Active Directory is the backbone of identity and access management in most enterprise environments — and one of the most frequently targeted systems in cyberattacks. Compromising AD means compromising everything: every user account, every server, every resource on the network.
This guide covers the most critical AD hardening steps based on real-world enterprise experience managing environments with 4,000+ users and 5,000+ endpoints.
Why Active Directory Is a Prime Target
AD controls authentication and authorisation across the network. Once an attacker gains Domain Admin — the most privileged role in AD — they can move to any system, exfiltrate data, deploy ransomware, or establish persistent access that survives reboots and reimaging.
The most dangerous AD attack techniques include:
- Pass-the-Hash: Stealing NTLM hashes to authenticate without knowing the actual password
- Kerberoasting: Extracting and cracking service account tickets offline
- DCSync: Replicating domain credentials from the Domain Controller as if you were a legitimate DC
- Attack Path Abuse: Exploiting group memberships and ACL misconfigurations to escalate privileges
1. Enforce Least Privilege Across Every Account
Domain Admins should be a small, tightly controlled group — ideally fewer than five accounts. Enterprise Admins should be empty except when absolutely required for forest-level changes.
Implement a tiered administration model:
- Tier 0: Domain Controllers and AD infrastructure only
- Tier 1: Servers and applications
- Tier 2: Workstations and end-user devices
Administrators must use separate accounts for each tier. A Tier 2 admin account must never log into a Domain Controller.
2. Protect Privileged Accounts
Never use privileged accounts for day-to-day tasks like email or browsing. Create dedicated admin accounts used exclusively for administrative functions.
Enable the Protected Users security group for all privileged accounts. Members cannot authenticate via NTLM, cannot use weak Kerberos encryption, and are not delegated by default — significantly raising the bar for credential theft.
3. Harden Service Accounts
Service accounts are high-value targets — they often have elevated privileges and weak, rarely-rotated passwords. Audit every service account:
- Remove unused service accounts immediately
- Ensure service accounts have only the permissions they need
- Use Group Managed Service Accounts (gMSA) where possible — passwords are automatically rotated and managed by AD
- Set Service Principal Names (SPNs) only on accounts that require them to reduce Kerberoasting exposure
4. Enable Comprehensive Audit Logging
Without proper logging, you cannot detect or investigate attacks. Enable these audit policies via Group Policy:
- Account Logon Events — success and failure
- Account Management — creation, deletion, group changes
- Directory Service Access
- Privilege Use
- Policy Change
Forward logs to a centralised SIEM. Reviewing logs only on the Domain Controller is insufficient — a compromised DC can have its logs tampered.
5. Enforce Strong Authentication
Configure a strong password policy via Group Policy or Fine-Grained Password Policies:
- Minimum 14+ characters for standard users, 20+ for admin accounts
- Enable complexity requirements
- Account lockout after 5 failed attempts, 15-minute lockout window
- Disable NTLM authentication where possible — enforce Kerberos
For all privileged access, enforce Multi-Factor Authentication at the authentication layer.
6. Secure Domain Controllers
DCs are your most critical assets. Apply these controls specifically:
- Allow only authorised admins to log in interactively
- Install no unnecessary software on DCs
- Enable Windows Defender Credential Guard to protect against Pass-the-Hash
- Patch DCs within 24 hours of critical security updates
- Place DCs on a dedicated network segment with strict firewall rules
7. Use BloodHound to Find Your Own Attack Paths
BloodHound maps privilege escalation paths in Active Directory — originally built for attackers, now an essential defensive tool. Run it against your own environment to find attack paths before an attacker does.
Common findings: accounts with unexpected Domain Admin membership, Kerberoastable accounts with high privileges, and ACL-based escalation paths invisible in standard AD tools.
Monitoring Is Not Optional
Hardening is not a one-time exercise. AD changes constantly — new accounts, group membership changes, new systems joining the domain. Monitor continuously for:
- New Domain Admin accounts
- Changes to privileged groups
- Unexpected logons to Domain Controllers
- Failed authentication spikes indicating brute force
- Changes to Group Policy Objects
Related reading
- Kerberoasting 2026 — practitioner playbook
- Network pentest — internal vs external
- VAPT services in India — buyer’s guide
- Web app pentest checklist — OWASP 2026
- VAPT scoping worksheet — free download
Want an expert review of your Active Directory security posture — including hands-on assessment of your configuration, privilege structure, and monitoring coverage? Get in touch with RingSafe. Real enterprise AD experience applied to your environment.