:warning: THIS IS A EXPERIMENTAL DETECTION

This detection has been marked experimental by the Splunk Threat Research team. This means we have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.

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Description

The following analytic seeks to detect the creation of Windows Management Instrumentation (WMI) permanent event subscriptions, a technique often used by adversaries for persistence. Such a subscription allows for the execution of specified scripts or binaries in response to defined system events, potentially enabling malicious activities to persist unnoticed. The analytic uses Sysmon Event ID 5 data, specifically focusing on instances where consumers of these events are not the expected "NTEventLogEventConsumer." Although WMI event subscriptions can be used legitimately by administrators, unusual or unexpected subscription creation should be treated as suspicious. Analysts need to be cognizant of the potential for false positives in legitimate administrative activities and should understand WMI activity within the context of the monitored environment.

  • Type: TTP

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

  • Last Updated: 2018-10-23
  • Author: Rico Valdez, Splunk
  • ID: 71bfdb13-f200-4c6c-b2c9-a2e07adf437d

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1047 Windows Management Instrumentation Execution
Kill Chain Phase
  • Installation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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`wmi` EventCode=5861 Binding 
| rex field=Message "Consumer =\s+(?<consumer>[^;
|^$]+)" 
| search consumer!="NTEventLogEventConsumer=\"SCM Event Log Consumer\"" 
| stats count min(_time) as firstTime max(_time) as lastTime by ComputerName, consumer, Message 
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)` 
| rename ComputerName as dest 
| `wmi_permanent_event_subscription_filter`

Macros

The SPL above uses the following Macros:

:information_source: wmi_permanent_event_subscription_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
  • Message
  • consumer
  • ComputerName

How To Implement

To successfully implement this search, you must be ingesting the Windows WMI activity logs. This can be done by adding a stanza to inputs.conf on the system generating logs with a title of [WinEventLog://Microsoft-Windows-WMI-Activity/Operational].

Known False Positives

Although unlikely, administrators may use event subscriptions for legitimate purposes.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 tbd

: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

source | version: 1