#!/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/>.

check3x(){
  grep_filter=$1
  local CHECK_OK
  local CHECK_WARN
  local CHECK_CROSS_ACCOUNT_WARN

  CLOUDWATCH_GROUP=$($AWSCLI cloudtrail describe-trails $PROFILE_OPT --region "$REGION" --query 'trailList[*].CloudWatchLogsLogGroupArn' --output text| tr '\011' '\012' | awk -F: '{print $7}')
  CURRENT_ACCOUNT_ID=$($AWSCLI sts $PROFILE_OPT get-caller-identity --region "$REGION" --query Account --output text)

  if [[ $CLOUDWATCH_GROUP ]];then
    for group in $CLOUDWATCH_GROUP; do
      CLOUDWATCH_LOGGROUP_REGION=$($AWSCLI cloudtrail describe-trails $PROFILE_OPT --region "$REGION" --query 'trailList[*].CloudWatchLogsLogGroupArn' --output text | tr '\011' '\012' | grep "$group" | awk -F: '{ print $4 }'  | head -n 1)
      CLOUDWATCH_ACCOUNT_ID=$($AWSCLI cloudtrail describe-trails $PROFILE_OPT --region "$REGION" --query 'trailList[*].CloudWatchLogsLogGroupArn' --output text | tr '\011' '\012' | grep "$group" | awk -F: '{ print $5 }'  | head -n 1)
      if [ "$CLOUDWATCH_ACCOUNT_ID" == "$CURRENT_ACCOUNT_ID" ];then
        METRICFILTER_SET=$($AWSCLI logs describe-metric-filters --log-group-name "$group" $PROFILE_OPT --region "$CLOUDWATCH_LOGGROUP_REGION" --output text | grep METRICFILTERS | grep -E "$grep_filter" | awk '{ print $3 }')
      fi
      if [[ $METRICFILTER_SET ]];then
        for metric in $METRICFILTER_SET; do
          metric_name=$($AWSCLI logs describe-metric-filters $PROFILE_OPT --region "$CLOUDWATCH_LOGGROUP_REGION" --log-group-name "$group" --filter-name-prefix "$metric" --output text --query 'metricFilters[0].metricTransformations[0].metricName')
          HAS_ALARM_ASSOCIATED=$($AWSCLI cloudwatch describe-alarms $PROFILE_OPT --region "$CLOUDWATCH_LOGGROUP_REGION" --query 'MetricAlarms[?MetricName==`'"$metric_name"'`]' --output text)
          if [[ $HAS_ALARM_ASSOCIATED ]];then
            CHECK_OK="$CHECK_OK $group:$metric"
          else
            CHECK_WARN="$CHECK_WARN $group:$metric"
          fi
        done
      elif [ "$CLOUDWATCH_ACCOUNT_ID" == "$CURRENT_ACCOUNT_ID" ];then
        CHECK_WARN="$CHECK_WARN $group"
      else
        CHECK_CROSS_ACCOUNT_WARN="$CHECK_CROSS_ACCOUNT_WARN $group"
      fi
    done

    if [[ $CHECK_OK ]]; then
      for group in $CHECK_OK; do
        metric=${group#*:}
        group=${group%:*}
        textPass "CloudWatch group $group found with metric filter $metric and alarms set"
      done
    fi
    if [[ $CHECK_WARN ]]; then
      for group in $CHECK_WARN; do
        case $group in
           *:*) metric=${group#*:}
                group=${group%:*}
                textFail "CloudWatch group $group found with metric filter $metric but no alarms associated"
                ;;
             *) textFail "CloudWatch group $group found but no metric filters or alarms associated"
        esac
      done
    fi
    if [[ $CHECK_CROSS_ACCOUNT_WARN ]]; then
      for group in $CHECK_CROSS_ACCOUNT_WARN; do
        textInfo "CloudWatch group $group is not in this account"
      done
    fi
  else
    textFail "No CloudWatch group found for CloudTrail events"
  fi
}