Detection rules › Sigma

New DMSA Service Account Created in Specific OUs

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

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.

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1078.002 Valid Accounts: Domain Accounts
PersistenceT1078.002 Valid Accounts: Domain Accounts, T1098 Account Manipulation
Privilege EscalationT1078.002 Valid Accounts: Domain Accounts, T1098 Account Manipulation
Defense EvasionT1078.002 Valid Accounts: Domain Accounts

Event coverage

ProviderEvent IDTitle
Sysmon1Process creation

Stages and Predicates

Stage 1: all of selection_img

or:
Image|endswith: '\powershell.exe'
Image|endswith: '\powershell_ise.exe'
Image|endswith: '\pwsh.exe'
OriginalFileName: powershell.exe
OriginalFileName: powershell_ise.exe
OriginalFileName: pwsh.dll

Stage 2: all of selection_cli

CommandLine|contains: -CreateDelegatedServiceAccount
CommandLine|contains: -path
CommandLine|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.

FieldKindValues
CommandLinematch
  • -CreateDelegatedServiceAccount
  • -path corpus 2 (sigma 2)
  • New-ADServiceAccount
Imageends_with
  • \powershell.exe corpus 143 (sigma 143)
  • \powershell_ise.exe corpus 27 (sigma 27)
  • \pwsh.exe corpus 140 (sigma 140)
OriginalFileNameeq
  • powershell.exe corpus 8 (sigma 8)
  • powershell_ise.exe corpus 6 (sigma 6)
  • pwsh.dll corpus 72 (sigma 68, splunk 4)