Try in Splunk Security Cloud

Description

Windows Active Directory contains numerous objects. A statistically significant increase in access to these objects may be evidence of attacker enumeration of Active Directory.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2023-06-01
  • Author: Steven Dick
  • ID: 71b289db-5f2c-4c43-8256-8bf26ae7324a

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1087 Account Discovery Discovery
T1087.002 Domain Account Discovery
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`wineventlog_security` EventCode=4662 
| stats min(_time) AS firstTime, max(_time) AS lastTime, dc(ObjectName) AS ObjectName_count, values(ObjectType) AS ObjectType, latest(Computer) AS dest count BY SubjectUserName 
| eventstats avg(ObjectName_count) AS average stdev(ObjectName_count) AS standarddev 
| eval limit = round((average+(standarddev*3)),0), user = SubjectUserName 
| where ObjectName_count > limit 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)`
| `windows_ad_abnormal_object_access_activity_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_ad_abnormal_object_access_activity_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
  • EventCode
  • ObjectName
  • EventCode
  • SubjectUserName

How To Implement

Enable Audit Directory Service Access via GPO and collect event code 4662. The required SACLs need to be created for the relevant objects. Be aware Splunk filters this event by default on the Windows TA. Recommend pre-filtering any known service accounts that frequently query AD to make detection more accurate. Setting wide search window of 48~72hr may smooth out misfires.

Known False Positives

Service accounts or applications that routinely query Active Directory for information.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 The account $user$ accessed an abnormal amount ($ObjectName_count$) of [$ObjectType$] AD object(s) between $firstTime$ and $lastTime$.

:information_source: 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

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