#!/usr/bin/env bash

# Prowler - the handy cloud security tool (c) by Toni de la Fuente
#
# This Prowler check is licensed under a
# Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
#
# You should have received a copy of the license along with this
# work. If not, see <http://creativecommons.org/licenses/by-nc-sa/4.0/>.
#
# Remediation:
#
#   https://d1.awsstatic.com/whitepapers/compliance/AWS_CIS_Foundations_Benchmark.pdf
#
#   aws logs put-metric-filter \
#     --region us-east-1 \
#     --log-group-name CloudTrail/CloudWatchLogGroup \
#     --filter-name VPCGatewayConfigChanges \
#     --filter-pattern '{ ($.eventName = CreateCustomerGateway) || ($.eventName = DeleteCustomerGateway) || ($.eventName = AttachInternetGateway) || ($.eventName = CreateInternetGateway) || ($.eventName = DeleteInternetGateway) || ($.eventName = DetachInternetGateway) }' \
#     --metric-transformations metricName=GatewayEventCount,metricNamespace=CloudTrailMetrics,metricValue=1
#
#   aws cloudwatch put-metric-alarm \
#     --region us-east-1 \
#     --alarm-name VPCGatewayConfigChangesAlarm \
#     --alarm-description "Triggered by VPC Customer/Internet Gateway changes." \
#     --metric-name GatewayEventCount \
#     --namespace CloudTrailMetrics \
#     --statistic Sum \
#     --comparison-operator GreaterThanOrEqualToThreshold \
#     --evaluation-periods 1 \
#     --period 300 \
#     --threshold 1 \
#     --actions-enabled \
#     --alarm-actions arn:aws:sns:us-east-1:123456789012:CloudWatchAlarmTopic

CHECK_ID_check312="3.12"
CHECK_TITLE_check312="[check312] Ensure a log metric filter and alarm exist for changes to network gateways (Scored)"
CHECK_SCORED_check312="SCORED"
CHECK_TYPE_check312="LEVEL1"
CHECK_SEVERITY_check312="Medium"
CHECK_ASFF_TYPE_check312="Software and Configuration Checks/Industry and Regulatory Standards/CIS AWS Foundations Benchmark"
CHECK_ASFF_RESOURCE_TYPE_check312="AwsCloudTrailTrail"
CHECK_ALTERNATE_check312="check312"
CHECK_SERVICENAME_check312="vpc"
CHECK_RISK_check312='Monitoring unauthorized API calls will help reveal application errors and may reduce time to detect malicious activity.'
CHECK_REMEDIATION_check312='It is recommended that a metric filter and alarm be established for unauthorized requests.'
CHECK_DOC_check312='https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudwatch-alarms-for-cloudtrail.html'
CHECK_CAF_EPIC_check312='Logging and Monitoring'

check312(){
  check3x '\$\.eventName\s*=\s*CreateCustomerGateway.+\$\.eventName\s*=\s*DeleteCustomerGateway.+\$\.eventName\s*=\s*AttachInternetGateway.+\$\.eventName\s*=\s*CreateInternetGateway.+\$\.eventName\s*=\s*DeleteInternetGateway.+\$\.eventName\s*=\s*DetachInternetGateway'
}