Azure AD Multiple Users Failing To Authenticate From Ip
Description
The following analytic identifies one source Ip failing to authenticate with 30 unique valid users within 5 minutes. This behavior could represent an adversary performing a Password Spraying attack against an Azure Active Directory tenant to obtain initial access or elevate privileges. Error Code 50126 represents an invalid password. This logic can be used for real time security monitoring as well as threat hunting exercises.
Azure AD tenants can be very different depending on the organization. Users should test this detection and customize the arbitrary threshold if needed.
- Type: Anomaly
-
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-07-12
- Author: Mauricio Velazco, Gowthamaraj Rajendran, Splunk
- ID: 94481a6a-8f59-4c86-957f-55a71e3612a6
Annotations
ATT&CK
Kill Chain Phase
- Weaponization
- Exploitation
NIST
- DE.AE
CIS20
- CIS 10
CVE
Search
1
2
3
4
5
6
`azuread` category=SignInLogs properties.status.errorCode=50126 properties.authenticationDetails{}.succeeded=false
| rename properties.* as *
| bucket span=5m _time
| stats dc(userPrincipalName) AS unique_accounts values(userPrincipalName) as userPrincipalName by _time, ipAddress
| where unique_accounts > 30
| `azure_ad_multiple_users_failing_to_authenticate_from_ip_filter`
Macros
The SPL above uses the following Macros:
azure_ad_multiple_users_failing_to_authenticate_from_ip_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
- properties.status.errorCode
- category
- properties.authenticationDetails
- properties.userPrincipalName
- properties.ipAddress
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
A source Ip failing to authenticate with multiple users is not a common for legitimate behavior.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
63.0 | 70 | 90 | Source Ip $ipAddress$ failed to authenticate with 30 users within 5 minutes. |
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/T1110/003/
- https://docs.microsoft.com/en-us/security/compass/incident-response-playbook-password-spray
- https://www.cisa.gov/uscert/ncas/alerts/aa21-008a
- https://docs.microsoft.com/azure/active-directory/reports-monitoring/reference-sign-ins-error-codes
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