A change has been made to the Windows Firewall exception list. A rule was added
A rule was added to the Windows Firewall exception list allowing specific applications or ports.
Event ID 4946 records exception list additions (`Application Name`, `Port`, `Protocol`). This is the classic telemetry generated when `netsh firewall add allowedprogram` or exception rules are executed by installers or post-exploitation scripts to permit outbound exfiltration or inbound C2 connections.
Failure Reason / Root Cause:
Firewall exception rule added (`Application Path` / `Port` allowed through firewall).
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>4946</EventID>
<Version>0</Version>
<Level>0</Level>
<Task>12544</Task>
<Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords>
<TimeCreated SystemTime="2026-07-17T09:54:44.924Z" />
<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 added -->
</EventData>
</Event>MITRE ATT&CK mapping
| ID | Technique | Tactic |
|---|---|---|
T1562.004 | Impair Defenses: Disable or Modify System Firewall | Defense Evasion |
Recommended actions
- Inspect `Application Name` and `Port`. Verify whether unlisted binaries (`powershell.exe`, `cmd.exe`, or unknown `.exe` files in user profiles) were added to the allowed exception list.