Okta ThreatInsight Login Failure With High Unknown Users

/*
 * 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 okta_threatinsight_login_failure_with_high_unknown_users {

  meta:
    author = "Google Cloud Security"
    description = "Okta's ThreatInsight can identify multiple login failures with high unknown users count from the same IP across one or more Okta orgs."
    rule_id = "mr_41bafd12-7b1d-4b73-adf6-621c0431b538"
    rule_name = "Okta ThreatInsight Login Failure With High Unknown Users"
    reference = "https://help.okta.com/en-us/Content/Topics/Security/threat-insight/configure-threatinsight-system-log.htm"
    mitre_attack_tactic = "Credential Access"
    mitre_attack_technique = "Brute Force: Credential Stuffing"
    mitre_attack_url = "https://attack.mitre.org/techniques/T1110/004/"
    mitre_attack_version = "v13.1"
    type = "Alert"
    data_source = "Okta"
    severity = "Medium"
    priority = "Medium"

  events:
    $login.metadata.product_name = "Okta"
    $login.metadata.vendor_name = "Okta"
    $login.metadata.event_type = "USER_UNCATEGORIZED"
    $login.metadata.product_event_type = "security.threat.detected"
    $login.security_result.category_details = /Login failures with high unknown users count/
    $login.principal.user.userid = $userid
    $login.principal.ip = $ip

  match:
    $userid, $ip over 1h

  outcome:
    $risk_score = max(
        // Baseline
        35 +
        // If the IP Address is marked as suspicious IP address by Okta ThreatInsight
        if($login.security_result.detection_fields["threatSuspected"] = "true", 30) +
        // Unauthorized target geographies
        if($login.principal.ip_geo_artifact.location.country_or_region = "Cuba", 20) +
        if($login.principal.ip_geo_artifact.location.country_or_region = "Iran", 20) +
        if($login.principal.ip_geo_artifact.location.country_or_region = "North Korea", 20) +
        if($login.principal.ip_geo_artifact.location.country_or_region = "Russia", 20) +
        if($login.principal.ip_geo_artifact.location.country_or_region = "Syria", 20)
    )
    $mitre_attack_tactic = "Credential Access"
    $mitre_attack_technique = "Brute Force: Credential Stuffing"
    $target_user_agent = array_distinct($login.network.http.user_agent)
    $principal_ip = array_distinct($login.principal.ip)
    $principal_ip_country = array_distinct($login.principal.ip_geo_artifact.location.country_or_region)
    $principal_ip_state = array_distinct($login.principal.ip_geo_artifact.location.state)
    $principal_ip_city = array_distinct($login.principal.location.city)
    $security_result_summary = array_distinct($login.security_result.summary)

  condition:
    $login
}