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Windows rundll32.exe Using ShellExecute via ShellDispatch.dll Functionality

Alerts on rundll32.exe command lines referencing RunDll_ShellExecuteW, suggesting ShellDispatch.dll ShellExecute-based execution.

FreeUnreviewedSigmamediumv1
title: Windows rundll32.exe Using ShellExecute via ShellDispatch.dll Functionality
id: db4ffe90-252f-455d-8f28-6150e471b44c
status: test
description: This rule flags process creations where rundll32.exe (by Image ending with \rundll32.exe and OriginalFileName) is launched with a command line containing RunDll_ShellExecuteW. This can indicate attempt to use ShellDispatch.dll-related execution paths to invoke arbitrary binary execution through ShellExecute. Telemetry relies on Windows process creation events with Image/OriginalFileName and the full CommandLine content.
references:
  - https://www.hexacorn.com/blog/2023/06/07/this-lolbin-doesnt-exist/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_rundll32_shelldispatch_potential_abuse.yml
author: X__Junior (Nextron Systems), Huntrule Team
date: 2023-06-20
tags:
  - attack.execution
  - attack.stealth
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    - Image|endswith: \rundll32.exe
    - OriginalFileName: RUNDLL32.EXE
  selection_cli:
    CommandLine|contains: RunDll_ShellExecuteW
  condition: all of selection_*
falsepositives:
  - Unlikely
level: medium
license: DRL-1.1
related:
  - id: 82343930-652f-43f5-ab70-2ee9fdd6d5e9
    type: derived

What it detects

This rule flags process creations where rundll32.exe (by Image ending with \rundll32.exe and OriginalFileName) is launched with a command line containing RunDll_ShellExecuteW. This can indicate attempt to use ShellDispatch.dll-related execution paths to invoke arbitrary binary execution through ShellExecute. Telemetry relies on Windows process creation events with Image/OriginalFileName and the full CommandLine content.

Known false positives

  • Unlikely

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.