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Detection rules › YARA-L

Google Workspace User Ou Changed

Severity
high
Type
Alert
Author
Google Cloud Security
Source
github.com/chronicle/detection-rules

Identifies when a Google Workspace user account is moved between Organizational Units.

MITRE ATT&CK coverage

TacticTechniques
PersistenceT1098.003 Account Manipulation: Additional Cloud Roles

Event coverage

ProviderEventTitle
GoogleWorkspace-adminMOVE_USER_TO_ORG_UNITMove User to Org Unit

Rules detecting the same action

Other rules on this platform that filter on the same API call or operation.

Rule body yaral

/*
 * 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_user_ou_changed {

  meta:
    author = "Google Cloud Security"
    description = "Identifies when a Google Workspace user account is moved between Organizational Units."
    rule_id = "mr_e265b499-9a83-4e7d-acf8-ae7674e1c743"
    rule_name = "Google Workspace User Ou Changed"
    mitre_attack_tactic = "Persistence"
    mitre_attack_technique = "Account Manipulation: Additional Cloud Roles"
    mitre_attack_url = "https://attack.mitre.org/techniques/T1098/003/"
    mitre_attack_version = "v13.1"
    type = "Alert"
    data_source = "Workspace Activity"
    severity = "High"
    priority = "High"

  events:
    $ws.metadata.vendor_name = "Google Workspace"
    $ws.metadata.product_name = "admin"
    $ws.metadata.product_event_type = "MOVE_USER_TO_ORG_UNIT"
    $ws.security_result.category_details = "USER_SETTINGS"

  outcome:
    $risk_score = max(70)
    $mitre_attack_tactic = "Persistence"
    $mitre_attack_technique = "Account Manipulation: Additional Cloud Roles"
    $mitre_attack_technique_id = "T1098.003"
    $event_count = count_distinct($ws.metadata.id)
    $principal_ip = array_distinct($ws.principal.ip)
    $principal_country = array_distinct($ws.principal.ip_geo_artifact.location.country_or_region)
    $principal_state = array_distinct($ws.principal.ip_geo_artifact.location.state)
    $principal_user_emails = array_distinct($ws.principal.user.email_addresses)
    $target_user_emails = array_distinct($ws.target.user.email_addresses)
    $principal_user_id = $ws.principal.user.userid
    $old_org_unit_name = $ws.about.labels["org_unit_name"]
    $new_org_unit_name = $ws.target.user.attribute.labels["new_value"]

  condition:
    $ws
}

Detection logic

Fires when at least one $ws event.

Events

$ws

  • metadata.product_event_type = "MOVE_USER_TO_ORG_UNIT"
  • security_result.category_details = "USER_SETTINGS"

Outcome

Fields the detection emits on a match. $risk_score drives alerting; Chronicle surfaces the rest on the detection.

FieldExpression
risk_scoremax(70)
event_countcount_distinct($ws.metadata.id)
principal_iparray_distinct($ws.principal.ip)
principal_countryarray_distinct($ws.principal.ip_geo_artifact.location.country_or_region)
principal_statearray_distinct($ws.principal.ip_geo_artifact.location.state)
principal_user_emailsarray_distinct($ws.principal.user.email_addresses)
target_user_emailsarray_distinct($ws.target.user.email_addresses)
principal_user_id$ws.principal.user.userid
old_org_unit_name$ws.about.labels["org_unit_name"]
new_org_unit_name$ws.target.user.attribute.labels["new_value"]