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Description

The following analytic detects the installation of PowerShell Web Access using the Deployment Image Servicing and Management (DISM) tool. It leverages Sysmon Event ID 1 to identify the execution of dism.exe with specific parameters related to enabling the WindowsPowerShellWebAccess feature. This activity is significant because enabling PowerShell Web Access can facilitate remote execution of PowerShell commands, potentially allowing an attacker to gain unauthorized access to systems and networks. If confirmed malicious, this action could lead to further exploitation and compromise of the affected system.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint, Web
  • Last Updated: 2024-09-03
  • Author: Michael Haag, Splunk
  • ID: fa6142a7-c364-4d11-9954-895dd9efb2d4

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1548.002 Bypass User Account Control Privilege Escalation, Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


1
2
3
4
5
6



 
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=dism.exe (Processes.process="*WindowsPowerShellWebAccess*" AND Processes.process="*/online*" AND Processes.process="*/enable-feature*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_dism_install_powershell_web_access_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_dism_install_powershell_web_access_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
  • dest
  • user
  • parent_process_name
  • process_name
  • original_file_name
  • process
  • process_id
  • parent_process_id

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 using the DISM tool to update and install Windows features may cause false positives that can be filtered with windows_dism_install_powershell_web_access_filter.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
72.0 90 80 PowerShell Web Access has been installed on $dest$.

: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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