Rundll32.exe DLL Export Calls by Ordinal (Windows Process Creation)

Detects rundll32.exe commands that specify DLL exports by ordinal using “.dll #” syntax.

FreeReviewedSigma · Medium · v5

Product: windows
Category: process_creation
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2019-10-22
Updated: 2026-07-31

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1218.011Rundll32
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies process creation events where rundll32.exe loads a DLL export using an ordinal notation (e.g., strings containing ',#' and '.dll #' or '.ocx #'). Using ordinal-based export calls can obscure intent and is a common technique in stealthy execution chains. It relies on Windows process creation telemetry, matching the Image/OriginalFileName for rundll32.exe and specific patterns in the CommandLine. Optional exclusions reduce matches for known benign tooling patterns.

Reporting behind it

Related detections9 linkedT1218.011 — drag to rearrange

Malicious Lunar Spider Loader Execution via rundll32 (via process_creation)

Malicious SYSTEM Persistence via Scheduled Task Running rundll32 at Startup (via process_creation)

Malicious Rundll32 Executing Image File as DLL

Suspicious Scheduled Task Executing Rundll32 DLL Export by Ordinal

Malicious Renamed Rundll32 Copied to Temp via Xcopy

Suspicious rundll32 Executing DLL from ProgramData (via process_creation)

Suspicious Rundll32 Loading DLL From Public or ProgramData Path via Process Creation (via process_creation)

Malicious LSASS Credential Dump via Rundll32 Comsvcs MiniDump via Process Creation (via process_creation)

Suspicious Rundll32 Execution Without a DLL Reference via Process Creation (via process_creation)

Rundll32.exe DLL Export Calls by Ordinal (Windows Process Creation)

Pivot detection · T1218.011 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

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

windows-rundll32-exe-loads-dll-exports-by-ordinal-in-command-line-e79a9e79

title: Rundll32.exe DLL Export Calls by Ordinal (Windows Process Creation)
id: cfa15580-4c53-4cdd-a83a-43ec8652545e
status: stable
description: "This rule identifies process creation events where rundll32.exe loads a DLL export using an ordinal notation (e.g., strings containing ',#' and '.dll #' or '.ocx #'). Using ordinal-based export calls can obscure intent and is a common technique in stealthy execution chains. It relies on Windows process creation telemetry, matching the Image/OriginalFileName for rundll32.exe and specific patterns in the CommandLine. Optional exclusions reduce matches for known benign tooling patterns."
references:
  - https://web.archive.org/web/20200530031906/https://techtalk.pcmatic.com/2017/11/30/running-dll-files-malware-analysis/
  - https://github.com/Neo23x0/DLLRunner
  - https://twitter.com/cyb3rops/status/1186631731543236608
  - https://www.welivesecurity.com/2022/03/01/isaacwiper-hermeticwizard-wiper-worm-targeting-ukraine/
  - https://github.com/SigmaHQ/sigma/blob/master/rules-threat-hunting/windows/process_creation/proc_creation_win_rundll32_by_ordinal.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2019-10-22
modified: 2024-07-16
tags:
  - attack.stealth
  - attack.t1218.011
  - detection.threat-hunting
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    - Image|endswith: \rundll32.exe
    - OriginalFileName: RUNDLL32.EXE
  selection_cli:
    CommandLine|contains:
      - ",#"
      - ", #"
      - ".dll #"
      - ".ocx #"
  filter_optional_edge:
    CommandLine|contains|all:
      - EDGEHTML.dll
      - "#141"
  filter_optional_vsbuild_dll:
    ParentImage|contains:
      - \Msbuild\Current\Bin\
      - \VC\Tools\MSVC\
      - \Tracker.exe
    CommandLine|contains:
      - \FileTracker32.dll,#1
      - \FileTracker32.dll",#1
      - \FileTracker64.dll,#1
      - \FileTracker64.dll",#1
  condition: all of selection_* and not 1 of filter_optional_*
falsepositives:
  - False positives depend on scripts and administrative tools used in the monitored environment.
  - Windows control panel elements have been identified as source (mmc).
level: medium
license: DRL-1.1
related:
  - id: e79a9e79-eb72-4e78-a628-0e7e8f59e89c
    type: derived

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