Windows ImageLoad of DLL from spoolsv.exe spool drivers subfolders

Flags spoolsv.exe DLL loads originating from Print Spooler x64\3/x64\4 driver folders on Windows.

FreeReviewedSigma · Informational · v5

Product: windows
Category: image_load
Author: FPT.EagleEye, Thomas Patzke (improvements) (SigmaHQ), DRL 1.1
Published: 2021-06-29
Updated: 2026-07-31

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1574Hijack Execution Flow
Persistence
- T1574Hijack Execution Flow
Priv Esc
- T1574Hijack Execution Flow
Defense Evasion
- T1574Hijack Execution Flow
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags DLL loads where the initiating image is spoolsv.exe and the loaded module path matches specific spool driver x64 subfolders. Such behavior can indicate print spooler abuse or persistence attempts that load additional code through the spooler service. It relies on Windows image load telemetry that includes both the initiating Image and the ImageLoaded path for .dll modules.

Reporting behind it

Related detections9 linkedT1574 — drag to rearrange

Suspicious Execution or Load from Fake System32 Directory Imprint (via process_creation)

Suspicious LD_PRELOAD Library Injection via PUMAKIT Userland Rootkit

Windows DLL Search Order Hijacking: Suspicious DLL Writes to App Dependency Folders

Windows Registry Persistence: DbgManagedDebugger Debugger Value Added

Windows Suspicious DLL Deletion in Spooler Driver Folder (PrintNightmare/CVE-2021-1675)

Windows DLL execution via register-cimprovider.exe with -path dll

Windows Registry Printer Driver Installations with Empty Manufacturer Field

Windows Process Creation: Suspicious SetupComplete.cmd execution for CVE-2019-1378 exploitation

Windows regsvr32 Executes DLL with Uncommon Extension in Command Line

Windows ImageLoad of DLL from spoolsv.exe spool drivers subfolders

Pivot detection · T1574 · 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-spooler-spoolsv-exe-loads-dll-from-spool-drivers-subdirectories-02fb90de

title: Windows ImageLoad of DLL from spoolsv.exe spool drivers subfolders
id: fc01012f-a4a4-4e18-a25e-8b30ee9320c3
status: test
description: This rule flags DLL loads where the initiating image is spoolsv.exe and the loaded module path matches specific spool driver x64 subfolders. Such behavior can indicate print spooler abuse or persistence attempts that load additional code through the spooler service. It relies on Windows image load telemetry that includes both the initiating Image and the ImageLoaded path for .dll modules.
references:
  - https://web.archive.org/web/20210629055600/https://github.com/hhlxf/PrintNightmare/
  - https://github.com/ly4k/SpoolFool
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2021/Exploits/CVE-2021-1675/image_load_exploit_cve_2021_1675_spoolsv_dll_load.yml
author: FPT.EagleEye, Thomas Patzke (improvements), Huntrule Team
date: 2021-06-29
modified: 2022-06-02
tags:
  - attack.persistence
  - attack.privilege-escalation
  - attack.execution
  - attack.stealth
  - attack.t1574
  - cve.2021-1675
  - cve.2021-34527
  - detection.emerging-threats
logsource:
  category: image_load
  product: windows
detection:
  selection:
    Image|endswith: \spoolsv.exe
    ImageLoaded|contains:
      - \Windows\System32\spool\drivers\x64\3\
      - \Windows\System32\spool\drivers\x64\4\
    ImageLoaded|endswith: .dll
  condition: selection
falsepositives:
  - Loading of legitimate driver
level: informational
license: DRL-1.1
related:
  - id: 02fb90de-c321-4e63-a6b9-25f4b03dfd14
    type: derived

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