#!/usr/bin/env bash

# Prowler - the handy cloud security tool (copyright 2018) 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_extra798="7.98"
CHECK_TITLE_extra798="[extra798] Check if Lambda functions have resource-based policy set as Public"
CHECK_SCORED_extra798="NOT_SCORED"
CHECK_CIS_LEVEL_extra798="EXTRA"
CHECK_SEVERITY_extra798="Critical"
CHECK_ASFF_RESOURCE_TYPE_extra798="AwsLambdaFunction"
CHECK_ALTERNATE_check798="extra798"
CHECK_SERVICENAME_extra798="lambda"
CHECK_RISK_extra798='Publicly accessible services could expose sensitive data to bad actors.'
CHECK_REMEDIATION_extra798='Grant usage permission on a per-resource basis and applying least privilege principle.'
CHECK_DOC_extra798='https://docs.aws.amazon.com/lambda/latest/dg/access-control-resource-based.html'
CHECK_CAF_EPIC_extra798='Infrastructure Security'

extra798(){
  for regx in $REGIONS; do
    LIST_OF_FUNCTIONS=$($AWSCLI lambda list-functions $PROFILE_OPT --region $regx --output text --query 'Functions[*].FunctionName' 2>&1)
    if [[ $(echo "$LIST_OF_FUNCTIONS" | grep -E 'AccessDenied|UnauthorizedOperation|AuthorizationError') ]]; then
        textInfo "$regx: Access Denied trying to list functions" "$regx"
        continue
    fi
    if [[ $LIST_OF_FUNCTIONS ]]; then
      for lambdafunction in $LIST_OF_FUNCTIONS; do
        # get the policy per function
        FUNCTION_POLICY=$($AWSCLI lambda get-policy  $PROFILE_OPT --region $regx --function-name $lambdafunction --query Policy --output text 2>/dev/null)
        if [[ $FUNCTION_POLICY ]]; then
          FUNCTION_POLICY_ALLOW_ALL=$(echo $FUNCTION_POLICY \
            | jq '.Statement[] | select(.Effect=="Allow") | select(.Principal=="*" or .Principal.AWS=="*" or .Principal.CanonicalUser=="*")')
          if [[ $FUNCTION_POLICY_ALLOW_ALL ]]; then
            textFail "$regx: Lambda function $lambdafunction has a policy with public access" "$regx" "$lambdafunction"
          else
            textPass "$regx: Lambda function $lambdafunction has a policy resource-based policy and is not public" "$regx" "$lambdafunction"
          fi
        else
          textPass "$regx: Lambda function $lambdafunction does not have resource-based policy" "$regx" "$lambdafunction"
        fi
      done
    else
      textInfo "$regx: No Lambda functions found" "$regx"
    fi
  done
}