#!/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/MyCloudTrailLG \
#     --filter-name AWSAuthorizationFailures \
#     --filter-pattern '{ $.errorCode = "*UnauthorizedOperation" || $.errorCode = "AccessDenied*" }' \
#     --metric-transformations metricName=AuthorizationFailureCount,metricNamespace=CloudTrailMetrics,metricValue=1
#
#   aws cloudwatch put-metric-alarm \
#     --region us-east-1 \
#     --alarm-name "Authorization Failures" \
#     --alarm-description "Alarm triggered when unauthorized API calls are made" \
#     --metric-name AuthorizationFailureCount \
#     --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_check31="3.1"
CHECK_TITLE_check31="[check31] Ensure a log metric filter and alarm exist for unauthorized API calls (Scored)"
CHECK_SCORED_check31="SCORED"
CHECK_TYPE_check31="LEVEL1"
CHECK_SEVERITY_check31="Medium"
CHECK_ASFF_TYPE_check31="Software and Configuration Checks/Industry and Regulatory Standards/CIS AWS Foundations Benchmark"
CHECK_ASFF_RESOURCE_TYPE_check31="AwsCloudTrailTrail"
CHECK_ALTERNATE_check301="check31"
CHECK_ASFF_COMPLIANCE_TYPE_check31="ens-op.exp.8.aws.trail.2"
CHECK_SERVICENAME_check31="iam"
CHECK_RISK_check31='Monitoring unauthorized API calls will help reveal application errors and may reduce time to detect malicious activity.'
CHECK_REMEDIATION_check31='It is recommended that a metric filter and alarm be established for unauthorized requests.'
CHECK_DOC_check31='https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudwatch-alarms-for-cloudtrail.html'
CHECK_CAF_EPIC_check31='Logging and Monitoring'

check31(){
  check3x '\$\.errorCode\s*=\s*"\*UnauthorizedOperation".+\$\.errorCode\s*=\s*"AccessDenied\*"'
}