Detection rules › Splunk

Remote Process Instantiation via WinRM and PowerShell

Status
production
Severity
medium
Group by
IntegrityLevel, command_line, computer_name, event_action, original_file_name, parent_command_line, parent_process_guid, parent_process_id, parent_process_name, process_guid, process_hash, process_id, process_name, user, user_id, vendor_product
Author
Mauricio Velazco, Splunk
Source
github.com/splunk/security_content

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.

MITRE ATT&CK coverage

Event coverage

Rule body splunk

name: Remote Process Instantiation via WinRM and PowerShell
id: ba24cda8-4716-11ec-8009-3e22fbd008af
version: 12
creation_date: '2021-11-15'
modification_date: '2026-05-13'
author: Mauricio Velazco, Splunk
status: production
type: TTP
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.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | 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.action Processes.dest Processes.original_file_name
         Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
         Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
         Processes.process Processes.process_exec Processes.process_guid
         Processes.process_hash Processes.process_id Processes.process_integrity_level
         Processes.process_name Processes.process_path Processes.user
         Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `remote_process_instantiation_via_winrm_and_powershell_filter`
how_to_implement: 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.
references:
    - https://attack.mitre.org/techniques/T1021/006/
    - https://pentestlab.blog/2018/05/15/lateral-movement-winrm/
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: A process was started on a remote endpoint from $dest$ by abusing WinRM using PowerShell.exe
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - Active Directory Lateral Movement
asset_type: Endpoint
mitre_attack_id:
    - T1021.006
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1021.006/lateral_movement_psh/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

Stages and Predicates

Stage 1: tstats

| 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.action Processes.dest Processes.original_file_name
     Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
     Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
     Processes.process Processes.process_exec Processes.process_guid
     Processes.process_hash Processes.process_id Processes.process_integrity_level
     Processes.process_name Processes.process_path Processes.user
     Processes.user_id Processes.vendor_product

Stage 2: search

| `drop_dm_object_name(Processes)`

Stage 3: search

| `security_content_ctime(firstTime)`

Stage 4: search

| `security_content_ctime(lastTime)`

Stage 5: search

| `remote_process_instantiation_via_winrm_and_powershell_filter`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Processes.original_file_nameeq
  • "PowerShell.EXE" corpus 120 (sigma 84, splunk 30, elastic 6)
  • "powershell_ise.EXE" corpus 51 (splunk 30, sigma 18, elastic 3)
  • "pwsh.dll" corpus 112 (sigma 79, splunk 30, elastic 3)
Processes.processeq
  • "*-ComputerName*"
  • "*Invoke-Command*" corpus 3 (sigma 2, splunk 1)
Processes.process_nameeq
  • "powershell.exe" corpus 104 (elastic 60, splunk 44)
  • "powershell_ise.exe" corpus 50 (splunk 29, elastic 21)
  • "pwsh.exe" corpus 62 (elastic 33, splunk 29)