Suspicious PowerShell Invocations - Specific - ProcessCreation (via process_creation)

title: Suspicious PowerShell Invocations - Specific - ProcessCreation (via process_creation)
id: d9383f4f-dcde-5fba-8ada-c31001648db0
status: stable
description: This rule detects anomalous PowerShell invocation command parameters
references:
    - Internal Research
author: Huntrule Team
date: 2026-06-11
tags:
    - attack.stealth
    - attack.execution
    - attack.defense-evasion
    - attack.t1059.001
    - attack.t1027
logsource:
    category: process_creation
    product: windows
detection:
    selection_convert_b64:
        CommandLine|contains|all:
            - '-nop'
            - ' -w '
            - 'hidden'
            - ' -c '
            - '[Convert]::FromBase64String'
    selection_iex:
        CommandLine|contains|all:
            - ' -w '
            - 'hidden'
            - '-noni'
            - '-nop'
            - ' -c '
            - 'iex'
            - 'New-Object'
    selection_enc:
        CommandLine|contains|all:
            - ' -w '
            - 'hidden'
            - '-ep'
            - 'bypass'
            - '-Enc'
    selection_reg:
        CommandLine|contains|all:
            - 'powershell'
            - 'reg'
            - 'add'
            - '\software\'
    selection_webclient:
        CommandLine|contains|all:
            - 'bypass'
            - '-noprofile'
            - '-windowstyle'
            - 'hidden'
            - 'new-object'
            - 'system.net.webclient'
            - '.download'
    selection_iex_webclient:
        CommandLine|contains|all:
            - 'iex'
            - 'New-Object'
            - 'Net.WebClient'
            - '.Download'
    filter_chocolatey:
        CommandLine|contains:
            - "(New-Object System.Net.WebClient).DownloadString('https://community.chocolatey.org/install.ps1"
            - 'Write-ChocolateyWarning'
    condition: 1 of selection_* and not 1 of filter_*
falsepositives:
    - Unknown
level: medium