Azure AD High Number Of Failed Authentications For User
Description
The following analytic identifies an Azure AD account with more than 20 failed authentication events in the span of 5 minutes. This behavior could represent a brute force attack against the account. As environments differ across organizations, security teams should customize the threshold of this detection.
- Type: TTP
-
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2023-01-23
- Author: Mauricio Velazco, Splunk
- ID: 630b1694-210a-48ee-a450-6f79e7679f2c
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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`azuread` category= SignInLogs properties.status.errorCode=50126 properties.authenticationDetails{}.succeeded=false
| rename properties.* as *
| bucket span=5m _time
| stats dc(_raw) AS failed_attempts values(ipAddress) by userPrincipalName, _time
| where failed_attempts > 20
| `azure_ad_high_number_of_failed_authentications_for_user_filter`
Macros
The SPL above uses the following Macros:
azure_ad_high_number_of_failed_authentications_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
- 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 user with more than 20 failed authentication attempts in the span of 5 minutes may also be triggered by a broken application.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
35.0 | 50 | 70 | User $userPrincipalName$ failed to authenticate more than 20 times in the span of 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
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