VT Relationships File Contacts IP

// Copyright 2023 Google LLC. Licensed under Apache-2.0.

rule vt_relationships_file_contacts_ip {

  meta:
    author = "Google Cloud Security"
    description = "Alert on known Hash contacting known IP with VT Relationships"
    rule_id = "mr_d6011593-c864-40b2-b300-4275ed163f5d"
    rule_name = "VT Relationships File Contacts IP"
    type = "alert"
    tags = "vt"
    data_source = "microsoft defender atp"
    severity = "High"
    priority = "High"

  events:
    $network.metadata.event_type = "NETWORK_CONNECTION"
    $network.principal.process.file.sha256 = $file_hash
    $network.target.ip = $ip
    $network.principal.hostname = $hostname

    // 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 ip address it contacts
    $vt.graph.relations.entity_type = "IP_ADDRESS"
    $vt.graph.relations.relationship = "CONTACTS"
    $vt.graph.relations.entity.ip = $ip

  match:
    $hostname over 5m

  outcome:
    $risk_score = 85
    $event_count = count_distinct($network.metadata.id)
    // added to populate alert graph with additional context
    $principal_ip = array_distinct($network.principal.ip)
    $target_ip = array_distinct($network.target.ip)
    $principal_process_pid = array_distinct($network.principal.process.pid)
    $principal_process_command_line = array_distinct($network.principal.process.command_line)
    $principal_process_file_sha256 = array_distinct($network.principal.process.file.sha256)
    $principal_process_file_full_path = array_distinct($network.principal.process.file.full_path)
    $principal_process_product_specific_process_id = array_distinct($network.principal.process.product_specific_process_id)
    $principal_process_parent_process_product_specific_process_id = array_distinct($network.principal.process.parent_process.product_specific_process_id)
    $target_process_pid = array_distinct($network.target.process.pid)
    $target_process_command_line = array_distinct($network.target.process.command_line)
    $target_process_file_sha256 = array_distinct($network.target.process.file.sha256)
    $target_process_file_full_path = array_distinct($network.target.process.file.full_path)
    $target_process_product_specific_process_id = array_distinct($network.target.process.product_specific_process_id)
    $target_process_parent_process_product_specific_process_id = array_distinct($network.target.process.parent_process.product_specific_process_id)
    $principal_user_userid = array_distinct($network.principal.user.userid)
    $target_user_userid = array_distinct($network.target.user.userid)

  condition:
    $network and $vt
}