4781 Security log · Account Management medium severity low volume

Windows Event ID 4781 — The name of an account was changed

A user or computer account was renamed. OldTargetUserName → NewTargetUserName.

Why event 4781 matters

Renaming built-in accounts (Administrator, Guest) to hide them. Renaming backdoor accounts to mimic legitimate accounts. SamAccountName rename is used in noPac exploitation.

How to detect it

Alert: renaming of Administrator, Guest, DefaultAccount. Alert: new name closely resembles existing admin accounts (typosquatting).

Log source
Security
Advanced Audit Policy — enable the 'Account Management' subcategory (Success and/or Failure).
Fields to pivot on
SubjectUserNameTargetUserNameLogonTypeIpAddressWorkstationName

MITRE ATT&CK mapping

Tactic Technique
Defense Evasion Masquerading (T1036)

Detection queries

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

Sentinel / Defender KQL
SecurityEvent
| where EventID == 4781   // The name of an account was changed
| project TimeGenerated, Computer, SubjectUserName, TargetUserName, LogonType, IpAddress, WorkstationName
| sort by TimeGenerated desc
Splunk SPL
index=* sourcetype="WinEventLog:Security" EventCode=4781
| stats count earliest(_time) as first_seen latest(_time) as last_seen by ComputerName
| sort - count   `# The name of an account was changed — add EventData fields: SubjectUserName, TargetUserName, LogonType, IpAddress`
Hunt event 4781 in Sentinel/Defender →
Build a KQL query for this event in the KQL Query Builder.
Search all event IDs →
Open the interactive Windows Event ID lookup.

Related Account Management events

4720 A user account was created 4722 A user account was enabled 4723 An attempt was made to change an account's password 4724 An attempt was made to reset an account's password 4725 A user account was disabled 4726 A user account was deleted 4728 A member was added to a security-enabled global group 4729 A member was removed from a security-enabled global group 4730 A security-enabled global group was deleted 4731 A security-enabled local group was created 4732 A member was added to a security-enabled local group 4733 A member was removed from a security-enabled local group

Frequently asked questions

What is Windows Event ID 4781?

The name of an account was changed. A user or computer account was renamed. OldTargetUserName → NewTargetUserName.

Which log records event 4781?

Event 4781 is written to the Security channel by Microsoft-Windows-Security-Auditing. Advanced Audit Policy — enable the 'Account Management' subcategory (Success and/or Failure).

What MITRE ATT&CK techniques map to event 4781?

Event 4781 is associated with: Masquerading (T1036).

How do you detect activity around event 4781?

Alert: renaming of Administrator, Guest, DefaultAccount. Alert: new name closely resembles existing admin accounts (typosquatting).