Okta MFA Exhaustion Hunt

SPLUNK detection rule by Michael Haag, Marissa Bower, Mauricio Velazco, Splunk · Apache-2.0

The following analytic detects patterns of successful and failed Okta MFA push attempts to identify potential MFA exhaustion attacks. It leverages Okta event logs, specifically focusing on push verification events, and uses statistical evaluations to determine suspicious activity. This activity is significant as it may indicate an attacker attempting to bypass MFA by overwhelming the user with push notifications. If confirmed malicious, this could lead to unauthorized access, compromising the security of the affected accounts and potentially the entire environment.

name: Okta MFA Exhaustion Hunt
id: 97e2fe57-3740-402c-988a-76b64ce04b8d
version: 9
creation_date: '2022-12-19'
modification_date: '2026-05-13'
author: Michael Haag, Marissa Bower, Mauricio Velazco, Splunk
status: production
type: Hunting
description: The following analytic detects patterns of successful and failed Okta MFA push attempts to identify potential MFA exhaustion attacks. It leverages Okta event logs, specifically focusing on push verification events, and uses statistical evaluations to determine suspicious activity. This activity is significant as it may indicate an attacker attempting to bypass MFA by overwhelming the user with push notifications. If confirmed malicious, this could lead to unauthorized access, compromising the security of the affected accounts and potentially the entire environment.
data_source:
    - Okta
search: |-
    `okta` eventType=system.push.send_factor_verify_push OR ((legacyEventType=core.user.factor.attempt_success) AND (debugContext.debugData.factor=OKTA_VERIFY_PUSH)) OR ((legacyEventType=core.user.factor.attempt_fail) AND (debugContext.debugData.factor=OKTA_VERIFY_PUSH))
      | stats count(eval(legacyEventType="core.user.factor.attempt_success"))  as successes count(eval(legacyEventType="core.user.factor.attempt_fail")) as failures count(eval(eventType="system.push.send_factor_verify_push")) as pushes
        BY user,_time
      | stats latest(_time) as lasttime earliest(_time) as firsttime sum(successes) as successes sum(failures) as failures sum(pushes) as pushes
        BY user
      | eval seconds=lasttime-firsttime
      | eval lasttime=strftime(lasttime, "%c")
      | search (pushes>1)
      | eval totalattempts=successes+failures
      | eval finding="Normal authentication pattern"
      | eval finding=if(failures==pushes AND pushes>1,"Authentication attempts not successful because multiple pushes denied",finding)
      | eval finding=if(totalattempts==0,"Multiple pushes sent and ignored",finding)
      | eval finding=if(successes>0 AND pushes>3,"Probably should investigate. Multiple pushes sent, eventual successful authentication!",finding)
      | `okta_mfa_exhaustion_hunt_filter`
how_to_implement: The analytic leverages Okta OktaIm2 logs to be ingested using the Splunk Add-on for Okta Identity Cloud (https://splunkbase.splunk.com/app/6553).
known_false_positives: False positives may be present. Tune Okta and tune the analytic to ensure proper fidelity. Modify risk score as needed. Drop to anomaly until tuning is complete.
references:
    - https://developer.okta.com/docs/reference/api/event-types/?q=user.acount.lock
    - https://sec.okta.com/everythingisyes
    - https://splunkbase.splunk.com/app/6553
analytic_story:
    - Okta Account Takeover
    - Okta MFA Exhaustion
    - Scattered Lapsus$ Hunters
asset_type: Okta Tenant
mitre_attack_id:
    - T1110
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: application
security_domain: access
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1621/okta_multiple_failed_mfa_pushes/okta_multiple_failed_mfa_pushes.log
          source: Okta
          sourcetype: OktaIM2:log
      test_type: unit

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