The Principle of Least Privilege

The principle of least privilege is one of the most important concepts in information security. In AWS, it means granting each identity — whether a user, role, or service — only the permissions it needs to perform its specific task, and nothing more.

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What is Least Privilege?

Least privilege states that every identity should have the minimum set of permissions required to do its job. No more, no less.

This is not about making things difficult — it is about reducing risk. If a user only needs to read objects from one S3 bucket, giving them full administrator access creates unnecessary exposure. If their credentials are compromised, the attacker inherits all of those excessive permissions.

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Why Least Privilege Matters

Reduce Blast Radius

If a set of credentials is compromised, the damage is limited to what those credentials can do. Least privilege minimises the blast radius.

Scenario	Permissions	Blast Radius
Developer with admin access is compromised	Full account access	Entire AWS account
Developer with S3-read-only is compromised	Can read one S3 bucket	One bucket's data