HardenAD is an open-source PowerShell security framework created by Loic Veirman to automate Microsoft Active Directory hardening. It enforces tier administrative delegation, configures Group Policy security controls, restricts privileged service accounts, and eliminates attack paths exploited during lateral movement and privilege escalation.
Understanding Active Directory Attack Vectors and Risks
Microsoft Active Directory (AD) serves as the central identity and access management backbone for enterprise networks. Because AD controls authentication and access permissions across domains, attackers frequently target AD architectures during advanced intrusions. Common identity attack techniques include:
- Kerberoasting: Requesting Kerberos service tickets for accounts with Service Principal Names (SPNs) and cracking the ticket hashes offline.
- Pass-the-Hash and Pass-the-Ticket: Harvesting cached NTLM hashes or Kerberos tickets from compromised endpoints to traverse systems without passwords.
- Privilege Escalation via Misconfigured ACLs: Exploiting excessive Access Control Lists (ACLs) or unconstrained delegations to seize Domain Admin privileges.
- LLMNR and NetBIOS Spoofing: Poisoning unauthenticated name resolution protocols on local networks to capture user credentials.
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Core Capabilities and Automated Features of HardenAD
HardenAD automates the implementation of security configurations that would otherwise require weeks of manual Group Policy scripting and directory restructuring. Key automated capabilities include:
- Legacy Protocol Deactivation: Disables insecure legacy protocols including SMBv1, LLMNR, NBT-NS, and RC4 Kerberos encryption across domain endpoints.
- Privileged Account Protection: Implements Protected Users security group policies, enforces Kerberos FAST armoring, and blocks credential caching on workstations.
- Service Account Hardening: Audits SPNs, disables unconstrained delegation, and promotes migration to Group Managed Service Accounts (gMSAs).
- Group Policy Object (GPO) Deployment: Automatically generates and links security GPOs configured with Microsoft Security Compliance Toolkit baselines.
Implementing the Tier Administrative Delegation Model
A cornerstone of HardenAD is automating the Tier Administrative Model (formerly known as ESAE or Red Forest). The framework separates administrative privileges into three distinct tiers to prevent credential theft across security boundaries:
- Tier 0 (Control Plane): Domain Controllers, PKI certification authorities, and identity synchronization systems. Tier 0 administrators are strictly prohibited from logging into lower-tier systems.
- Tier 1 (Enterprise Servers): Member servers, enterprise applications, database clusters, and cloud integration nodes.
- Tier 2 (User Workstations & Devices): End-user computers, laptops, and peripheral client devices where malware infections commonly originate.
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HardenAD Execution Workflow and Architecture
| Security Domain | Hardening Action Automated by HardenAD | Attack Vector Mitigated |
|---|---|---|
| Authentication Protocols | Enforces Kerberos AES, disables NTLMv1 and LLMNR | Credential relay, hash cracking, and protocol spoofing |
| Administrative Tiering | Creates Tier 0/1/2 OUs, GPOs, and logon restriction policies | Lateral movement and domain takeover via LSASS dumping |
| Service Accounts | Restricts delegation rights and audits SPN configurations | Kerberoasting and unconstrained delegation abuse |
| Endpoint Defenses | Enforces Local Administrator Password Solution (LAPS) | Local credential reuse and workstation hop-through |
Operational Recommendations for AD Hardening
To deploy HardenAD safely in production enterprise environments, security teams should adhere to structured deployment phases:
- Test in a Dedicated Staging Forest: Execute the PowerShell task sequences within an isolated test lab to evaluate application compatibility before domain-wide rollout.
- Enable Audit Mode First: Apply GPO restrictions in audit mode to monitor event logs for authentication failures or broken legacy service connections.
- Deploy LAPS Universally: Ensure Windows LAPS or Microsoft LAPS is configured across all domain endpoints to randomize local administrator passwords.
- Continuous Monitoring: Complement hardening automation with ongoing directory audits using tools like BloodHound and PingCastle.