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dMSA Account Creation by an Unusual User

Detects the creation of a delegated Managed Service Account by an unusual subject account. Attackers can abuse the dMSA account migration feature to elevate privileges abusing weak persmission allowing users child objects rights or msDS-DelegatedManagedServiceAccount rights.

Rule type: new_terms
Rule indices:

  • winlogbeat-*
  • logs-system.security*
  • logs-windows.forwarded*

Rule Severity: high
Risk Score: 73
Runs every:
Searches indices from: now-9m
Maximum alerts per execution: ?
References:

Tags:

  • Domain: Endpoint
  • OS: Windows
  • Use Case: Threat Detection
  • Tactic: Privilege Escalation
  • Use Case: Active Directory Monitoring
  • Data Source: Active Directory
  • Data Source: Windows Security Event Logs
  • Resources: Investigation Guide

Version: ?
Rule authors:

  • Elastic

Rule license: Elastic License v2

  • Examine the winlog.event_data.SubjectUserName field and verify if he is allowed and used to create dMSA accounts.
  • Examine all Active Directory modifications performed by the winlog.event_data.SubjectUserName.
  • Investigate the history of the identified user account to determine if there are any other suspicious activities or patterns of behavior.
  • Collaborate with the IT or security team to determine if the changes were authorized or if further action is needed to secure the environment.
  • Migration of legacy service accounts using delegated managed service account.
  • Immediately disable the winlog.event_data.SubjectUserName account and revert all changes performed by that account.
  • Identify and isolate the source machines from where the SubjectUserName is authenticating.
  • Reset passwords for all accounts that were potentially affected or had their permissions altered, focusing on privileged accounts to prevent adversaries from regaining access.
  • Escalate the incident to the security operations center (SOC) or incident response team for further investigation and to determine the scope of the breach, including identifying any other compromised systems or accounts.
  • Review and update access control policies and security configurations to prevent similar attacks, ensuring that only authorized personnel have the ability to modify critical Active Directory objects or create OU child objects.
event.code:5137 and winlog.event_data.ObjectClass:"msDS-DelegatedManagedServiceAccount"

Framework: MITRE ATT&CK