Template -- Rundll32 loading a DLL from a user-writable path

SIGMA detection rule by WinstonRedGuard -- sigma plugin canonical templates · Unknown

Canonical Sigma detection template for MITRE ATT&CK T1218.011 (System Binary Proxy Execution: Rundll32). Detects rundll32 loading a DLL from a common user-writable location, which is unusual for ordinary system DLL execution. The DLL entry-point delimiter narrows the signal to the normal rundll32 invocation shape. Synthetic exemplar from the WinstonRedGuard threat-intel corpus -- no actor binding; review and bind to your environment before deployment.

title: Template -- Rundll32 loading a DLL from a user-writable path
id: bfa09052-9fcb-58a6-9801-328bbb75c092
status: experimental
description: >-
  Canonical Sigma detection template for MITRE ATT&CK T1218.011 (System
  Binary Proxy Execution: Rundll32). Detects rundll32 loading a DLL from a
  common user-writable location, which is unusual for ordinary system DLL
  execution. The DLL entry-point delimiter narrows the signal to the normal
  rundll32 invocation shape. Synthetic exemplar from the WinstonRedGuard
  threat-intel corpus -- no actor binding; review and bind to your environment
  before deployment.
references:
- https://attack.mitre.org/techniques/T1218/011/
author: WinstonRedGuard -- sigma plugin canonical templates
date: '2026-09-16'
logsource:
  category: process_creation
  product: windows
detection:
  selection_rundll32:
    Image|endswith: '\rundll32.exe'
  selection_user_writable_dll:
    CommandLine|contains:
    - '\Users\'
    - '\ProgramData\'
    - '\Windows\Temp\'
    - '\Windows\Tasks\'
  selection_dll_entrypoint:
    CommandLine|contains: '.dll,'
  condition: selection_rundll32 and selection_user_writable_dll and selection_dll_entrypoint
falsepositives:
- Per-user installed software that invokes a plugin DLL through rundll32 from
  a user profile, particularly legacy desktop applications or updater helpers
- Enterprise management software that stages a signed DLL under ProgramData or
  Windows Temp and invokes a documented rundll32 export during installation
- Forensic or remediation tooling that deliberately uses rundll32 to load an
  investigative DLL from a temporary working directory
level: medium
tags:
- attack.t1218.011
- wrg.template
- wrg.tactic.stealth

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76d3c09f-1b12-4ec3-a92f-9962f47fd5c1

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Executable code, not a declarative rule

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