#!/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 S3BucketConfigChanges \
#     --filter-pattern '{ ($.eventSource = s3.amazonaws.com) && (($.eventName = PutBucketAcl) || ($.eventName = PutBucketPolicy) || ($.eventName = PutBucketCors) || ($.eventName = PutBucketLifecycle) || ($.eventName = PutBucketReplication) || ($.eventName = DeleteBucketPolicy) || ($.eventName = DeleteBucketCors) || ($.eventName = DeleteBucketLifecycle) || ($.eventName = DeleteBucketReplication)) }' \
#     --metric-transformations metricName=S3BucketEventCount,metricNamespace=CloudTrailMetrics,metricValue=1
#
#   aws cloudwatch put-metric-alarm \
#     --region us-east-1 \
#     --alarm-name S3BucketConfigChangesAlarm \
#     --alarm-description "Triggered by AWS S3 Bucket config changes." \
#     --metric-name S3BucketEventCount \
#     --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_check38="3.8"
CHECK_TITLE_check38="[check38] Ensure a log metric filter and alarm exist for S3 bucket policy changes (Scored)"
CHECK_SCORED_check38="SCORED"
CHECK_TYPE_check38="LEVEL1"
CHECK_SEVERITY_check38="Medium"
CHECK_ASFF_TYPE_check38="Software and Configuration Checks/Industry and Regulatory Standards/CIS AWS Foundations Benchmark"
CHECK_ASFF_RESOURCE_TYPE_check38="AwsCloudTrailTrail"
CHECK_ALTERNATE_check308="check38"
CHECK_SERVICENAME_check38="s3"

check38(){
  check3x '\$\.eventSource\s*=\s*s3.amazonaws.com.+\$\.eventName\s*=\s*PutBucketAcl.+\$\.eventName\s*=\s*PutBucketPolicy.+\$\.eventName\s*=\s*PutBucketCors.+\$\.eventName\s*=\s*PutBucketLifecycle.+\$\.eventName\s*=\s*PutBucketReplication.+\$\.eventName\s*=\s*DeleteBucketPolicy.+\$\.eventName\s*=\s*DeleteBucketCors.+\$\.eventName\s*=\s*DeleteBucketLifecycle.+\$\.eventName\s*=\s*DeleteBucketReplication'
}