Potentially Suspicious Powershell Script Execution From Temp Folder

SIGMA detection rule by Florian Roth (Nextron Systems), Max Altgelt (Nextron Systems), Tim Shelton · NOASSERTION

Detects a potentially suspicious powershell script executions from temporary folder

title: Potentially Suspicious Powershell Script Execution From Temp Folder
id: a6a39bdb-935c-4f0a-ab77-35f4bbf44d33
status: test
description: Detects a potentially suspicious powershell script executions from temporary folder
references:
    - https://www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit/
author: Florian Roth (Nextron Systems), Max Altgelt (Nextron Systems), Tim Shelton
date: 2021-07-14
modified: 2026-02-17
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
        CommandLine|contains:
            - '\Windows\Temp'
            - '\Temporary Internet'
            - '\AppData\Local\Temp'
            - '\AppData\Roaming\Temp'
            - '%TEMP%'
            - '%TMP%'
            - '%LocalAppData%\Temp'
    filter_optional_vscode:
        CommandLine|contains: '-WindowStyle hidden -Verb runAs'
    filter_optional_amazon_ec2:
        CommandLine|contains: '\Windows\system32\config\systemprofile\AppData\Local\Temp\Amazon\EC2-Windows\'
    filter_optional_generic:
        CommandLine|contains:
            - ' >'
            - 'Out-File'
            - 'ConvertTo-Json'
    filter_optional_chocolatey_installer:
        ParentImage:
            - 'C:\Windows\System32\Msiexec.exe'
            - 'C:\Windows\SysWOW64\Msiexec.exe'
        Image|endswith: '\powershell.exe'
        CommandLine|contains|all:
            - '-NoProfile -ExecutionPolicy Bypass -Command'
            - 'AppData\Local\Temp\'
            - 'Install-Chocolatey.ps1'
    condition: selection and not 1 of filter_optional_*
falsepositives:
    - Administrative scripts
level: medium
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_powershell_script_exec_from_temp_folder/info.yml

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

18e760c2-663b-423b-a24b-740433bfca88

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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

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