If a computer network were a human body, Active Directory would be the brain — storing every identity, every permission, every policy that governs how users and machines interact.
What AD provides:
- Authentication: Kerberos-based identity verification for every domain-joined device
- Authorization: Group-based access control across file shares, applications, and services
- Group Policy: Centralized configuration management for thousands of machines
- DNS integration: AD-integrated DNS zones replicate automatically with directory data
The security reality: Active Directory is the #1 target in enterprise breaches. If an attacker compromises AD, they own the entire environment. Common attack vectors include:
- Kerberoasting — extracting service account hashes for offline cracking
- Pass-the-Hash / Pass-the-Ticket — lateral movement without knowing plaintext passwords
- DCSync — impersonating a domain controller to replicate all password hashes
- Golden Ticket — forging Kerberos tickets with a compromised KRBTGT hash
Modern stance: With the rise of Entra ID (Azure AD), hybrid identity is the reality. But on-premises AD isn't going away — it's the foundation that cloud identity extends, not replaces. Protect it accordingly: tier your admin accounts, monitor replication, enable audit logging, and assume breach.