Kerberos protects critical systems by authenticating identities and granting access tokens. But in most environments, its biggest weakness isn’t the protocol—it’s the way privileges are handed out. Too many accounts have far more rights than they need. One misused service ticket or over-privileged account can open the door to privilege escalation, domain compromise, and full control of an environment.
The principle of least privilege is the antidote. Applied to Kerberos, it means every account—human or machine—should have only the exact permissions required to perform its tasks, nothing more. Service accounts should not hold admin rights unless absolutely necessary. High-value targets like domain admins should be rare, closely monitored, and never used for routine operations.
Kerberos tickets must be scoped tightly. Limit what each ticket can do by configuring Service Principal Names (SPNs) to fit the job, restricting delegation, and disabling unconstrained delegation entirely. Monitor for tickets with extended lifetimes or unusual service access. Rotate passwords for service accounts frequently. Enforce strict policies for ticket-requesting behavior and tie them to continuous monitoring.
Auditing matters. Kerberos events tell the story before a breach happens—failed logon spikes, unexpected ticket requests, or new SPNs appearing without change control are early alarm bells. Automate review of these logs and make privilege abuse detection a daily routine, not an afterthought.