6_21_log4j_exploit_attempts.yaral

/*
 * Copyright 2022 Google LLC
 *
 * 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.
 */
 
 rule log4j_exploit_attempts {
    meta:
        author = "Don Sailing (CYDERES)"
        update = "Olivier BARESCUT (Google)"
        description = "Detection of a log4j exploit attempts"
        severity = "Medium"

    events:
        $event.metadata.vendor_name = "Google Cloud Platform"
        $event.metadata.product_name = "http_load_balancer"
        ($event.metadata.event_type = "NETWORK_HTTP" or $event.metadata.event_type = "NETWORK_CONNECTION") 

        and
        (
            re.regex($event.target.url,
                `(?i)(\$|\%24)(\{|\%7b).*j.*n.*d.*i.*(\:|\%3a)`)
            or
            re.regex($event.network.http.user_agent,
                `(?i)(\$|\%24)(\{|\%7b).*j.*n.*d.*i.*(\:|\%3a)`)
            or
            re.regex($event.network.http.referral_url,
                `(?i)(\$|\%24)(\{|\%7b).*j.*n.*d.*i.* (\:|\%3a)`)
        )

    
    condition:
        $event
}