Active Directory Security Best Practices

Active Directory (AD) is a crucial component of enterprise IT infrastructure, managing authentication and access control. Given its importance, securing AD is essential to prevent unauthorized access and potential security breaches. Below are best practices to enhance AD security.

Implement Strong Authentication and Access Controls

• Enforce Multi-Factor Authentication (MFA): Protect privileged accounts by requiring an additional layer of authentication.
• Use Strong Password Policies: Implement complexity requirements and enforce periodic password changes.
• Limit Privileged Account Usage: Admin accounts should only be used for administrative tasks and not for everyday activities.
• Use Active directory tiering model Why You Should Use Microsoft’s Active Directory Tier Administrative Model – Petri IT Knowledgebase
• Delegation model: Use OU delegation model to limit the privilege account usage

Secure Domain Controllers (DCs)

• Restrict Physical and Network Access: Only authorized personnel should have access to DCs.
• Monitor and Limit Admin Access: Use role-based access control (RBAC) to limit unnecessary permissions.
• Patch and Update Regularly: Ensure DCs have the latest security updates and patches.
• Delete unused Trust relationships: Understand the difference between Trusted and Trusting domain and establish trust only if needed

Harden Active Directory Configurations

• Disable Unused Accounts: Regularly review and remove stale user and computer accounts.
• Enable Account Lockout Policies: Prevent brute-force attacks by limiting login attempts.
• Use Secure LDAP (LDAPS): Encrypt communication between AD and clients.

Implement Network Segmentation and Least Privilege

• Separate Admin and User Networks: Restrict admin access to only necessary systems.
• Limit Group Membership: Only assign privileged roles to essential personnel.
• Use Tiered Administrative Model: Implement a tiered model to reduce the risk of credential compromise.

Monitor and Audit AD Activity

• Enable Logging and Auditing: Track authentication attempts, privilege escalations, and access changes.
• Use SIEM Solutions: Integrate with Security Information and Event Management (SIEM) for real-time threat detection.
• Review Admin Group Memberships Regularly: Ensure that only authorized users retain access.

Protect Against Credential Theft

• Use LAPS for Local Admin Accounts: Microsoft’s Local Administrator Password Solution (LAPS) helps secure local accounts.
• Implement Credential Guard: Protect credentials from being harvested by attackers.
• Block NTLM Authentication Where Possible: Favor Kerberos authentication over NTLM.

Backup and Disaster Recovery Planning

• Regularly Backup AD Data: Ensure backups are encrypted and stored securely.
• Test Recovery Processes: Conduct periodic restoration tests to validate backup integrity.
• Maintain Offline Backups: Protect against ransomware by keeping isolated backups.

Secure Group Policies

• Restrict GPO Editing Rights: Limit Group Policy Object (GPO) modifications to authorized administrators.
• Use Read-Only Domain Controllers (RODCs): Deploy RODCs in locations with lower security measures.
• Audit GPO Changes: Regularly review policy modifications for unauthorized changes.

Reduce Attack Surface with Modern Security Tools

• Deploy Microsoft Defender for Identity (MDI): Detect suspicious activities within AD.
• Leverage Conditional Access Policies: Ensure secure authentication based on risk factors.
• Enable Just-in-Time (JIT) and Just-Enough-Administration (JEA): Minimize exposure of privileged accounts.

Conclusion

Securing Active Directory requires a multi-layered approach, combining strong authentication, regular monitoring, and proper access controls. By following these best practices, organizations can significantly reduce the risk of security breaches and ensure a resilient AD infrastructure.