Possible PowerShell Obfuscation Via Alias Cmdlets (via ps_script)

title: Possible PowerShell Obfuscation Via Alias Cmdlets (via ps_script)
id: 4c480da5-4d90-5e3c-9239-19abdc9c787c
status: stable
description: This rule detects Set-Alias or New-Alias cmdlet usage. That can be use as a mean to obfuscate PowerShell scripts
references:
    - https://attack.mitre.org/techniques/T1059/001/
    - https://attack.mitre.org/techniques/T1027/
    - https://github.com/1337Rin/Swag-PSO
author: Huntrule Team
date: 2026-01-08
tags:
    - attack.execution
    - attack.stealth
    - attack.t1027
    - attack.t1059.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains:
            - 'Set-Alias '
            - 'New-Alias '
    filter_main_cim:
        ScriptBlockText:
            - 'Set-Alias -Name ncms -Value New-CimSession -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name gcls -Value Get-CimClass -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name ncso -Value New-CimSessionOption -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name gcms -Value Get-CimSession -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name rcms -Value Remove-cimSession -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name rcie -Value Register-CimIndicationEvent -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name gcai -Value Get-CimAssociatedInstance -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name gcim -Value Get-CimInstance -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name scim -Value Set-CimInstance -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name ncim -Value New-CimInstance -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name rcim -Value Remove-cimInstance -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
            - 'Set-Alias -Name icim -Value Invoke-CimMethod -Option ReadOnly, AllScope -ErrorAction SilentlyContinue'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: low