Active Directory Hardening Checklist for MSPs in 2026
Active Directory remains the primary target in most enterprise attacks. Use this hardening checklist to secure your clients AD environments today.
Despite the cloud migration trend, Active Directory remains the backbone of identity management for the vast majority of organizations. It's also the number one target in post-exploitation scenarios — once an attacker has a foothold, their next move is almost always to escalate privileges within AD. For MSPs managing dozens of client AD environments, a standardized hardening baseline is essential. You can't afford to configure each environment ad-hoc and hope you didn't miss anything.
Tier Model and Privileged Access
Implement the Microsoft tier model to segment administrative access. Tier 0 (domain controllers and AD infrastructure) should only be accessible from dedicated Privileged Access Workstations. Tier 1 (member servers) and Tier 2 (workstations) each get their own admin accounts that cannot be used on higher tiers. This prevents a compromised workstation admin credential from being used to attack domain controllers. Disable the built-in Administrator account and create unique named admin accounts with strong passwords. Deploy Local Administrator Password Solution (LAPS) to ensure every machine has a unique local admin password that rotates automatically. Remove all unnecessary members from Domain Admins — this group should contain the absolute minimum number of accounts needed.
Detection and Monitoring
Enable advanced audit policies across all domain controllers: log successful and failed logon events, privilege use, directory service access, and security group modifications. Forward these logs to your SIEM and create alerts for high-risk events: new members added to Domain Admins, DCSync operations, Kerberoasting attempts, pass-the-hash patterns, and golden ticket indicators. Deploy Microsoft Defender for Identity or an equivalent solution that can detect AD-specific attack techniques in real time. Regularly run tools like PingCastle or Purple Knight to assess your AD security posture against known attack vectors and misconfigurations. Schedule quarterly AD security reviews for every client — don't wait for an incident to discover that someone added a service account to Domain Admins six months ago.