A change has been made to the Windows Firewall exception list. A rule was deleted
An existing firewall rule or exception was removed from the Windows Firewall configuration.
Event ID 4948 logs rule deletions (`Rule Name deleted`). Threat actors sometimes delete strict outbound block rules or remove administrative isolation exceptions to permit unrestricted network egress.
Failure Reason / Root Cause:
Deletion of Windows Firewall rule (`RuleName` removed by `SubjectUserName`).
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>4948</EventID>
<Version>0</Version>
<Level>0</Level>
<Task>12544</Task>
<Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords>
<TimeCreated SystemTime="2026-07-17T09:54:44.925Z" />
<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 A change has been made to the Windows Firewall exception list. A rule was deleted -->
</EventData>
</Event>MITRE ATT&CK mapping
| ID | Technique | Tactic |
|---|---|---|
T1562.004 | Impair Defenses: Disable or Modify System Firewall | Defense Evasion |
Recommended actions
- Verify that deleted rules did not enforce required network segmentation or outbound restriction policies.