Detection rules › Sigma

AppLocker Application Would Have Been Blocked

Status
experimental
Severity
medium
Log source
product windows, service applocker
Author
heyyanu
Source
github.com/SigmaHQ/sigma

Detects when AppLocker "Audit only" enforcement mode reports that an Application, DLL, Script, MSI, or Packaged-App would have been blocked if AppLocker "Enforce rules" enforcement mode was enabled.

Known false positives

  • Expected during AppLocker policy testing and audit mode deployments

MITRE ATT&CK coverage

Telemetry coverage

Rule body

title: AppLocker Application Would Have Been Blocked
id: 557e3bd3-7f21-495d-8d50-7c8bdfb8041c
status: experimental
description: |
    Detects when AppLocker "Audit only" enforcement mode reports that an Application, DLL, Script, MSI, or Packaged-App would have been blocked if AppLocker "Enforce rules" enforcement mode was enabled.
references:
    - https://learn.microsoft.com/en-us/windows/security/application-security/application-control/windows-defender-application-control/applocker/what-is-applocker
    - https://learn.microsoft.com/en-us/windows/security/application-security/application-control/windows-defender-application-control/applocker/using-event-viewer-with-applocker
    - https://www.splunk.com/en_us/blog/security/deploy-test-monitor-mastering-microsoft-applocker-part-2.html
    - https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/ee844150(v=ws.11)
author: heyyanu
date: 2026-03-26
tags:
    - attack.execution
    - attack.t1204.002
    - attack.t1059.001
    - attack.t1059.003
    - attack.t1059.005
    - attack.t1059.006
    - attack.t1059.007
logsource:
    product: windows
    service: applocker
detection:
    selection:
        EventID:
            - 8003 # EXE and DLL would have been blocked
            - 8006 # MSI and Script would have been blocked
            - 8021 # Packaged app execution would have been blocked
            - 8024 # Packaged app deployment would have been blocked
    condition: selection
falsepositives:
    - Expected during AppLocker policy testing and audit mode deployments
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    EventID:
        - 8003
        - 8006
        - 8021
        - 8024