Lion Cipher Lab
Keep an S3 bucket private (AWS Free Tier)
- Cloud Security
- Beginner
- ~40 min
- Free · no account required
Why it matters
When people picture a cloud breach they imagine a break-in, but the most common way data leaks out of the cloud is far more boring: someone puts files in object storage and the storage is left open to the whole internet. Amazon S3 is where most AWS users keep their first real data, and the classic "open S3 bucket" headline is almost always a misconfiguration, not an attack — a bucket that anyone with the link could read because a setting was flipped or never checked. AWS's own guidance is blunt about it: unless you explicitly need anyone on the internet to read or write your bucket, make sure…
What you'll learn
- Amazon S3 basics
- S3 Block Public Access
- bucket policies and ACLs
- the meaning of a "public" bucket
- least-privilege storage
- cleaning up cloud resources
Steps in this lab
- The leak that keeps happening: the open bucket
- Create a bucket on your own account
- Meet the master switch: Block Public Access, on by default
- Put a file in it
- Prove it is NOT reachable from the public internet
- Look under the hood: ACLs, the bucket policy, and what "public" means
- How buckets get exposed by accident — and then clean up
- What you just learned — and why it sticks