AppLocker: EXE or DLL blocked from running
An executable or DLL binary was blocked from execution by AppLocker application control rules.
Event ID 8004 (`Microsoft-Windows-AppLocker/EXE and DLL`) records when AppLocker blocks an unauthorized executable or DLL (`FilePath`, `RuleName: Deny`). High-priority alert indicating that a user or automated malware payload attempted to launch unapproved software.
Failure Reason / Root Cause:
Binary execution blocked by AppLocker enforcement (`FilePath` denied by rule).
Raw Event XML snippet
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Microsoft-Windows-Security-Auditing" Guid="{54849625-5478-4994-A5BA-3E3B0328C30D}" />
<EventID>8004</EventID>
<Version>0</Version>
<Level>0</Level>
<Task>12544</Task>
<Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords>
<TimeCreated SystemTime="2026-07-17T09:54:44.944Z" />
<EventRecordID>1048576</EventRecordID>
<Correlation />
<Execution ProcessID="612" ThreadID="1024" />
<Channel>Security</Channel>
<Computer>DC01.enterprise.internal</Computer>
<Security />
</System>
<EventData>
<Data Name="SubjectUserSid">S-1-5-18</Data>
<Data Name="SubjectUserName">SYSTEM</Data>
<Data Name="SubjectDomainName">NT AUTHORITY</Data>
<Data Name="SubjectLogonId">0x3e7</Data>
<!-- Event telemetry fields specific to AppLocker: EXE or DLL blocked from running -->
</EventData>
</Event>MITRE ATT&CK mapping
| ID | Technique | Tactic |
|---|---|---|
T1204.002 | User Execution: Malicious File | Execution |
T1553 | Subvert Trust Controls | Defense Evasion |
Recommended actions
- Inspect `FilePath` and `Full File Hash`. Retrieve the blocked binary from the endpoint to analyze whether it represents malware, unauthorized portable utilities, or a legitimate software update.