Windows Event ID 4930 — An Active Directory replica source naming context was modified — SecOps Tools

Why event 4930 matters

Modification of replication configuration may affect AD replication topology. Attackers may modify to disrupt replication.

How to detect it

Alert: unexpected modifications to replication configuration outside planned AD changes.

Log source

Security

Advanced Audit Policy — enable the 'DS Access' subcategory (Success and/or Failure).

Fields to pivot on

SubjectUserNameTargetUserNameLogonTypeIpAddressWorkstationName

Detection queries

Starting points — adapt the log source, projected fields and thresholds for your environment.

Sentinel / Defender KQL

SecurityEvent
| where EventID == 4930   // An Active Directory replica source naming context was modified
| project TimeGenerated, Computer, SubjectUserName, TargetUserName, LogonType, IpAddress, WorkstationName
| sort by TimeGenerated desc

Splunk SPL

index=* sourcetype="WinEventLog:Security" EventCode=4930
| stats count earliest(_time) as first_seen latest(_time) as last_seen by ComputerName
| sort - count   `# An Active Directory replica source naming context was modified — add EventData fields: SubjectUserName, TargetUserName, LogonType, IpAddress`

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Related DS Access events

4662 An operation was performed on an object 4928 An Active Directory replica source naming context was established 4929 An Active Directory replica source naming context was removed 4932 Synchronization of a replica of an Active Directory naming context has begun 4933 Synchronization of a replica of an Active Directory naming context has ended 4934 Attributes of an Active Directory object were replicated 4935 Replication failure begins 4936 Replication failure ends 4937 A lingering object was removed from the replica 5136 A directory service object was modified 5137 A directory service object was created 5138 A directory service object was undeleted

Frequently asked questions

What is Windows Event ID 4930?

An Active Directory replica source naming context was modified. A replication naming context was modified. Part of normal AD configuration changes.

Which log records event 4930?

Event 4930 is written to the Security channel by Microsoft-Windows-Security-Auditing. Advanced Audit Policy — enable the 'DS Access' subcategory (Success and/or Failure).

How do you detect activity around event 4930?

Alert: unexpected modifications to replication configuration outside planned AD changes.