Kerberos User Enumeration

Name:Kerberos User Enumeration
id:d82d4af4-a0bd-11ec-9445-3e22fbd008af
version:11
date:2026-03-10
author:Mauricio Velazco, Splunk
status:production
type:Anomaly
Description:The following analytic detects an unusual number of Kerberos Ticket Granting Ticket (TGT) requests for non-existing users from a single source endpoint. It leverages Event ID 4768 and identifies anomalies using the 3-sigma statistical rule. This behavior is significant as it may indicate an adversary performing a user enumeration attack against Active Directory. If confirmed malicious, the attacker could validate a list of usernames, potentially leading to further attacks such as brute force or credential stuffing, compromising the security of the environment.
Data_source:

• -Windows Event Log Security 4768

search:`wineventlog_security` EventCode=4768 Status=0x6 TargetUserName!="*$"

| bucket span=2m _time

| stats dc(TargetUserName) AS unique_accounts values(TargetUserName) as tried_accounts values(dest) as dest
BY _time, src_ip

| eventstats avg(unique_accounts) as comp_avg , stdev(unique_accounts) as comp_std
BY src_ip

| eval upperBound=(comp_avg+comp_std*3)

| eval isOutlier=if(unique_accounts > 10 and unique_accounts >= upperBound, 1, 0)

| search isOutlier=1

| `kerberos_user_enumeration_filter`

how_to_implement:To successfully implement this search, you need to be ingesting Domain Controller and Kerberos events. The Advanced Security Audit policy setting `Audit Kerberos Authentication Service` within `Account Logon` needs to be enabled.
known_false_positives:Possible false positive scenarios include but are not limited to vulnerability scanners and missconfigured systems.
References:
  -https://github.com/ropnop/kerbrute
  -https://attack.mitre.org/techniques/T1589/002/
  -https://redsiege.com/tools-techniques/2020/04/user-enumeration-part-3-windows/
drilldown_searches:
 name:'View the detection results for - "$src_ip$"'
 search:'%original_detection_search% | search src_ip = "$src_ip$"'
 earliest_offset:'$info_min_time$'
 latest_offset:'$info_max_time$'
 name:'View risk events for the last 7 days for - "$src_ip$"'
 search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src_ip$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
 earliest_offset:'$info_min_time$'
 latest_offset:'$info_max_time$'
tags:
  analytic_story:
    - 'Active Directory Kerberos Attacks'
  asset_type:Endpoint
  mitre_attack_id:
    - 'T1589.002'
  product:
    - 'Splunk Enterprise'
    - 'Splunk Enterprise Security'
    - 'Splunk Cloud'
  security_domain:endpoint

tests:
 name:'True Positive Test'
 attack_data:
  data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1589.002/kerberos_user_enumeration/windows-xml.log
  source: XmlWinEventLog:Security
  sourcetype: XmlWinEventLog
manual_test:None