#!/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_extra7180="7.180"
CHECK_TITLE_extra7180="[extra7180] Check Lambda Function URL CORS configuration"
CHECK_SCORED_extra7180="NOT_SCORED"
CHECK_CIS_LEVEL_extra7180="EXTRA"
CHECK_SEVERITY_extra7180="Critical"
CHECK_ASFF_RESOURCE_TYPE_extra7180="AwsLambdaFunction"
CHECK_ALTERNATE_check7180="extra7180"
CHECK_SERVICENAME_extra7180="lambda"
CHECK_RISK_extra7180='Publicly accessible services could expose sensitive data to bad actors.'
CHECK_REMEDIATION_extra7180='Grant usage permission on a per-resource basis and applying least privilege principle.'
CHECK_DOC_extra7180='https://docs.aws.amazon.com/secretsmanager/latest/userguide/lambda-functions.html'
CHECK_CAF_EPIC_extra7180='Infrastructure Security'

extra7180(){
    for regx in ${REGIONS}; do
        LIST_OF_FUNCTIONS=$("${AWSCLI}" lambda list-functions ${PROFILE_OPT} \
            --region "${regx}" \
            --query 'Functions[*].FunctionName' \
            --output text 2>&1)
        # Check errors
        if grep -q -E 'AccessDenied|UnauthorizedOperation|AuthorizationError' <<< "${LIST_OF_FUNCTIONS}"; then
            textInfo "${regx}: Access Denied trying to list Lambda functions" "${regx}"
            continue
        fi
        if [[ -n "${LIST_OF_FUNCTIONS}" && $(tr '[:upper:]' '[:lower:]' <<< "${LIST_OF_FUNCTIONS}") != "none" ]]; then
            for lambda_function in ${LIST_OF_FUNCTIONS}; do
                # Check if Lambda function has an URL
                LAMBDA_FUNCTION_URL=$("${AWSCLI}" lambda list-function-url-configs ${PROFILE_OPT} \
                    --function-name "${lambda_function}" \
                    --region "${regx}" \
                    --query 'FunctionUrlConfigs[0].[FunctionUrl]' \
                    --output text)
                # Check errors
                if grep -q -E 'AccessDenied|UnauthorizedOperation|AuthorizationError' <<< "${AUTH_TYPE}"; then
                    textInfo "${regx}: Access Denied trying to get Lambda functions URLs" "${regx}"
                    continue
                fi

                if [[ "${LAMBDA_FUNCTION_URL}" != "None" ]]; then
                    # Check CORS configuration
                    CORS_ALLOW_ORIGINS=$("${AWSCLI}" lambda get-function-url-config ${PROFILE_OPT} \
                    --function-name "${lambda_function}" \
                    --region "${regx}" \
                    --query 'Cors.AllowOrigins' \
                    --output text)
                    # Check errors
                    if grep -q -E 'AccessDenied|UnauthorizedOperation|AuthorizationError' <<< "${AUTH_TYPE}"; then
                        textInfo "${regx}: Access Denied trying to get Lambda functions URLs configuration" "${regx}"
                        continue
                    fi

                    # The * is on purpose to check allowed origins
                    if [[ "${CORS_ALLOW_ORIGINS}" =~ "*" ]]; then
                        textFail "$regx: Lambda function ${lambda_function} URL has a wide CORS configuration" "${regx}" "${lambda_function}"
                    elif [[ "${CORS_ALLOW_ORIGINS}" == "None" ]]; then
                        textFail "${regx}: Lambda function ${lambda_function} URL has not CORS configured" "${regx}" "${lambda_function}"
                    else
                        textPass "${regx}: Lambda function ${lambda_function} has not a wide CORS configuration" "${regx}" "${lambda_function}"
                    fi

                else
                    textInfo "${regx}: Lambda function ${lambda_function} has not a function URL" "${regx}" "${lambda_function}"
                fi
            done
        else
            textInfo "${regx}: No Lambda functions found" "${regx}"
        fi
    done
}