When you buy a computer and set it up for the first time, the account you create is almost always an administrator. It can install programs, change system settings, turn off protections and read other users' files. It's convenient, and indeed most people use it that way for years. The principle of least privilege suggests the opposite: every person, and every program, should have only the permissions strictly necessary for what they need to do.
Why it makes a difference
When a malicious program starts, it inherits the permissions of the user who launched it. If that user is an administrator, the program can embed itself deep in the system, disable the antivirus, create new accounts and change how the computer behaves at start-up. If the user is a standard one, many of these actions are blocked or require a password the program doesn't know.
The same goes for human error. A standard user can't accidentally delete system files or change critical settings without noticing.
It isn't absolute protection: malware can still encrypt the documents the user has access to. But it greatly reduces the scope of the damage and makes it harder for an intruder to stay in the system.
On the home or office computer
Two separate accounts
The recommended setup is simple:
- an administrator account, with a long, unique password, used only to install programs and change settings;
- a standard account for all everyday activity: email, browsing, documents.
When an administrative operation is needed from the standard account, Windows and macOS ask for the administrator's credentials. That prompt becomes a moment of attention: if it appears when you're only opening an attachment, something is wrong.
If others use the computer too
Each person should have their own standard account. Children and guests in particular should never use an account with privileges.
Don't turn off the prompts
On Windows, User Account Control shows a confirmation prompt before important changes. Turning it down to the minimum so as not to be bothered removes the very barrier that protects you.
In cloud accounts
The principle applies even more to online services, where an administrator account can manage everyone's email, company files and billing.
- Separate the admin account from the personal one: whoever manages the company email platform should have a normal work account and a distinct administrative account, used only when needed.
- Limit the number of administrators: two trusted people are almost always enough. Just one is risky, because if they lose access nobody can step in; ten are too many.
- Use roles: many platforms offer intermediate roles, such as "billing administrator" or "user manager". Assign the role that matches the task, not the all-powerful one.
- Protect administrators with the strongest method: a physical security key or passkey, not SMS.
- Plan for emergency access: a backup administrative account, with credentials stored securely and used only if the others fail.
Shared folders and documents
In small businesses it often happens that everyone can read and change everything: the shared folder holds accounts, payslips, contracts and sales material, with the same permissions for all. Apply least privilege here too:
- organise folders by area (administration, sales, technical);
- give read access to those who only need to consult and edit access only to those who must work on the files;
- for external sharing links, set an expiry date and limit access to named people instead of "anyone with the link".
Programs and services
Software, too, should have only the permissions it needs. A phone app doesn't need your contacts to show the weather; an integration connected to your cloud account shouldn't have full access to all your email if it only needs the calendar. When you connect an outside service to an account, read the permissions it requests.
Periodic review
Privileges tend to pile up: someone is given a permission for a project, the project ends, but the permission stays. At least a couple of times a year:
- list who is an administrator on computers and cloud services;
- remove privileges that are no longer needed;
- check which external shares are still active.
In short
- Least privilege gives people and programs only the permissions they need.
- Use a standard account every day and the administrator only when necessary.
- In cloud services, separate admin accounts, limit their number and use roles.
- Apply differentiated permissions to shared folders and external links too.
- Review privileges regularly: they tend to accumulate.