Detectionmediumtest

Potentially Suspicious Powershell Script Execution From Temp Folder

Detects a potentially suspicious powershell script executions from temporary folder

Convert In Phoenix Studio

Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Florian Roth (Nextron Systems), Max Altgelt (Nextron Systems), Tim SheltonCreated Wed Jul 14Updated Tue Feb 17a6a39bdb-935c-4f0a-ab77-35f4bbf44d33windows

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

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_*