This search detects when an excessive number of authentication failures occur this search also includes attempts against MFA prompt codes
- Type: Anomaly
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Authentication
- Last Updated: 2022-02-18
- Author: Rod Soto, Splunk
- ID: d441364c-349c-453b-b55f-12eccab67cf9
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 `o365_management_activity` Workload=AzureActiveDirectory UserAuthenticationMethod=* status=failure | stats count earliest(_time) AS firstTime latest(_time) AS lastTime values(UserAuthenticationMethod) AS UserAuthenticationMethod values(UserAgent) AS UserAgent values(status) AS status values(src_ip) AS src_ip by user | where count > 10 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `o365_excessive_authentication_failures_alert_filter`
The SPL above uses the following Macros:
o365_excessive_authentication_failures_alert_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
You must install splunk Microsoft Office 365 add-on. This search works with o365:management:activity
Known False Positives
The threshold for alert is above 10 attempts and this should reduce the number of false positives.
Associated Analytic Story
|64.0||80||80||User $user$ has caused excessive number of authentication failures from $src_ip$ using UserAgent $UserAgent$.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 2