Suspicious modification of a fake domain controller SPN (DCshadow) (Directory Services)

title: Suspicious modification of a fake domain controller SPN (DCshadow) (Directory Services)
description: Detects scenarios where an attacker update the Service Principal Name (SPN) of a computer account in order to perform "Kerberos redirection" and escalate privileges.
requirements: auditing SACL ("Write all properties") must be placed on the OU to monitor using the Active Directory console (https://www.manageengine.com/products/active-directory-audit/active-directory-auditing-configuration-guide-configure-object-level-auditing-manually.html).
references:
- https://github.com/mdecrevoisier/EVTX-to-MITRE-Attack/tree/master/TA0003-Persistence/T1098.xxx-Account%20manipulation
- https://www.ired.team/offensive-security-experiments/active-directory-kerberos-abuse/t1207-creating-rogue-domain-controllers-with-dcshadow
- https://medium.com/@maarten.goet/dcshadow-detecting-a-rogue-domain-controller-replicating-malicious-changes-to-your-active-1e22440df9ad
- https://github.com/AlsidOfficial/UncoverDCShadow
- https://github.com/shellster/DCSYNCMonitor
- https://blog.alsid.eu/dcshadow-explained-4510f52fc19d
- https://stealthbits.com/blog/detecting-dcshadow-with-event-logs/
- https://www.labofapenetrationtester.com/2018/05/dcshadow-sacl.html
- https://blog.stealthbits.com/creating-persistence-with-dcshadow/
- https://book.hacktricks.xyz/windows/active-directory-methodology/dcshadow
tags:
- attack.persistence
- attack.t1098 # Account Manipulation 
author: mdecrevoisier
status: experimental
logsource:
  product: windows
  service: security
detection:
  selection:
    EventID: 5136
    AttributeLDAPDisplayName: servicePrincipalName
    ObjectClas: computer
    OperationType: '%%14674' # Value is added
    AttributeValue|startswith: 'GC/'
  condition: selection
falsepositives:
- Rare administrator modifications on user objects
level: high