-role/project-eventbridge-role

Resources:
  # ------------------------------------------------------------#
  # EventBridge
  # ------------------------------------------------------------#
  # Event Rule
  EventsRule1:
    Type: "AWS::Events::Rule"
    Properties:
      Name: !Sub ${ProjectName}-sender-rule
      EventBusName: "default"
      Targets:
        - Arn: !Ref ReceiverCustomEventBusARN
          Id: "EventBridgeSender"
          RoleArn: !Ref SenderRoleARN
      EventPattern: |
        {
            "source": [
                "aws.guardduty"
            ],
            "detail-type": [
                "GuardDuty Finding"
            ]
        }