New DMSA Service Account Created in Specific OUs — Sigma Rule

Rule metadata and linked tags

Author: Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: medium. Source dates: 2025-05-24 / not supplied.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 38869ffe9c13cd0cba9f7a1895edc876b4ad3e7df009b98b7f251a66987440cf

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: New DMSA Service Account Created in Specific OUs
id: 0ea8db81-2ff6-4525-9448-33bbe7effc13
related:
    - id: e15bc294-ae2a-45ad-b7d6-637b33868bde # Windows Security Creation of New MsDS-DelegatedManagedServiceAccount (DMSA) Object
      type: similar
    - id: 02122374-b74e-495c-b285-9e4da973f3d6 # ScriptBlockText Detection
      type: similar
status: experimental
description: |
    Detects the creation of a dMSASvc account using the New-ADServiceAccount cmdlet in certain OUs.
    The fact that the Cmdlet is used to create a dMSASvc account in a specific OU is highly suspicious.
    It is a pattern trying to exploit the BadSuccessor privilege escalation vulnerability in Windows Server 2025.
    On top of that, if the user that is creating the dMSASvc account is not a legitimate administrator or does not have the necessary permissions,
    it is a strong signal of an attempted or successful abuse of the BaDSuccessor vulnerability for privilege escalation within the Windows Server 2025 Active Directory environment.
references:
    - https://www.akamai.com/blog/security-research/abusing-bad-successor-for-privilege-escalation-in-active-directory
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-05-24
tags:
    - attack.privilege-escalation
    - attack.initial-access
    - attack.persistence
    - attack.stealth
    - attack.t1078.002
    - attack.t1098
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\powershell.exe'
              - '\pwsh.exe'
              - '\powershell_ise.exe'
        - OriginalFileName:
              - 'powershell.exe'
              - 'pwsh.dll'
              - 'powershell_ise.exe'
    selection_cli:
        CommandLine|contains|all:
            - 'New-ADServiceAccount'
            - '-CreateDelegatedServiceAccount'
            - '-path'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.akamai.com/blog/security-research/abusing-bad-successor-for-privilege-escalation-in-active-directory