Windows Security Mitigations: Unsigned DLL Blocked from User-Writable Paths

Alerts on blocked unsigned DLL loads targeting public, downloads, desktop, or temp directories in Windows Security Mitigations logs.

FreeReviewedSigma · High · v2

Product: windows
Service: security-mitigations
Author: Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-08-03
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1574.001DLL
Persistence
- T1574.001DLL
Priv Esc
- T1574.001DLL
Defense Evasion
- T1574.001DLL
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags security-mitigations events where processes are blocked from loading unsigned DLLs located in common suspicious, user-writable locations (e.g., Users\Public, PerfLogs, Desktop, Downloads, and local Temp directories). Attackers often place unsigned components in these paths to execute or persist code while evading signature validation. Detection relies on Windows Security Mitigations telemetry (EventID 11 and 12) that records the blocked DLL load attempts and the associated image path.

Reporting behind it

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Windows Security Mitigations: Unsigned DLL Blocked from User-Writable Paths

Pivot detection · T1574.001 · 9 related

Changelog

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-security-mitigations-blocked-unsigned-dlls-loaded-from-suspicious-paths-8289bf8c

title: "Windows Security Mitigations: Unsigned DLL Blocked from User-Writable Paths"
id: 35d60523-6dad-402d-81df-fefde5a75819
status: test
description: This rule flags security-mitigations events where processes are blocked from loading unsigned DLLs located in common suspicious, user-writable locations (e.g., Users\Public, PerfLogs, Desktop, Downloads, and local Temp directories). Attackers often place unsigned components in these paths to execute or persist code while evading signature validation. Detection relies on Windows Security Mitigations telemetry (EventID 11 and 12) that records the blocked DLL load attempts and the associated image path.
references:
  - https://github.com/nasbench/EVTX-ETW-Resources/blob/45fd5be71a51aa518b1b36d4e1f36af498084e27/ETWEventsList/CSV/Windows11/21H2/W11_21H2_Pro_20220719_22000.795/Providers/Microsoft-Windows-Security-Mitigations.csv
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/security_mitigations/win_security_mitigations_unsigned_dll_from_susp_location.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-08-03
modified: 2022-09-28
tags:
  - attack.privilege-escalation
  - attack.persistence
  - attack.execution
  - attack.stealth
  - attack.t1574.001
logsource:
  product: windows
  service: security-mitigations
detection:
  selection:
    EventID:
      - 11
      - 12
    ImageName|contains:
      - \Users\Public\
      - \PerfLogs\
      - \Desktop\
      - \Downloads\
      - \AppData\Local\Temp\
      - C:\Windows\TEMP\
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 8289bf8c-4aca-4f5a-9db3-dc3d7afe5c10
    type: derived

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