Splunk User Enumeration Attempt
On May 3rd, 2022, Splunk published a security advisory for username enumeration stemming from verbose login failure messages present on some REST endpoints. This detection will alert on attempted exploitation in patched versions of Splunk as well as actual exploitation in unpatched version of Splunk.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-04-29
- Author: Lou Stella, Splunk
- ID: 25625cb4-1c4d-4463-b0f9-7cb462699cde
Kill Chain Phase
- CIS 10
|CVE-2021-33845||The Splunk Enterprise REST API allows enumeration of usernames via the lockout error message. The potential vulnerability impacts Splunk Enterprise instances before 8.1.7 when configured to repress verbose login errors.||5.0|
1 2 3 4 5 `splunkd_failed_auths` | stats count(user) as auths by user, src | where auths>5 | stats values(user) as "Users", sum(auths) as TotalFailedAuths by src | `splunk_user_enumeration_attempt_filter`
The SPL above uses the following Macros:
splunk_user_enumeration_attempt_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
This detection does not require you to ingest any new data. The detection does require the ability to search the _audit index. This detection may assist in efforts to find password spraying or brute force authorization attempts in addition to someone enumerating usernames.
Known False Positives
Automation executing authentication attempts against your Splunk infrastructure with outdated credentials may cause false positives.
Associated Analytic Story
|40.0||50||80||$TotalFailedAuths$ failed authentication events to Splunk from $src$ detected.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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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