prowler/checks/check_extra778

#!/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_extra778="7.78"
CHECK_TITLE_extra778="[extra778] Find VPC security groups with wide-open public IPv4 CIDR ranges (non-RFC1918) "
CHECK_SCORED_extra778="NOT_SCORED"
CHECK_CIS_LEVEL_extra778="EXTRA"
CHECK_SEVERITY_extra778="Medium"
CHECK_ASFF_RESOURCE_TYPE_extra778="AwsEc2SecurityGroup"
CHECK_ALTERNATE_check778="extra778"
CHECK_SERVICENAME_extra778="ec2"
CHECK_RISK_extra778='If Security groups are not properly configured the attack surface is increased. '
CHECK_REMEDIATION_extra778='Use a Zero Trust approach. Narrow ingress traffic as much as possible. Consider north-south as well as east-west traffic.'
CHECK_DOC_extra778='https://docs.aws.amazon.com/vpc/latest/userguide/VPC_SecurityGroups.html'
CHECK_CAF_EPIC_extra778='Infrastructure Security'

extra778(){
    CIDR_THRESHOLD=24
    RFC1918_REGEX="(^127\.)|(^10\.)|(^172\.1[6-9]\.)|(^172\.2[0-9]\.)|(^172\.3[0-1]\.)|(^192\.168\.)"

    check_cidr() {
        local SECURITY_GROUP=$1
        local DIRECTION=$2
        local DIRECTION_FILTER=""
        local REGION=$3

        case ${DIRECTION} in
            "inbound")
                DIRECTION_FILTER="IpPermissions"
                ;;
            "outbound")
                DIRECTION_FILTER="IpPermissionsEgress"
                ;;
        esac

        CIDR_IP_LIST=$(${AWSCLI} ec2 describe-security-groups \
                        ${PROFILE_OPT} \
                        --filter "Name=group-id,Values=${SECURITY_GROUP}" \
                        --query "SecurityGroups[*].${DIRECTION_FILTER}[*].IpRanges[*].CidrIp" \
                        --region ${REGION} \
                        --output text 2>&1| xargs )
        if [[ $(echo "$CIDR_IP_LIST" | grep -E 'AccessDenied|UnauthorizedOperation|AuthorizationError') ]]; then
            textInfo "$regx: Access Denied trying to describe security groups" "$regx"
            continue
        fi

        for CIDR_IP in ${CIDR_IP_LIST}; do
            if [[ ! ${CIDR_IP} =~ ${RFC1918_REGEX} ]]; then
                CIDR=$(echo ${CIDR_IP} | cut -d"/" -f2 | xargs)

                # Edge case "0.0.0.0/0" for RDP and SSH are checked already by check41 and check42
                if [[ ${CIDR} < ${CIDR_THRESHOLD} && 0 < ${CIDR} ]]; then
                    textFail "${REGION}: ${SECURITY_GROUP} has potential wide-open non-RFC1918 address ${CIDR_IP} in ${DIRECTION} rule" "${REGION}" "${SECURITY_GROUP}"
                else
                    textPass "${REGION}: ${SECURITY_GROUP} has no potential wide-open non-RFC1918 address" "${REGION}" "${SECURITY_GROUP}"
                fi
            fi
        done
    }

    for regx in ${REGIONS}; do
        SECURITY_GROUP_IDS=$(${AWSCLI} ec2 describe-security-groups \
                              ${PROFILE_OPT} \
                              --region ${regx} \
                              --query 'SecurityGroups[*].GroupId' \
                              --output text 2>&1| xargs )
        if [[ $(echo "$SECURITY_GROUP_IDS" | grep -E 'AccessDenied|UnauthorizedOperation|AuthorizationError') ]]; then
            textInfo "$regx: Access Denied trying to describe security groups" "$regx"
            continue
        fi
        for SECURITY_GROUP in ${SECURITY_GROUP_IDS}; do
            check_cidr "${SECURITY_GROUP}" "inbound" "${regx}"
            check_cidr "${SECURITY_GROUP}" "outbound" "${regx}"
        done
    done
}