Detection: Windows Svchost.exe Parent Process Anomaly

Description

The following analytic detects an anomaly where an svchost.exe process is spawned by a parent process other than the standard services.exe. In a typical Windows environment, svchost.exe is a system process that hosts Windows service DLLs, and is expected to be a child of services.exe. A process deviation from this hierarchy may indicate suspicious behavior, such as malicious code attempting to masquerade as a legitimate system process or evade detection. It is essential to investigate the parent process and associated behavior for further signs of compromise or unauthorized activity.

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 != "services.exe" AND Processes.process_name = "svchost.exe" AND Processes.process != unknown AND Processes.parent_process_path != "C:\\ProgramData\\Microsoft\\Windows Defender\\Platform\\*\\MsMpEng.exe" AND Processes.parent_process_path != "C:\\Program Files\\Windows Defender\\MsMpEng.exe" by Processes.parent_process_name Processes.parent_process_path Processes.parent_process Processes.process_path Processes.process Processes.original_file_name Processes.dest Processes.user 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_svchost_exe_parent_process_anomaly_filter`

Data Source

Name	Platform	Sourcetype	Source
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

Windows Update or other Windows Installer processes may launch their own svchost.exe processes that are not directly spawned by services.exe in certain edge cases (e.g., during patches or updates).

Associated Analytic Story

• China-Nexus Threat Activity

• Earth Estries

• SnappyBee

Risk Based Analytics (RBA)

Risk Message:

An svchost.exe process was spawned by an unexpected parent process [$parent_process_name$] instead of services.exe on [$dest$].

References

• https://attack.mitre.org/techniques/T1036/009/

• https://www.trendmicro.com/en_nl/research/24/k/earth-estries.html

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: 1