A session was reconnected to a Window Station
An existing Remote Desktop (RDP) or Fast User Switching session was reconnected.
Event ID 4778 logs when a user reconnects to a previously disconnected terminal server or RDP session (`SessionName: RDP-Tcp#...`). It records the client IP address (`ClientAddress`) and workstation name.
Failure Reason / Root Cause:
User resuming an RDP session after network drop or lock screen, or attacker reconnecting to a hijacked RDP session.
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>4778</EventID>
<Version>0</Version>
<Level>0</Level>
<Task>12544</Task>
<Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords>
<TimeCreated SystemTime="2026-07-17T09:54:44.911Z" />
<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 session was reconnected to a Window Station -->
</EventData>
</Event>MITRE ATT&CK mapping
| ID | Technique | Tactic |
|---|---|---|
T1021.001 | Remote Services: Remote Desktop Protocol | Lateral Movement |
Recommended actions
- Monitor for RDP reconnections (`4778`) from IP addresses different from where the session originated (`4624`).
- Enforce idle RDP session timeout disconnect policies across all servers.