CloudWatch Changes To NACL Alarm Missing

• Query id: 0a8e8dc5-b6fc-44fc-b5a1-969ec950f9b0
• Query name: CloudWatch Changes To NACL Alarm Missing
• Platform: Terraform
• Severity: Medium
• Category: Observability
• CWE: 778
• URL: Github

Description

Ensure a log metric filter and alarm exist for changes to NACL
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

provider "aws" {
  region = "us-east-2"
}

resource "aws_cloudwatch_log_group" "CIS_CloudWatch_LogsGroup" {
  name = "CIS_CloudWatch_LogsGroup"
}

resource "aws_sns_topic" "cis_alerts_sns_topic" {
  name = "cis-alerts-sns-topic"
}

resource "aws_cloudwatch_metric_alarm" "cis_changes_nacl" {
  alarm_name                = "CIS-4.11-Changes-NACL"
  comparison_operator       = "GreaterThanOrEqualToThreshold"
  evaluation_periods        = "1"
  metric_name               = "OTHER FILTER"
  namespace                 = "CIS_Metric_Alarm_Namespace"
  period                    = "300"
  statistic                 = "Sum"
  threshold                 = "1"
  alarm_actions             = [aws_sns_topic.cis_alerts_sns_topic.arn]
  insufficient_data_actions = []
}

resource "aws_cloudwatch_log_metric_filter" "cis_changes_nacl" {
  name           = "CIS-4.11-Changes-NACL"
  pattern        = "{ ($.eventName = CreateNetworkAcl) || ($.eventName = CreateNetworkAclEntry) || ($.eventName = DeleteNetworkAcl) || ($.eventName = DeleteNetworkAclEntry) || ($.eventName = ReplaceNetworkAclEntry) || ($.eventName = ReplaceNetworkAclAssociation) }"
  log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name

  metric_transformation {
    name      = "CIS-4.11-Changes-NACL"
    namespace = "CIS_Metric_Alarm_Namespace"
    value     = "1"
  }
}

Positive test num. 2 - tf file

provider "aws" {
  region = "us-east-2"
}

resource "aws_cloudwatch_log_group" "CIS_CloudWatch_LogsGroup" {
  name = "CIS_CloudWatch_LogsGroup"
}

resource "aws_sns_topic" "cis_alerts_sns_topic" {
  name = "cis-alerts-sns-topic"
}

resource "aws_cloudwatch_metric_alarm" "cis_changes_nacl" {
  alarm_name                = "CIS-4.11-Changes-NACL"
  comparison_operator       = "GreaterThanOrEqualToThreshold"
  evaluation_periods        = "1"
  metric_name               = aws_cloudwatch_log_metric_filter.cis_changes_nacl.id
  namespace                 = "CIS_Metric_Alarm_Namespace"
  period                    = "300"
  statistic                 = "Sum"
  threshold                 = "1"
  alarm_actions             = [aws_sns_topic.cis_alerts_sns_topic.arn]
  insufficient_data_actions = []
}

resource "aws_cloudwatch_log_metric_filter" "cis_changes_nacl" {
  name           = "CIS-4.11-Changes-NACL"
  pattern        = "{ ($.eventName = CreateNetworkAclEntry) || ($.eventName = DeleteNetworkAcl) || ($.eventName = DeleteNetworkAclEntry) || ($.eventName = ReplaceNetworkAclEntry) || ($.eventName = ReplaceNetworkAclAssociation) }"
  log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name

  metric_transformation {
    name      = "CIS-4.11-Changes-NACL"
    namespace = "CIS_Metric_Alarm_Namespace"
    value     = "1"
  }
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

provider "aws" {
  region = "us-east-2"
}

resource "aws_cloudwatch_log_group" "CIS_CloudWatch_LogsGroup" {
  name = "CIS_CloudWatch_LogsGroup"
}

resource "aws_sns_topic" "cis_alerts_sns_topic" {
  name = "cis-alerts-sns-topic"
}

resource "aws_cloudwatch_metric_alarm" "cis_changes_nacl" {
  alarm_name                = "CIS-4.11-Changes-NACL"
  comparison_operator       = "GreaterThanOrEqualToThreshold"
  evaluation_periods        = "1"
  metric_name               = aws_cloudwatch_log_metric_filter.cis_changes_nacl.id
  namespace                 = "CIS_Metric_Alarm_Namespace"
  period                    = "300"
  statistic                 = "Sum"
  threshold                 = "1"
  alarm_actions             = [aws_sns_topic.cis_alerts_sns_topic.arn]
  insufficient_data_actions = []
}

resource "aws_cloudwatch_log_metric_filter" "cis_changes_nacl" {
  name           = "CIS-4.11-Changes-NACL"
  pattern        = "{ ($.eventName = CreateNetworkAcl) || ($.eventName = CreateNetworkAclEntry) || ($.eventName = DeleteNetworkAcl) || ($.eventName = DeleteNetworkAclEntry) || ($.eventName = ReplaceNetworkAclEntry) || ($.eventName = ReplaceNetworkAclAssociation) }"
  log_group_name = aws_cloudwatch_log_group.CIS_CloudWatch_LogsGroup.name

  metric_transformation {
    name      = "CIS-4.11-Changes-NACL"
    namespace = "CIS_Metric_Alarm_Namespace"
    value     = "1"
  }
}