DMSA Service Account Created in Specific OUs - PowerShell

Severity: medium
Author: Swachchhanda Shrawan Poudel (Nextron Systems)
Source: upstream

Detects the creation of a dMSA service 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.

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1078.002` Valid Accounts: Domain Accounts
Persistence	`T1078.002` Valid Accounts: Domain Accounts, `T1098` Account Manipulation
Privilege Escalation	`T1078.002` Valid Accounts: Domain Accounts, `T1098` Account Manipulation
Defense Evasion	`T1078.002` Valid Accounts: Domain Accounts

Event coverage

Provider	Event ID	Title
PowerShell	4104	Creating Scriptblock text (MessageNumber of MessageTotal).

Stages and Predicates

Stage 1: `selection`

ScriptBlockText|contains: -CreateDelegatedServiceAccount
ScriptBlockText|contains: -path
ScriptBlockText|contains: New-ADServiceAccount

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`ScriptBlockText`	match	`-CreateDelegatedServiceAccount` `-path` `New-ADServiceAccount`

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.

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