: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 detects the creation of WMI temporary event subscriptions. WMI (Windows Management Instrumentation) is a management technology that allows administrators to perform various tasks on Windows-based systems. Temporary event subscriptions are created to monitor specific events or changes on a system that help to detect potential threats early and take proactive measures to protect the organization's systems and data. The detection is made by using the Splunk query wmi EventCode=5860 Temporary to search for events with EventCode 5860, which indicates the creation of a temporary WMI event subscription. To further refine the search results, the query uses regular expressions (rex) to extract the query used in the event subscription. Then, it filters known benign queries related to system processes such as 'wsmprovhost.exe' and 'AntiVirusProduct', 'FirewallProduct', 'AntiSpywareProduct', which helps to focus on potentially malicious or suspicious queries. The detection is important because it indicates malicious activity since attackers use WMI to run commands, gather information, or maintain persistence within a compromised system. False positives might occur since legitimate uses of WMI event subscriptions in the environment might trigger benign activities to be flagged. Therefore, an extensive triage is necessary to review the specific query and assess its intent. Additionally, capturing and inspecting relevant on-disk artifacts and analyzing concurrent processes can help to identify the source of the attack. Detecting the creation of these event subscriptions to identify potential threats early and take appropriate actions to mitigate the risks.

  • Type: TTP

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

  • Last Updated: 2018-10-23
  • Author: Rico Valdez, Splunk
  • ID: 38cbd42c-1098-41bb-99cf-9d6d2b296d83

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=5860 Temporary 
| rex field=Message "NotificationQuery =\s+(?<query>[^;
|^$]+)" 
| search query!="SELECT * FROM Win32_ProcessStartTrace WHERE ProcessName = 'wsmprovhost.exe'" AND query!="SELECT * FROM __InstanceOperationEvent WHERE TargetInstance ISA 'AntiVirusProduct' OR TargetInstance ISA 'FirewallProduct' OR TargetInstance ISA 'AntiSpywareProduct'" 
| stats count min(_time) as firstTime max(_time) as lastTime by ComputerName, query  
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)` 
| `wmi_temporary_event_subscription_filter`

Macros

The SPL above uses the following Macros:

:information_source: wmi_temporary_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
  • query

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

Some software may create WMI temporary event subscriptions for various purposes. The included search contains an exception for two of these that occur by default on Windows 10 systems. You may need to modify the search to create exceptions for other legitimate events.

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

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