Azure AD Authentication Failed During MFA Challenge
Description
The following analytic identifies an authentication attempt event against an Azure AD tenant that fails during the Multi Factor Authentication challenge. Error Code 500121 represents a failed attempt to authenticate using a second factor. This behavior may represent an adversary trying to authenticate with compromised credentials for an account that has multi-factor authentication enabled.
- Type: TTP
-
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-07-14
- Author: Mauricio Velazco, Gowthamaraj Rajendran, Splunk
- ID: e62c9c2e-bf51-4719-906c-3074618fcc1c
Annotations
ATT&CK
ATT&CK
ID | Technique | Tactic |
---|---|---|
T1586 | Compromise Accounts | Resource Development |
T1586.003 | Cloud Accounts | Resource Development |
T1078 | Valid Accounts | Defense Evasion, Persistence, Privilege Escalation, Initial Access |
T1078.004 | Cloud Accounts | Defense Evasion, Persistence, Privilege Escalation, Initial Access |
T1621 | Multi-Factor Authentication Request Generation | Credential Access |
Kill Chain Phase
- Weaponization
- Exploitation
- Installation
- Delivery
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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`azuread` category=SignInLogs properties.status.errorCode=500121
| rename properties.* as *
| stats values(userPrincipalName) as userPrincipalName by _time, ipAddress, status.additionalDetails, appDisplayName, userAgent
| `azure_ad_authentication_failed_during_mfa_challenge_filter`
Macros
The SPL above uses the following Macros:
azure_ad_authentication_failed_during_mfa_challenge_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
- category
- properties.status.errorCode
- properties.userPrincipalName
- properties.ipAddress
- properties.status.additionalDetails
- properties.appDisplayName
- properties.userAgent
How To Implement
You must install the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase (https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Active Directory events into your Splunk environment through an EventHub. Specifically, this analytic leverages the SignInLogs log category.
Known False Positives
Legitimate users may miss to reply the MFA challenge within the time window or deny it by mistake.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
54.0 | 60 | 90 | User $userPrincipalName$ failed to pass MFA challenge |
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
- https://attack.mitre.org/techniques/T1621/
- https://attack.mitre.org/techniques/T1078/004/
- https://docs.microsoft.com/en-us/azure/active-directory/authentication/concept-mfa-howitworks
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
source | version: 1