For AI agents: A markdown version of this page is available at https://docs.datadoghq.com/security/code_security/iac_security/iac_rules/terraform-aws-cloudwatch-network-gateways-changes-alarm-missing.md. A documentation index is available at /llms.txt.

CloudWatch network gateways changes alarm missing

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Metadata

Id: terraform-aws-cloudwatch-network-gateways-changes-alarm-missing

Provider: AWS

Platform: Terraform

Severity: Low

Category: Observability

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Description

This control checks that a log metric filter and an associated alarm are set up to monitor changes to network gateways in AWS, such as creation or deletion of customer or internet gateways. If the metric_name attribute in the aws_cloudwatch_metric_alarm resource is not correctly set to the name of the log metric filter (for example, "XXXX NOT YOUR FILTER XXXX"), gateway modifications may go undetected. Without this alerting, unauthorized or unintended changes to network gateways can occur without notice, potentially exposing the VPC to security risks or data exfiltration.

Compliant Code Examples

resource "aws_cloudwatch_log_metric_filter" "cis_network_gateway_changes_metric_filter" {
  name           = "CIS-NetworkGatewayChanges"
  pattern        = "{ ($.eventName = CreateCustomerGateway) || ($.eventName = DeleteCustomerGateway) || ($.eventName = AttachInternetGateway) || ($.eventName = CreateInternetGateway) || ($.eventName = DeleteInternetGateway) || ($.eventName = DetachInternetGateway) }"
  log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name

  metric_transformation {
    name      = "CIS-NetworkGatewayChanges"
    namespace = "CIS_Metric_Alarm_Namespace"
    value     = "1"
  }
}
resource "aws_cloudwatch_metric_alarm" "cis_network_gateway_changes_cw_alarm" {
  alarm_name                = "CIS-3.12-NetworkGatewayChanges"
  comparison_operator       = "GreaterThanOrEqualToThreshold"
  evaluation_periods        = "1"
  metric_name               = aws_cloudwatch_log_metric_filter.cis_network_gateway_changes_metric_filter.id
  namespace                 = "CIS_Metric_Alarm_Namespace"
  period                    = "300"
  statistic                 = "Sum"
  threshold                 = "1"
  alarm_description         = "Monitoring changes to network gateways will help ensure that all ingress/egress traffic traverses the VPC border via a controlled path."
  alarm_actions             = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
  insufficient_data_actions = []
}

Non-Compliant Code Examples

resource "aws_cloudwatch_log_metric_filter" "cis_network_gateway_changes_metric_filter" {
  name           = "CIS-NetworkGatewayChanges"
  pattern        = "{ ($.eventName = CreateCustomerGateway) || ($.eventName = DeleteCustomerGateway) || ($.eventName = AttachInternetGateway) || ($.eventName = CreateInternetGateway) || ($.eventName = DeleteInternetGateway) || ($.eventName = DetachInternetGateway) }"
  log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name

  metric_transformation {
    name      = "CIS-NetworkGatewayChanges"
    namespace = "CIS_Metric_Alarm_Namespace"
    value     = "1"
  }
}
resource "aws_cloudwatch_metric_alarm" "cis_network_gateway_changes_cw_alarm" {
  alarm_name                = "CIS-3.12-NetworkGatewayChanges"
  comparison_operator       = "GreaterThanOrEqualToThreshold"
  evaluation_periods        = "1"
  metric_name               = "XXXX NOT YOUR FILTER XXXX"
  namespace                 = "CIS_Metric_Alarm_Namespace"
  period                    = "300"
  statistic                 = "Sum"
  threshold                 = "1"
  alarm_description         = "Monitoring changes to network gateways will help ensure that all ingress/egress traffic traverses the VPC border via a controlled path."
  alarm_actions             = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
  insufficient_data_actions = []
}

resource "aws_cloudwatch_log_metric_filter" "cis_unauthorized_api_calls_metric_filter" {
  name           = "CIS-UnauthorizedAPICalls"
  pattern        = "{ ($.errorCode = \"*UnauthorizedOperation\") || ($.errorCode = \"AccessDenied*\") }"
  log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name

  metric_transformation {
    name      = "CIS-UnauthorizedAPICalls"
    namespace = "CIS_Metric_Alarm_Namespace"
    value     = "1"
  }
}

resource "aws_cloudwatch_metric_alarm" "cis_unauthorized_api_calls_cw_alarm" {
  alarm_name                = "CIS-3.1-UnauthorizedAPICalls"
  comparison_operator       = "GreaterThanOrEqualToThreshold"
  evaluation_periods        = "1"
  metric_name               = aws_cloudwatch_log_metric_filter.cis_unauthorized_api_calls_metric_filter.id
  namespace                 = "CIS_Metric_Alarm_Namespace"
  period                    = "300"
  statistic                 = "Sum"
  threshold                 = "1"
  alarm_description         = "Monitoring unauthorized API calls will help reveal application errors and may reduce time to detect malicious activity."
  alarm_actions             = [aws_sns_topic.cis_alerts_sns_topic.arn]
  insufficient_data_actions = []
}

resource "aws_cloudwatch_log_metric_filter" "cis_network_gateway_changes_metric_filter" {
  name           = "CIS-NetworkGatewayChanges"
  pattern        = "{ ($.eventName = CreateCustomerGateway) || ($.eventName = DetachInternetGateway) }"
  log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name

  metric_transformation {
    name      = "CIS-NetworkGatewayChanges"
    namespace = "CIS_Metric_Alarm_Namespace"
    value     = "1"
  }
}
resource "aws_cloudwatch_metric_alarm" "cis_network_gateway_changes_cw_alarm" {
  alarm_name                = "CIS-3.12-NetworkGatewayChanges"
  comparison_operator       = "GreaterThanOrEqualToThreshold"
  evaluation_periods        = "1"
  metric_name               = aws_cloudwatch_log_metric_filter.cis_network_gateway_changes_metric_filter.id
  namespace                 = "CIS_Metric_Alarm_Namespace"
  period                    = "300"
  statistic                 = "Sum"
  threshold                 = "1"
  alarm_description         = "Monitoring changes to network gateways will help ensure that all ingress/egress traffic traverses the VPC border via a controlled path."
  alarm_actions             = [aws_sns_topic.CIS_Alerts_SNS_Topic.arn]
  insufficient_data_actions = []
}