Certificate Services denied a certificate request
AD CS rejected a certificate enrollment request due to policy or template restriction.
Event ID 4888 logs rejected certificate requests (`Request ID`). High volumes of denied certificate enrollment requests from a single host or user indicate active scanning and fuzzing of AD CS certificate templates (`Certipy find / req`).
Failure Reason / Root Cause:
Certificate enrollment request denied by CA policy or permission check (`Disposition message`).
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>4888</EventID>
<Version>0</Version>
<Level>0</Level>
<Task>12544</Task>
<Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords>
<TimeCreated SystemTime="2026-07-17T09:54:44.920Z" />
<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 Certificate Services denied a certificate request -->
</EventData>
</Event>MITRE ATT&CK mapping
| ID | Technique | Tactic |
|---|---|---|
T1046 | Network Service Discovery | Discovery |
Recommended actions
- Review the `Requester` and `CertificateTemplate` for repeated failed enrollment attempts.