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vt_relationships_file_contacts_domain.yaral
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vt_relationships_file_contacts_domain.yaral
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/*
* 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 vt_relationships_file_contacts_domain {
meta:
author = "Google Cloud Security"
description = "Alert on known Hash querying a known hostname with VT Relationships"
type = "alert"
tags = "vt"
data_source = "microsoft sysmon, crowdstrike"
severity = "High"
priority = "High"
events:
$dns.metadata.event_type = "NETWORK_DNS"
$dns.principal.process.file.sha256 = $file_hash
$dns.network.dns.questions.name = $domain
strings.coalesce($dns.principal.hostname, $dns.target.user.userid) = $hostname_or_userid
// Uses VirusTotal integration via entity graph, this section maps to principal process file hash
$vt.graph.metadata.entity_type = "FILE"
$vt.graph.metadata.source_type = "GLOBAL_CONTEXT"
$vt.graph.metadata.vendor_name = "VirusTotal"
$vt.graph.metadata.product_name = "VirusTotal Relationships"
$vt.graph.entity.file.sha256 = $file_hash
// Uses VirusTotal integration via entity graph, this section maps the hash to the domain it contacts
$vt.graph.relations.entity_type = "DOMAIN_NAME"
$vt.graph.relations.relationship = "CONTACTS"
$vt.graph.relations.entity.domain.name = $domain
match:
$hostname_or_userid over 5m
outcome:
$risk_score = max(85)
$event_count = count_distinct($dns.metadata.id)
$network_dns_questions_name = array_distinct($dns.network.dns.questions.name)
$network_dns_answers_data = array_distinct($dns.network.dns.answers.data)
// added to populate alert graph with additional context
$principal_ip = array_distinct($dns.principal.ip)
$target_ip = array_distinct($dns.target.ip)
$principal_process_pid = array_distinct($dns.principal.process.pid)
$principal_process_file_full_path = array_distinct($dns.principal.process.file.full_path)
$principal_process_product_specific_process_id = array_distinct($dns.principal.process.product_specific_process_id)
$principal_user_userid = array_distinct($dns.principal.user.userid)
$principal_process_command_line = array_distinct($dns.principal.process.command_line)
$principal_process_file_sha256 = array_distinct($dns.principal.process.file.sha256)
$principal_process_parent_process_product_specific_process_id = array_distinct($dns.principal.process.parent_process.product_specific_process_id)
condition:
$dns and $vt
}