Google Workspace Malicious File Downloaded

/*
 * Copyright 2023 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
 *
 *     https://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 google_workspace_malicious_file_downloaded {

  meta:
    author = "Google Cloud Security"
    description = "Identifies when a user downloads a potentially malicious file from Google Drive."
    rule_id = "mr_72af4504-955b-4c61-9071-bb767c9bae88"
    rule_name = "Google Workspace Malicious File Downloaded"
    mitre_attack_tactic = "Execution"
    mitre_attack_technique = "User Execution: Malicious File"
    mitre_attack_url = "https://attack.mitre.org/techniques/T1204/002/"
    mitre_attack_version = "v13.1"
    type = "Alert"
    data_source = "Workspace Activity"
    severity = "Medium"
    priority = "Medium"

  events:
    $ws.metadata.vendor_name = "Google Workspace"
    $ws.metadata.product_name = "drive"
    ($ws.metadata.product_event_type = "download" or
    $ws.metadata.product_event_type = "view" or
    $ws.metadata.product_event_type = "copy")

    ($ws.target.resource.attribute.labels["visibility"] = "people_with_link" or
    $ws.target.resource.attribute.labels["visibility"] = "public_on_the_web")
    $ws.target.resource.name = /.*\.dll|.*\.exe|.*\.scr|.*\.jar|.*\.pif|.*\.app|.*\.dmg|.*\.pkg|.*\.elf|.*\.so|.*\.bin|.*\.deb|.*\.rpm|.*\.sh|.*\.hta|.*\.lnk/

  outcome:
    $risk_score = max(35)
    $mitre_attack_tactic = "Execution"
    $mitre_attack_technique = "User Execution: Malicious File"
    $mitre_attack_technique_id = "T1204.002"
    $event_count = count_distinct($ws.metadata.id)
    $product_event_type = $ws.metadata.product_event_type
    $userid = $ws.principal.user.userid
    $doc_type = $ws.src.resource.attribute.labels["doc_type"]
    $owner = $ws.target.resource.attribute.labels["owner"]
    $doc_name = $ws.target.resource.name
    //$doc_id = $ws.target.resource.product_object_id

  condition:
    $ws
}