Detect Rogue Domain Controller in CrowdStrike LogScale
Adversaries may register a rogue Domain Controller to enable manipulation of Active Directory data. 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. Once registered, a rogue DC may inject and replicate changes into AD infrastructure for any domain object, including credentials, group memberships, and SID history. Registering a rogue DC involves creating new server and nTDSDSA objects in the Configuration partition of the AD schema, which requires Administrator privileges (Domain or local DC) or the KRBTGT hash. This technique bypasses most SIEM sensors since changes are pushed directly via AD replication without touching standard audit paths. Mimikatz implements DCShadow via the lsadump::dcshadow module, requiring two concurrent sessions: one running as SYSTEM to register the rogue DC and stage changes, and one running as a domain admin to trigger the replication push.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1207 Rogue Domain Controller
- Canonical reference
- https://attack.mitre.org/techniques/T1207/
LogScale Detection Query
union(
{
#event_simpleName=ProcessRollup2
| CommandLine=/(?i)(lsadump::dcshadow|dcshadow\s+\/(push|start|domain|object|attribute))/
| DetectionBranch:="MimikatzDCShadow"
| AlertReason:="Mimikatz DCShadow command-line arguments detected on endpoint"
},
{
EventID=5137
| Message=/nTDSDSA|NTDS\s+Settings/
| DetectionBranch:="RogueDCObjectCreated"
| AlertReason:="nTDSDSA object created in AD Configuration partition - possible rogue DC registration"
},
{
EventID in (4928, 4929)
| case {
EventID=4928
| DetectionBranch:="ReplicationSourceEstablished"
| AlertReason:="AD replica source naming context established - verify this is a legitimate DC" ;
EventID=4929
| DetectionBranch:="ReplicationSourceRemoved"
| AlertReason:="AD replica source naming context removed - verify expected decommission" ;
*
| DetectionBranch:="ReplicationSourceChange"
| AlertReason:="AD replication source change detected" ;
}
},
{
EventID=4742
| Message=/GC\/|E3514235-4B06-11D1-AB04-00C04FC2DCD2/
| DetectionBranch:="DCLikeSPNAdded"
| AlertReason:="Computer account modified with Global Catalog or DRSUapi SPN - possible rogue DC registration"
}
)
| table([_time, ComputerName, UserName, CommandLine, EventID, DetectionBranch, AlertReason])
| sort(field=_time, order=desc)CrowdStrike LogScale (CQL) query detecting DCShadow / Rogue Domain Controller (T1207) attacks across four branches. Branch 1 uses Falcon EDR ProcessRollup2 events to detect Mimikatz DCShadow command-line arguments. Branches 2-4 require Windows Security Event Log collection via Falcon LogScale Collector, detecting nTDSDSA object creation (Event 5137), AD replication source context changes (Events 4928/4929), and computer account modification with DC-like Global Catalog or DRSUapi SPNs (Event 4742).
Data Sources
Required Tables
False Positives & Tuning
- Legitimate DC promotion via Install-ADDSDomainController or Server Manager generates ProcessRollup2 events for Windows setup binaries and Security Events 5137, 4928, 4929 — baseline known DC hostnames in ComputerName and filter against CMDB before triaging
- AD migration tooling such as Microsoft ADMT generating computer account modifications (Event 4742) with temporary SPNs during cross-forest or cross-domain object migration operations
- Authorized red team or purple team operations using Mimikatz DCShadow — implement asset tagging on known red team systems and exclude those ComputerName values from production alerting dashboards during engagement windows
Other platforms for T1207
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Enumerate Existing DC Registrations (Baseline / Forensic Recon)
Expected signal: Sysmon Event ID 1: powershell.exe process creation with LDAP query arguments. No directory service modification events (read-only). PowerShell ScriptBlock Log Event ID 4104 capturing the LDAP filter targeting nTDSDSA objectClass. No network connections beyond standard LDAP to port 389.
- Test 2DCShadow Stage Phase — Register Rogue DC (Mimikatz SYSTEM Session)
Expected signal: Sysmon Event ID 1: mimikatz.exe process creation under NT AUTHORITY\SYSTEM context, CommandLine containing lsadump::dcshadow. Windows Security Event ID 5137 on Domain Controllers: new nTDSDSA object created under CN=Sites in the Configuration partition. Windows Security Event ID 4742: computer account of the attacking machine modified with GC/ and DRSUapi SPNs added. Sysmon Event ID 3: RPC connections from mimikatz.exe to DC on port 135 and dynamic RPC ports.
- Test 3DCShadow Push Phase — Trigger Replication (Mimikatz Domain Admin Session)
Expected signal: Sysmon Event ID 1: mimikatz.exe process creation with lsadump::dcshadow /push argument. Windows Security Event ID 4928 on receiving Domain Controllers: replica source naming context established, showing the rogue DC as the source. Windows Security Event ID 5136 on DCs: attribute modification on the target AD object (description attribute). Sysmon Event ID 3: outbound RPC connections to legitimate DC IP addresses on dynamic ports.
- Test 4Validate Replication Topology for Rogue DC Partners
Expected signal: Sysmon Event ID 1: repadmin.exe process creation (multiple instances for each flag). No AD modification events (read-only diagnostic). The /showconn output lists all inbound and outbound replication connections — any connection referencing an unexpected computer name or GUID identifies a rogue DC that has successfully registered in the replication topology.
References (10)
- https://attack.mitre.org/techniques/T1207/
- https://www.dcshadow.com/
- https://adsecurity.org/?page_id=1821
- https://github.com/shellster/DCSYNCMonitor
- https://adds-security.blogspot.fr/2018/02/detecter-dcshadow-impossible.html
- https://msdn.microsoft.com/en-us/library/ms677626.aspx
- https://github.com/gentilkiwi/mimikatz/wiki/module-~-lsadump
- https://learn.microsoft.com/en-us/windows-server/identity/ad-ds/manage/component-updates/directory-services-component-updates
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-deviceprocessevents-table
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-5137
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