What is the principle of least privilege?

The principle of least privilege means giving each person or tool only the access they need to do their work, and nothing more. “Access” here covers both what someone can see and what they can do. It’s one of the basic principles of information security.

Think of a part-time assistant at a cooking school. You’d give them a key to the classroom, but not to the office safe. Online tools work the same way: someone who only reads sign-ups and replies to them doesn’t need the power to change billing or remove members. Keeping access narrow means that when a mistake or a break-in happens, less is affected.

What does least privilege mean?

The US National Institute of Standards and Technology (NIST) describes least privilege as restricting the access of users, or of processes acting on their behalf, “to the minimum necessary to accomplish assigned tasks” (NIST glossary). So it applies not only to people but to anything that acts for them, such as connected apps and AI tools.

In practice, it helps to narrow access along three lines. Japan’s Information-technology Promotion Agency (IPA) frames it the same way in its guidelines on preventing insider threats.

What to narrow	What it means	Example
Who	Only the people who need access get it	Only the instructor and the office manager can see the student roster
What	People get only the permissions their work requires	They can view the roster but not export or delete it
How long	Access lasts only as long as it’s needed	Someone who helps during the busy season has access for that period only

Why does it matter for small teams?

In a small team, it’s tempting to let everyone do everything. It saves setup time, but it causes trouble in situations like these:

• Mistakes: someone who only meant to edit a page changes a setting or deletes data. The less a person can do, the less they can break by accident.
• People who leave: if accounts stay open for former staff, or for contractors who have finished their work, someone could get in later. NIST’s security controls call for disabling accounts that are no longer tied to a person, and for tying account management to the steps you take when people leave or change roles.
• Shared accounts: when several people use one account, you can’t tell who did what, and you have to change the password every time someone leaves.
• Account takeover: if an account is taken over through phishing or other means, the attacker can only do what that account is allowed to do. If an admin account is taken over, the damage can spread across the whole organization.

What is a role?

A role is a named set of permissions that are commonly used together. Instead of choosing permissions one by one for each person, you assign a role such as “viewer,” “editor,” or “admin.” This approach is called role-based access control (RBAC).

Many work tools offer roles like these. Names and details vary, so check each service’s documentation.

Common role	Example of what it can do	Good fit for
Viewer	View data only	People who check numbers, or advisers you consult
Editor or member	Create and change data	People doing the day-to-day work
Admin	Invite members, change roles, manage billing and connected apps	People who run the organization
Owner	Everything an admin can do, plus things like deleting the organization	The person responsible for the business

With roles, you don’t have to set up each new person from scratch, and when someone’s work changes, you just switch their role. If no role fits exactly, start with a narrower one and add access as needed, rather than starting too broad.

For important actions, there’s also separation of duties: not letting one person handle every step alone. For example, if one person prepares invoices and another approves payments, a single mistake or act of fraud is less likely to slip through.

What should you do day to day?

Review members regularly

Access isn’t something you set once and forget. As your work and team change, so does the access people need. Set a regular time to go through your member list and roles and ask, “Does this person still need this?” For example, check whether someone who helped only before a course launch still has an admin role. IPA suggests reviewing everyone’s access at once when staff assignments change, and NIST calls for reviewing assigned privileges periodically and removing those that are no longer needed.

Remove access promptly when someone leaves

Remove accounts for people who leave, and for contractors whose work has ended, as soon as you can. Adding “remove accounts and access” to the steps you follow when someone leaves makes it hard to forget. If the person knew a shared password, change that password too.

Limit who uses admin access, and when

Give admin access only to the people who need it. The more an account can do, the more harm a takeover can cause, so don’t share admin accounts, and protect them with passkeys or two-factor authentication. The same idea applies on your own computer: use a standard user account day to day, and use administrator rights only when you install software.

Scope API keys and connected apps

API keys and connected apps carry permissions too.

• If reading data is enough, grant read-only access.
• Create a separate API key for each purpose, and revoke keys you no longer use.
• When you connect an app, read the screen that lists what it’s asking to access, and check that nothing beyond the job is included.

“What is an API?” covers API keys, and “What is OAuth?” explains how permission works when you connect apps.

Does it apply to AI tools?

Yes. When you let an AI tool use tools of its own, such as sending emails or editing data, narrow its permissions just as you would for a person.

• For tasks that only read, give read-only access.
• Don’t let it go beyond the permissions of the person using it. Anything that person can’t do, the AI shouldn’t be able to do for them.
• Have a person review and approve anything that can’t be undone.

Giving an AI tool more access than it needs means that a wrong judgment, or instructions hidden in text it reads (prompt injection), could lead to actions nobody intended. “What is an AI agent?” goes into more detail.

Summary

• Least privilege means giving people and tools only the access their work needs, for only as long as they need it.
• Even in a small team, it limits the damage from mistakes, leftover accounts, shared accounts, and account takeovers.
• Roles make it easy to assign access, and to change it when someone’s work changes.
• Make a habit of reviewing members, removing access promptly when people leave, and scoping API keys, connected apps, and AI tools.