Securing Active Directory (AD) is crucial for ensuring the integrity and confidentiality of the data stored within it. A compromised AD can lead to unauthorized access, privilege escalation, and even full network compromise. Below are best practices and strategies for securing Active Directory:
1. Use Strong Password Policies
- Password Length and Complexity: Enforce a strong password policy requiring long, complex passwords (e.g., a mix of uppercase, lowercase, numbers, and special characters).
- Password Expiration: Implement regular password changes (every 60-90 days), but avoid forcing users to change passwords too frequently.
- Account Lockout Policy: Configure account lockout policies after a set number of failed login attempts (e.g., 5 attempts) to prevent brute force attacks.
Set-ADDefaultDomainPasswordPolicy -MaxPasswordAge 30
Set-ADDefaultDomainPasswordPolicy -MinPasswordLength 12
2. Implement Multi-Factor Authentication (MFA)
- Enable MFA for all users, especially privileged accounts, to add an additional layer of security.
- Use solutions like Azure AD MFA or third-party tools to implement MFA for AD accounts.
3. Use Role-Based Access Control (RBAC)
- Implement the Principle of Least Privilege (PoLP) by assigning only the minimum permissions necessary for users and groups to perform their job functions.
- Create and use security groups to manage permissions and rights rather than assigning permissions to individual users.
4. Monitor and Audit Active Directory
- Enable Auditing: Turn on auditing to track changes and access events in AD. Monitor who is modifying accounts, creating groups, or changing permissions.
- Review Logs Regularly: Use tools like Event Viewer or SIEM solutions (e.g., Splunk, SolarWinds) to review the security logs.
- Set up alerts for critical events, such as account lockouts, privilege escalation, or changes to security groups.
AuditPol /set /subcategory:"Logon/Logoff" /success:enable /failure:enable
5. Protect Domain Controllers
- Physical Security: Ensure that domain controllers are physically secured.
- Isolation: Place domain controllers in a protected subnet, isolated from non-essential network traffic, and apply firewall rules.
- Secure Administrative Access: Use Privileged Access Workstations (PAWs) for administrators to reduce exposure to malware and phishing attacks.
- Group Policy: Limit administrative permissions on domain controllers and configure Group Policy to restrict the use of administrative tools.
6. Implement Group Policy Best Practices
- Enforce Password Policies: Configure Group Policy to enforce password policies, lockout policies, and user rights assignments.
- Restrict Local Administrator Groups: Ensure that local administrator accounts on workstations and servers are managed centrally via Group Policy and that there are no unnecessary members in the local Administrator group.
Set-ADUser -Identity "Administrator" -Enabled $false
7. Control and Audit Privileged Access
- Use Just-In-Time (JIT) Privilege Elevation: Use Privileged Access Management (PAM) or tools like Microsoft’s LAPS (Local Administrator Password Solution) to temporarily elevate user privileges when necessary and automatically manage passwords for privileged accounts.
- Restrict Administrative Group Membership: Limit membership in high-privilege groups (e.g., Domain Admins, Enterprise Admins) to only those who absolutely need them. Regularly review and audit group memberships.
Get-ADGroupMember -Identity "Domain Admins" | Select Name
8. Limit the Use of Administrative Accounts
- Create dedicated administrative accounts for managing Active Directory (e.g., Domain Admins), separate from regular user accounts. Never use administrative accounts for daily tasks or browsing the web.
- Disable or remove inactive admin accounts promptly.
9. Use Secure DNS and LDAP Connections
- Enforce the use of LDAP over SSL (LDAPS) for secure directory queries and ensure DNS is secured to prevent DNS poisoning attacks.
- Disable unused or non-secure ports and services.
10. Implement Network Segmentation
- Isolate the Active Directory infrastructure (including domain controllers) from the rest of the network to minimize exposure to attacks. Implement strict firewall rules to control traffic between segments.
- Use Network Access Control (NAC) to ensure that only trusted devices can access the AD network.
11. Apply Security Patches Regularly
- Keep all domain controllers, servers, and workstations fully patched with the latest security updates. Regularly review and apply patches to avoid vulnerabilities.
- Use Windows Server Update Services (WSUS) or similar patch management solutions to automate this process.
12. Disable SMBv1 and Unnecessary Services
- Disable SMBv1 and any other obsolete or insecure services to reduce the attack surface.
- Configure Windows Firewall and other security settings to block unneeded services from running.
Set-SmbServerConfiguration -EnableSMB1Protocol $false
13. Implement Security Baselines
- Use security baselines such as Microsoft Security Baselines or the CIS (Center for Internet Security) Active Directory Benchmark to secure your environment.
- Periodically review and apply these baselines to ensure compliance.
14. Use Active Directory Recycle Bin
- Enable the Active Directory Recycle Bin to recover accidentally deleted objects, such as users or groups, without requiring authoritative restores.
- The AD Recycle Bin should be enabled for all domains.
Enable-ADOptionalFeature -Identity 'Recycle Bin Feature' -Scope ForestOrConfigurationSet -Target 'domain.com'
15. Secure Service Accounts
- Managed Service Accounts (MSAs) should be used for services that need AD authentication. MSAs automatically manage passwords, ensuring that they are complex and rotated regularly.
- Use Group Managed Service Accounts (gMSAs) for services running on multiple servers.
16. Backup and Disaster Recovery Planning
- Regularly back up Active Directory and test your disaster recovery process. Use Windows Server Backup or other backup tools to create snapshots of domain controllers.
- Consider using System State Backup to back up essential AD data.
17. Control Trust Relationships
- Limit the number of domain trusts to only those necessary. Review and periodically audit external and forest trusts.
- Consider one-way trust relationships to restrict unnecessary permissions.
18. Monitor for Suspicious Activities
- Monitor event logs for unusual or suspicious activity, including:
- Changes to AD schema or group memberships.
- Use of high-level admin accounts.
- Use of malicious PowerShell commands or WMI (Windows Management Instrumentation) queries.
- Set up alerts for critical events in tools like Windows Event Viewer, Sysmon, or SIEM solutions.
19. Implement Least Privilege for Delegation
- Delegate administrative permissions based on role and necessity. Use Active Directory Delegation of Control Wizard to assign permissions at the OU level.
- Ensure that no one has excessive rights over organizational units (OUs).
20. Review AD Permissions and Group Membership Regularly
- Perform regular audits of all AD permissions and group memberships. Use scripts or tools to review and ensure that users only have the minimum necessary privileges.
- Regularly clean up and remove obsolete users, groups, and computers.
Get-ADGroupMember -Identity "Domain Admins" | Select-Object Name
Securing Active Directory is an ongoing process that requires attention to detail and regular reviews. Implementing best practices such as strong password policies, MFA, limited administrative privileges, encryption, regular auditing, and proper backup strategies will significantly reduce the risk of a security breach and protect your organization’s infrastructure.