Administrative Tier Model

Introduction to the Administrative Tier Model

The Administrative Tier Model is a security framework designed to protect privileged access within an Active Directory environment. It segregates administrative duties and accounts into distinct tiers, reducing the risk of privilege escalation and lateral movement by potential attackers.

The Three Tiers

Tier 0: Domain Controllers and Critical Assets

• Includes Domain Controllers, Active Directory Certificate Services, and other critical infrastructure
• Managed by Enterprise Admins and Domain Admins
• Highest level of privilege and strictest security controls

Tier 1: Servers and Applications

• Includes application servers, database servers, and other non-domain controller servers
• Managed by server administrators
• No ability to manage Tier 0 assets

Tier 2: Workstations and User Devices

• Includes user workstations, laptops, and other end-user devices
• Managed by helpdesk and desktop support personnel
• No ability to manage Tier 0 or Tier 1 assets

Implementing the Administrative Tier Model

1. Identify and categorize assets into appropriate tiers
2. Create separate administrative accounts for each tier
3. Implement strict access controls between tiers
4. Use Privileged Access Management (PAM) in Active Directory for Tier 0 administration
5. Implement Just-In-Time (JIT) and Just-Enough-Administration (JEA) principles
6. Regularly audit and review tier memberships and permissions

Best Practices for Tier Model Security

• Enforce Multi-Factor Authentication (MFA) for all administrative accounts
• Implement time-based restrictions on administrative access
• Use Privileged Identity Management (PIM) for just-in-time privileged access
• Regularly rotate passwords for administrative accounts
• Monitor and alert on any attempts to access higher tiers from lower tiers
• Implement strict network segmentation between tiers

Challenges and Considerations

• Initial implementation can be complex and time-consuming
• Requires changes to existing administrative processes and workflows
• May face resistance from administrators accustomed to full access
• Ongoing maintenance and auditing is crucial for effectiveness

Additional Resources

• Detailed Tier Model Implementation Guide
• Setting Up Privileged Access Workstations (PAWs)
• Just Enough Administration (JEA) Configuration