prowler/checks/check23

#!/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.

CHECK_ID_check23="2.3"
CHECK_TITLE_check23="[check23] Ensure the S3 bucket CloudTrail logs to is not publicly accessible"
CHECK_SCORED_check23="SCORED"
CHECK_CIS_LEVEL_check23="LEVEL1"
CHECK_SEVERITY_check23="Critical"
CHECK_ASFF_TYPE_check23="Software and Configuration Checks/Industry and Regulatory Standards/CIS AWS Foundations Benchmark"
CHECK_ASFF_RESOURCE_TYPE_check23="AwsS3Bucket"
CHECK_ALTERNATE_check203="check23"
CHECK_ASFF_COMPLIANCE_TYPE_check23="ens-op.exp.10.aws.trail.3 ens-op.exp.10.aws.trail.4"
CHECK_SERVICENAME_check23="cloudtrail"
CHECK_RISK_check23='Allowing public access to CloudTrail log content may aid an adversary in identifying weaknesses in the affected accounts use or configuration.'
CHECK_REMEDIATION_check23='Analyze Bucket policy to validate appropriate permissions. Ensure the AllUsers principal is not granted privileges. Ensure the AuthenticatedUsers principal is not granted privileges.'
CHECK_DOC_check23='https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_principal.html'
CHECK_CAF_EPIC_check23='Logging and Monitoring'

check23(){
  trail_count=0
  # "Ensure the S3 bucket CloudTrail logs to is not publicly accessible (Scored)"
  for regx in $REGIONS; do
    TRAILS_AND_REGIONS=$($AWSCLI cloudtrail describe-trails $PROFILE_OPT --region $regx --query 'trailList[*].{Name:TrailARN, HomeRegion:HomeRegion}' --output text 2>&1 | tr "	" ',')
    if [[ $(echo "$TRAILS_AND_REGIONS" | grep AccessDenied) ]]; then
      textInfo "$regx: Access Denied trying to describe trails" "$regx" "$trail"
      continue
    fi
    if [[ $TRAILS_AND_REGIONS ]]; then
      for reg_trail in $TRAILS_AND_REGIONS; do
        TRAIL_REGION=$(echo $reg_trail | cut -d',' -f1)
        if [ $TRAIL_REGION != $regx ]; then # Only report trails once in home region
          continue
        fi
        trail=$(echo $reg_trail | cut -d',' -f2)
        trail_count=$((trail_count + 1))

        CLOUDTRAILBUCKET=$($AWSCLI cloudtrail describe-trails $PROFILE_OPT --region $TRAIL_REGION --query 'trailList[*].[S3BucketName]' --output text --trail-name-list $trail)
        if [[ -z $CLOUDTRAILBUCKET ]]; then
          textFail "Trail $trail in $TRAIL_REGION does not publish to S3"
          continue
        fi

        CLOUDTRAIL_ACCOUNT_ID=$(echo $trail | awk -F: '{ print $5 }')
        if [ "$CLOUDTRAIL_ACCOUNT_ID" != "$ACCOUNT_NUM" ]; then
          textInfo "Trail $trail in $TRAIL_REGION S3 logging bucket $CLOUDTRAILBUCKET is not in current account"
          continue
        fi

        #
        # LOCATION - requests referencing buckets created after March 20, 2019
        # must be made to S3 endpoints in the same region as the bucket was
        # created.
        #
        BUCKET_LOCATION=$($AWSCLI s3api get-bucket-location $PROFILE_OPT --region $regx --bucket $CLOUDTRAILBUCKET --output text 2>&1)
        if [[ $(echo "$BUCKET_LOCATION" | grep AccessDenied) ]]; then
          textInfo "Trail $trail in $TRAIL_REGION Access Denied getting bucket location for $CLOUDTRAILBUCKET"
          continue
        fi
        if [[ $BUCKET_LOCATION == "None" ]]; then
          BUCKET_LOCATION="us-east-1"
        fi
        if [[ $BUCKET_LOCATION == "EU" ]]; then
          BUCKET_LOCATION="eu-west-1"
        fi

        CLOUDTRAILBUCKET_HASALLPERMISIONS=$($AWSCLI s3api get-bucket-acl --bucket $CLOUDTRAILBUCKET $PROFILE_OPT --region $BUCKET_LOCATION --query 'Grants[?Grantee.URI==`http://acs.amazonaws.com/groups/global/AllUsers`]' --output text 2>&1)
        if [[ $(echo "$CLOUDTRAILBUCKET_HASALLPERMISIONS" | grep AccessDenied) ]]; then
          textInfo "Trail $trail in $TRAIL_REGION Access Denied getting bucket acl for $CLOUDTRAILBUCKET"
          continue
        fi

        if [[ -z $CLOUDTRAILBUCKET_HASALLPERMISIONS ]]; then
          textPass "Trail $trail in $TRAIL_REGION S3 logging bucket $CLOUDTRAILBUCKET is not publicly accessible"
        else
          textFail "Trail $trail in $TRAIL_REGION S3 logging bucket $CLOUDTRAILBUCKET is publicly accessible"
        fi

      done
    fi
  done
  if [[ $trail_count == 0 ]]; then
    textFail "$REGION: No CloudTrail trails were found in the account" "$REGION" "$trail"
  fi
}