Event log automatic backup completed

// EVENT DEFINITION:

The security event log was automatically archived and cleared based on retention policy.

// DETAILED TELEMETRY & CONTEXT:

Event ID 1105 occurs when Windows automatically backs up the event log to an archive file (`Archive-Security-*.evtx`) upon reaching capacity when configured to 'Archive the log when full, do not overwrite events'.

[ ! ]Failure Reason / Root Cause Analysis

Standard automated log rotation and archiving behavior configured via Group Policy.

Operational Metadata & Applicability

Log Category:Event Log

Audit Type Classification:Success Audit

Supported Operating Systems:Windows Server 2016, 2019, 2022 / Windows Client 10, 11 (Enterprise / Pro)

Threat Hunting Keywords:

log backuparchivelog rotationevtx backupcapacity management

Mitigation Playbook & Recommended SOC Actions

•Ensure automated log collection agents immediately collect and ingest newly generated archive files.

Representative Windows Event XML Schema

<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>1105</EventID>
    <Version>0</Version>
    <Level>0</Level>
    <Task>12544</Task>
    <Opcode>0</Opcode>
    <Keywords>0x8020000000000000</Keywords>
    <TimeCreated SystemTime="2026-07-17T09:54:44.243Z" />
    <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 Event log automatic backup completed -->
  </EventData>
</Event>

Correlated / Related Security Event IDs

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