A local security group was deleted.
Destruction of local groups disrupts access controls.
Alert: deletion of Administrators, Backup Operators, or Remote Desktop Users groups.
SubjectUserNameTargetUserNameLogonTypeIpAddressWorkstationName Starting points — adapt the log source, projected fields and thresholds for your environment.
SecurityEvent
| where EventID == 4734 // A security-enabled local group was deleted
| project TimeGenerated, Computer, SubjectUserName, TargetUserName, LogonType, IpAddress, WorkstationName
| sort by TimeGenerated descindex=* sourcetype="WinEventLog:Security" EventCode=4734
| stats count earliest(_time) as first_seen latest(_time) as last_seen by ComputerName
| sort - count `# A security-enabled local group was deleted — add EventData fields: SubjectUserName, TargetUserName, LogonType, IpAddress`A security-enabled local group was deleted. A local security group was deleted.
Event 4734 is written to the Security channel by Microsoft-Windows-Security-Auditing. Advanced Audit Policy — enable the 'Account Management' subcategory (Success and/or Failure).
Alert: deletion of Administrators, Backup Operators, or Remote Desktop Users groups.