Adversaries may register a rogue Domain Controller to enable manipulation of Active Directory data. DCShadow may be used to create a rogue Domain Controller (DC). DCShadow is a method of manipulating Active Directory (AD) data, including objects and schemas, by registering (or reusing an inactive registration) and simulating the behavior of a DC. (Citation: DCShadow Blog) Once registered, a rogue DC may be able to inject and replicate changes into AD infrastructure for any domain object, including credentials and keys. Registering a rogue DC involves creating a new server and nTDSDSA objects in the Configuration partition of the AD schema, which requires Administrator privileges (either Domain or local to the DC) or the KRBTGT hash. (Citation: Adsecurity Mimikatz Guide) This technique may bypass system logging and security monitors such as security information and event management (SIEM) products (since actions taken on a rogue DC may not be reported to these sensors). (Citation: DCShadow Blog) The technique may also be used to alter and delete replication and other associated metadata to obstruct forensic analysis. Adversaries may also utilize this technique to perform SID-History Injection and/or manipulate AD objects (such as accounts, access control lists, schemas) to establish backdoors for Persistence. (Citation: DCShadow Blog)
Detection of rogue Domain Controller registration and Active Directory replication abuse by correlating: (1) creation/modification of nTDSDSA and server objects in the Configuration partition, (2) unexpected usage of Directory Replication Service SPNs (GC/ or E3514235-4B06-11D1-AB04-00C04FC2DCD2), (3) replication RPC calls (DrsAddEntry, DrsReplicaAdd, GetNCChanges) originating from non-DC hosts, and (4) Kerberos authentication by non-DC machines using DRS-related SPNs. These events in combination, especially from hosts outside the Domain Controllers OU, may indicate DCShadow or rogue DC activity.