Windows Enable PowerShell Web Access

SPLUNK detection rule by Michael Haag, Splunk · Apache-2.0

The following analytic detects the enabling of PowerShell Web Access via PowerShell commands. It leverages PowerShell script block logging (EventCode 4104) to identify the execution of the `Install-WindowsFeature` cmdlet with the `WindowsPowerShellWebAccess` parameter. 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.

name: Windows Enable PowerShell Web Access
id: 175bb2de-6227-416b-9678-9b61999cd21f
version: 11
creation_date: '2024-09-03'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic detects the enabling of PowerShell Web Access via PowerShell commands. It leverages PowerShell script block logging (EventCode 4104) to identify the execution of the `Install-WindowsFeature` cmdlet with the `WindowsPowerShellWebAccess` parameter. 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.
data_source:
    - Powershell Script Block Logging 4104
search: |-
    `powershell` EventCode=4104 ScriptBlockText IN ("*Install-WindowsFeature*WindowsPowerShellWebAccess*","*Install-PswaWebApplication*","*Add-PswaAuthorizationRule*UserName *ComputerName *")
      | fillnull
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY dest signature signature_id
           user_id vendor_product EventID
           Guid Opcode Name
           Path ProcessID ScriptBlockId
           ScriptBlockText
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `windows_enable_powershell_web_access_filter`
how_to_implement: To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://help.splunk.com/en/security-offerings/splunk-user-behavior-analytics/get-data-in/5.4.1/add-other-data-to-splunk-uba/configure-powershell-logging-to-see-powershell-anomalies-in-splunk-uba.
known_false_positives: It is possible that legitimate scripts or network administrators may enable PowerShell Web Access. Monitor and escalate as needed.
references:
    - https://www.cisa.gov/news-events/cybersecurity-advisories/aa24-241a
    - https://gist.github.com/MHaggis/7e67b659af9148fa593cf2402edebb41
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: PowerShell Web Access has been enabled on $dest$.
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - CISA AA24-241A
    - Malicious PowerShell
asset_type: Endpoint
mitre_attack_id:
    - T1059.001
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/T1059.001/powershell_script_block_logging/pswa_powershell.log
          sourcetype: XmlWinEventLog
          source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
      test_type: unit

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

4159be62-5095-439f-922e-4fb6f2fd5f40

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