Cis AWS Compute 5.9

5.9 Ensure that your Lightsail buckets are not publicly accessible (Manual)

Description

You can make all objects private, public (read-only) or private while making individual objects public (read-only). By default when creating a bucket the permissions are set to "All objects are private".

Rationale

When the Bucket access permissions are set to All objects are public (read-only) - All objects in the bucket are readable by anyone on the internet through the URL of the bucket.

Impact

N/A

Audit Procedure

Using AWS Console

1. Login to AWS Console using https://console.aws.amazon.com
2. Click All services, click Lightsail under Compute.
3. This will open up the Lightsail console.
4. Select Storage.
5. All Lightsail buckets are listed here.
6. Underneath the bucket name and size there are 3 possible statements:

All objects are private
All objects are public (read-Only)
Individual objects can be public

7. If any buckets are set to All objects are public (read-Only) and or 'Individual objects can be public' refer to the remediation below.

Using AWS CLI

1. Run aws lightsail get-buckets

aws lightsail get-buckets

This command will provide a list of Buckets tied to Lightsail.

2. Review the accessRules, getobject and allowPublicOverrides.

"accessRules": {
    "getObject": "private",
    "allowPublicOverrides": false
}

4. If it reads "getObject": "public" or "allowPublicOverrides": true please make note "name" of the bucket also listed in the output.
5. Then refer to the remediation below.

Expected Result

All Lightsail buckets should have access rules set to "getObject": "private" and "allowPublicOverrides": false, meaning all objects are private.

Remediation

Using AWS Console

1. Login to AWS Console using https://console.aws.amazon.com
2. Click All services, click Lightsail under Compute.
3. This will open up the Lightsail console.
4. Select Storage.
5. All Lightsail buckets are listed here.
6. Click on the bucket name that has All objects are public (read-Only) listed.
7. Click on Permissions
8. Click on Change permissions
9. Select All objects are private
10. Click Save
11. Repeat for any other Buckets within Lightsail that are set with All objects are public (read-Only) and/or Individual objects can be made public and read only

Using AWS CLI

1. Run aws lightsail update-bucket

aws lightsail update-bucket --bucket-name <name from list in audit> --access-rules getObject="private",allowPublicOverrides=false

2. The confirmation that the change was made will print out after running that command.
3. Repeat for any other buckets listed in the audit.

Default Value

By default when creating a bucket the permissions are set to "All objects are private".

References

1. https://lightsail.aws.amazon.com/ls/docs/en_us/articles/amazon-lightsail-understanding-bucket-permissions

CIS Controls

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Level 1 | Manual