AD replication failure started.
Replication failures can indicate network issues, DCSync disruption, or USN rollback attacks.
Alert: sustained replication failures between specific DCs. Investigate for split-brain or attack scenarios.
SubjectUserNameTargetUserNameLogonTypeIpAddressWorkstationName Starting points — adapt the log source, projected fields and thresholds for your environment.
SecurityEvent
| where EventID == 4935 // Replication failure begins
| project TimeGenerated, Computer, SubjectUserName, TargetUserName, LogonType, IpAddress, WorkstationName
| sort by TimeGenerated desc
index=* sourcetype="WinEventLog:Security" EventCode=4935
| stats count earliest(_time) as first_seen latest(_time) as last_seen by ComputerName
| sort - count `# Replication failure begins — add EventData fields: SubjectUserName, TargetUserName, LogonType, IpAddress`
Replication failure begins. AD replication failure started.
Event 4935 is written to the Security channel by Microsoft-Windows-Security-Auditing. Advanced Audit Policy — enable the 'DS Access' subcategory (Success and/or Failure).
Alert: sustained replication failures between specific DCs. Investigate for split-brain or attack scenarios.