Potential PowerShell Execution Via DLL — Sigma Rule

Rule metadata and linked tags

Author: Markus Neis, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2018-08-25 / 2024-03-07.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 9488799add24f4310f5bf4b72c4479216ad343a0fec79fa0e61ed71545da04f2

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Potential PowerShell Execution Via DLL
id: 6812a10b-60ea-420c-832f-dfcc33b646ba
status: test
description: |
    Detects potential PowerShell execution from a DLL instead of the usual PowerShell process as seen used in PowerShdll.
    This detection assumes that PowerShell commands are passed via the CommandLine.
references:
    - https://github.com/p3nt4/PowerShdll/blob/62cfa172fb4e1f7f4ac00ca942685baeb88ff356/README.md
author: Markus Neis, Nasreddine Bencherchali (Nextron Systems)
date: 2018-08-25
modified: 2024-03-07
tags:
    - attack.stealth
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\InstallUtil.exe'
              - '\RegAsm.exe'
              - '\RegSvcs.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
        - OriginalFileName:
              - 'InstallUtil.exe'
              - 'RegAsm.exe'
              - 'RegSvcs.exe'
              - 'REGSVR32.EXE'
              - 'RUNDLL32.EXE'
    selection_cli:
        CommandLine|contains:
            - 'Default.GetString'
            - 'DownloadString'
            - 'FromBase64String'
            - 'ICM '
            - 'IEX '
            - 'Invoke-Command'
            - 'Invoke-Expression'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/p3nt4/PowerShdll/blob/62cfa172fb4e1f7f4ac00ca942685baeb88ff356/README.md