#!/usr/bin/env bash

# Prowler - the handy cloud security tool (copyright 2019) by Toni de la Fuente
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy
# of the License at http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software distributed
# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
# CONDITIONS OF ANY KIND, either express or implied. See the License for the
# specific language governing permissions and limitations under the License.
#
# 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 IAMAuthConfigChanges \
#     --filter-pattern '{ ($.eventName = DeleteGroupPolicy) || ($.eventName = DeleteRolePolicy) || ($.eventName = DeleteUserPolicy) || ($.eventName = PutGroupPolicy) || ($.eventName = PutRolePolicy) || ($.eventName = PutUserPolicy) || ($.eventName = CreatePolicy) || ($.eventName = DeletePolicy) || ($.eventName = CreatePolicyVersion) || ($.eventName = DeletePolicyVersion) || ($.eventName = AttachRolePolicy) || ($.eventName = DetachRolePolicy) || ($.eventName = AttachUserPolicy) || ($.eventName = DetachUserPolicy) || ($.eventName = AttachGroupPolicy) || ($.eventName = DetachGroupPolicy) }' \
#     --metric-transformations metricName=IAMPolicyEventCount,metricNamespace=CloudTrailMetrics,metricValue=1
#
#   aws cloudwatch put-metric-alarm \
#     --region us-east-1 \
#     --alarm-name IAMAuthorizationActivityAlarm \
#     --alarm-description "Triggered by AWS IAM authorization config changes." \
#     --metric-name IAMPolicyEventCount \
#     --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_check34="3.4"
CHECK_TITLE_check34="[check34] Ensure a log metric filter and alarm exist for IAM policy changes (Scored)"
CHECK_SCORED_check34="SCORED"
CHECK_TYPE_check34="LEVEL1"
CHECK_SEVERITY_check34="Medium"
CHECK_ASFF_TYPE_check34="Software and Configuration Checks/Industry and Regulatory Standards/CIS AWS Foundations Benchmark"
CHECK_ASFF_RESOURCE_TYPE_check34="AwsCloudTrailTrail"
CHECK_ALTERNATE_check304="check34"
CHECK_ASFF_COMPLIANCE_TYPE_check34="ens-op.exp.8.aws.trail.6"
CHECK_SERVICENAME_check34="iam"
CHECK_RISK_check34='Monitoring unauthorized API calls will help reveal application errors and may reduce time to detect malicious activity.'
CHECK_REMEDIATION_check34='It is recommended that a metric filter and alarm be established for unauthorized requests.'
CHECK_DOC_check34='https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudwatch-alarms-for-cloudtrail.html'
CHECK_CAF_EPIC_check34='IAM'

check34(){
  check3x '\$\.eventName\s*=\s*DeleteGroupPolicy.+\$\.eventName\s*=\s*DeleteRolePolicy.+\$\.eventName\s*=\s*DeleteUserPolicy.+\$\.eventName\s*=\s*PutGroupPolicy.+\$\.eventName\s*=\s*PutRolePolicy.+\$\.eventName\s*=\s*PutUserPolicy.+\$\.eventName\s*=\s*CreatePolicy.+\$\.eventName\s*=\s*DeletePolicy.+\$\.eventName\s*=\s*CreatePolicyVersion.+\$\.eventName\s*=\s*DeletePolicyVersion.+\$\.eventName\s*=\s*AttachRolePolicy.+\$\.eventName\s*=\s*DetachRolePolicy.+\$\.eventName\s*=\s*AttachUserPolicy.+\$\.eventName\s*=\s*DetachUserPolicy.+\$\.eventName\s*=\s*AttachGroupPolicy.+\$\.eventName\s*=\s*DetachGroupPolicy'
}