Active Directory (AD) Security Checklist: Best Practices for a Secure Environment

Dan Hill
May 6
2 min read

Securing an Active Directory environment is crucial to protecting organizational data and preventing unauthorized access.

Here's a comprehensive checklist:

1. AD Configuration Best Practices

Enable Secure Default Settings: Ensure secure defaults for new installations (e.g., disable LM/NTLMv1 authentication).
Separate Administrative Accounts: Avoid using the same account for administrative tasks and everyday activities.
Implement Tiered Administration: Use a tier model to isolate privileges (e.g., Tier 0 for domain controllers).

2. Strong Password Policies

Enforce Complex Passwords: Require a mix of uppercase, lowercase, numbers, and special characters.
Use Password Expiration Policies: Set reasonable expiration times and enforce password history.
Adopt Passphrases: Encourage longer, memorable passphrases for enhanced security.

3. Privilege Management

Use Least Privilege Principle: Assign only the minimum required privileges to users and groups.
Limit Membership in Privileged Groups: Restrict accounts in Domain Admins, Enterprise Admins, and Schema Admins groups.
Monitor Privileged Access: Regularly review privileged account usage and membership.

4. Group Policy Hardening

Restrict Anonymous Access: Disable anonymous enumeration of SAM accounts and shares.
Disable Unused Services: Turn off unused AD features and roles.
Implement Logon Restrictions: Limit logon hours and set workstation restrictions for administrative accounts.

5. Multi-Factor Authentication (MFA)

Enable MFA for Privileged Accounts: Require MFA for all administrative and high-risk accounts.
Extend MFA to All Users: Gradually roll out MFA for the general user base.

6. Auditing and Logging

Enable Auditing: Monitor changes to AD objects, logon attempts, and access events.
Centralize Logs: Use a Security Information and Event Management (SIEM) system for centralized logging and analysis.
Review Logs Regularly: Investigate anomalies and failed logon attempts.

7. Patch Management

Keep Domain Controllers Updated: Regularly apply patches and updates to all AD servers.
Address Vulnerabilities Promptly: Prioritize critical updates to fix known security flaws.

8. Secure Communication Channels

Use Secure LDAP (LDAPS): Encrypt directory access with SSL/TLS.
Enforce SMB Signing: Secure communication between clients and domain controllers.
Disable Weak Encryption Protocols: Block protocols like SSL 3.0 and older versions of TLS.

9. Backup and Recovery

Regularly Backup AD: Perform frequent backups of AD databases and system state.
Test Recovery Plans: Validate that backups can be restored in case of a failure or attack.

10. Mitigating Insider Threats

Monitor Suspicious Activity: Track unusual access patterns, such as bulk modifications or account creations.
Use Just-in-Time Administration: Provide temporary administrative access for specific tasks.
Disable Inactive Accounts: Identify and deactivate accounts that are no longer in use.

11. Protect Against Malware and Ransomware

Deploy Endpoint Protection: Use antivirus and anti-malware solutions on all AD-connected devices.
Restrict PowerShell Use: Limit PowerShell access to administrators and monitor script execution.
Isolate Domain Controllers: Use firewalls and network segmentation to protect domain controllers.

12. Regular Security Assessments

Conduct Penetration Testing: Simulate attacks to identify vulnerabilities.
Perform Risk Assessments: Periodically review AD configurations against best practices.
Utilize Security Baselines: Use tools like Microsoft Security Compliance Toolkit to implement baseline policies.

By systematically applying these measures, you can significantly reduce the risk of unauthorized access and improve the resilience of your Active Directory environment.