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Description

The following analytic identifies multiple failed multi-factor authentication requests for a single user within an Okta tenant. Specifically, the analytic triggers when more than 10 MFA user prompts fail within 10 minutes. The reasons for these failure could be several, like the user not responding in time or receiving multiple duplicate MFA requests. Okta tenants can be very different depending on the organization, Security teams should test this detection and customize these arbitrary thresholds. The detected behavior may represent an adversary who has obtained legitimate credentials for a user and continuously repeats login attempts in order to bombard users with MFA push notifications, SMS messages, and phone calls potentially resulting in the user finally accepting the authentication request. Threat actors like the Lapsus team and APT29 have leveraged this technique to bypass multi-factor authentication controls as reported by Mandiant and others.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-03-05
  • Author: Mauricio Velazco, Splunk
  • ID: 826dbaae-a1e6-4c8c-b384-d16898956e73

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1621 Multi-Factor Authentication Request Generation Credential Access
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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 `okta` eventType=user.authentication.auth_via_mfa outcome.result=FAILURE debugContext.debugData.factor!=PASSWORD_AS_FACTOR 
| bucket _time span=5m 
| stats count min(_time) as firstTime max(_time) as lastTime values(displayMessage) values(src_ip) as src_ip values(debugContext.debugData.factor) by _time src_user 
| where count >= 5 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `okta_multiple_failed_mfa_requests_for_user_filter`

Macros

The SPL above uses the following Macros:

:information_source: okta_multiple_failed_mfa_requests_for_user_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • eventType
  • outcome.result
  • debugContext.debugData.factor
  • displayMessage
  • src_user
  • src_ip

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

Multiple Failed MFA requests may also be a sign of authentication or application issues. Filter as needed and monitor for any unusual activity.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
42.0 60 70 Multiple failed MFA requests for user [$src_user$] from IP Address - [$src_ip$]. Investigate further to determine if this was authorized.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

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