Potentially Suspicious Powershell Script Execution From Temp Folder

Hunt Hypothesis

Detects a potentially suspicious powershell script executions from temporary folder

Detection Rule

Sigma (Original)

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

KQL (Azure Sentinel)

imProcessCreate
| where ((TargetProcessName endswith "\\powershell.exe" or TargetProcessName endswith "\\pwsh.exe") and (TargetProcessCommandLine contains "\\Windows\\Temp" or TargetProcessCommandLine contains "\\Temporary Internet" or TargetProcessCommandLine contains "\\AppData\\Local\\Temp" or TargetProcessCommandLine contains "\\AppData\\Roaming\\Temp" or TargetProcessCommandLine contains "%TEMP%" or TargetProcessCommandLine contains "%TMP%" or TargetProcessCommandLine contains "%LocalAppData%\\Temp")) and (not((TargetProcessCommandLine contains "-WindowStyle hidden -Verb runAs" or TargetProcessCommandLine contains "\\Windows\\system32\\config\\systemprofile\\AppData\\Local\\Temp\\Amazon\\EC2-Windows\\" or (TargetProcessCommandLine contains " >" or TargetProcessCommandLine contains "Out-File" or TargetProcessCommandLine contains "ConvertTo-Json") or (((ParentProcessName in~ ("C:\\Windows\\System32\\Msiexec.exe", "C:\\Windows\\SysWOW64\\Msiexec.exe")) or (ActingProcessName in~ ("C:\\Windows\\System32\\Msiexec.exe", "C:\\Windows\\SysWOW64\\Msiexec.exe"))) and TargetProcessName endswith "\\powershell.exe" and (TargetProcessCommandLine contains "-NoProfile -ExecutionPolicy Bypass -Command" and TargetProcessCommandLine contains "AppData\\Local\\Temp\\" and TargetProcessCommandLine contains "Install-Chocolatey.ps1")))))

Required Data Sources

False Positive Guidance

• Administrative scripts

MITRE ATT&CK Context

• Tactic: Execution
• Technique: T1059.001 — PowerShell

References

• https://www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit/
• SigmaHQ Rule