Detection: Remote Process Instantiation via WinRM and PowerShell

Updated Date: 2024-07-23 ID: ba24cda8-4716-11ec-8009-3e22fbd008af Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the execution of powershell.exe with arguments used to start a process on a remote endpoint via the WinRM protocol, specifically targeting the Invoke-Command cmdlet. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions and process telemetry. This activity is significant as it may indicate lateral movement or remote code execution attempts by adversaries. If confirmed malicious, this could allow attackers to execute arbitrary code on remote systems, potentially leading to further compromise and lateral spread within the network.

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_powershell` (Processes.process="*Invoke-Command*" AND Processes.process="*-ComputerName*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)`
5| `security_content_ctime(lastTime)` 
6| `remote_process_instantiation_via_winrm_and_powershell_filter`

Data Source

Name Platform Sourcetype Source Supported App
CrowdStrike ProcessRollup2 N/A 'crowdstrike:events:sensor' 'crowdstrike' N/A

Macros Used

Name Value
process_powershell (Processes.process_name=pwsh.exe OR Processes.process_name=sqlps.exe OR Processes.process_name=sqltoolsps.exe OR Processes.process_name=powershell.exe OR Processes.process_name=powershell_ise.exe OR Processes.original_file_name=pwsh.dll OR Processes.original_file_name=PowerShell.EXE OR Processes.original_file_name=powershell_ise.EXE)
remote_process_instantiation_via_winrm_and_powershell_filter search *
remote_process_instantiation_via_winrm_and_powershell_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1021 Remote Services Lateral Movement
T1021.006 Windows Remote Management Lateral Movement
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
Wizard Spider
Chimera
FIN13
Threat Group-3390
Wizard Spider

Default Configuration

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

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

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

Administrators may leverage WinRM and Invoke-Command to start a process on remote systems for system administration or automation use cases. However, this activity is usually limited to a small set of hosts or users.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A process was started on a remote endpoint from $dest$ by abusing WinRM using PowerShell.exe 45 90 50
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog

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: 3