Potential Renamed Rundll32 Execution

Description

Detects when 'DllRegisterServer' is called in the commandline and the image is not rundll32. This could mean that the 'rundll32' utility has been renamed in order to avoid detection

Query · sigma

selection:
  CommandLine|contains: DllRegisterServer
filter:
  Image|endswith: \rundll32.exe
condition: selection and not filter

Known false positives

  • Unlikely
Raw source Potential Renamed Rundll32 Execution · Sigma
Esc
Published by SigmaHQ/sigma ↗, licensed under Detection Rule License 1.1 ↗. Reproduced here unmodified. 
title: Potential Renamed Rundll32 Execution
id: 2569ed8c-1147-498a-9b8c-2ad3656b10ed
related:
    - id: 0ba1da6d-b6ce-4366-828c-18826c9de23e
      type: derived
status: test
description: Detects when 'DllRegisterServer' is called in the commandline and the image is not rundll32. This could mean that the 'rundll32' utility has been renamed in order to avoid detection
references:
    - https://twitter.com/swisscom_csirt/status/1331634525722521602?s=20
    - https://app.any.run/tasks/f74c5157-8508-4ac6-9805-d63fe7b0d399/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-22
modified: 2023-02-03
tags:
    - attack.execution
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains: 'DllRegisterServer'
    filter:
        Image|endswith: '\rundll32.exe'
    condition: selection and not filter
falsepositives:
    - Unlikely
level: high

Detection rules belong to the projects that publish them and remain under their own licenses. This site indexes and links to them; it claims no rights in them.