Detection: Windows Masquerading Explorer As Child Process

Description

The following analytic identifies instances where explorer.exe is spawned by unusual parent processes such as cmd.exe, powershell.exe, or regsvr32.exe. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and parent process relationships. This activity is significant because explorer.exe is typically initiated by userinit.exe, and deviations from this norm can indicate code injection or process masquerading attempts by malware like Qakbot. If confirmed malicious, this behavior could allow attackers to execute arbitrary code, evade detection, and maintain persistence within the environment.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name IN("cmd.exe", "powershell.exe", "regsvr32.exe") AND Processes.process_name = "explorer.exe" AND Processes.process IN ("*\\explorer.exe") by Processes.parent_process Processes.parent_process_name Processes.process_name Processes.process_id Processes.process_guid Processes.process Processes.user Processes.dest Processes.parent_process_id 
3| `drop_dm_object_name("Processes")` 
4| `security_content_ctime(firstTime)` 
5|`security_content_ctime(lastTime)` 
6| `windows_masquerading_explorer_as_child_process_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'xmlwineventlog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

unknown

Associated Analytic Story

• Compromised Windows Host

• Qakbot

Risk Based Analytics (RBA)

References

• https://malpedia.caad.fkie.fraunhofer.de/details/win.qakbot

Detection Testing

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: GitHub | Version: 4