What is the principle of least privilege and how do you manage user access?

Least privilege means every user, account, and process gets the minimum access needed to do its job, and no more. It limits both accidental damage and the blast radius of a compromised account.

How to implement it:

• Role-based access control. Define roles matching job functions, assign permissions to roles, and users to roles. Never assign permissions to individuals — it becomes unmanageable and unauditable within months.
• Separate administrative accounts. Administrators get a normal account for daily work and a separate privileged account used only for administrative tasks. Browsing email as a domain administrator is how domains fall.
• Just-in-time elevation. Privileged access granted temporarily and automatically revoked, rather than standing rights.
• Service accounts with only the specific rights required, non-interactive logon, and managed or rotated credentials.

The lifecycle is where this usually fails:

• Joiners — provisioned from a role template, not by copying an existing user's access. Copying is how permissions accumulate across an organisation.
• Movers — old access removed when someone changes role. Privilege creep from people who have moved teams three times is a real and widespread risk.
• Leavers — disabled immediately, ideally automatically from the HR system.
• Periodic access reviews where managers confirm their team's access is still appropriate.