Inspired by a conversation with Instacart's @nickelser on HackerOne, I've optimised and published Sandcastle – a Python script for AWS S3 bucket enumeration, formerly known as bucketCrawler.
The script takes a target's name as the stem argument (e.g.
shopify) and iterates through a file of bucket name permutations, such as the ones below:
-training -bucket -dev -attachments -photos -elasticsearch [...]
Here's how to get started:
- Clone this repo (PyPi distribution temporarily disabled).
sandcastle.pywith a target name and input file (grab an example from this repo)
- Matching bucket permutations will be identified, and read permissions tested.
usage: sandcastle.py [-h] -t targetStem [-f inputFile] arguments: -h, --help show this help message and exit -t targetStem, --target targetStem Select a target stem name (e.g. 'shopify') -f inputFile, --file inputFile Select a bucket permutation file (default: bucket- names.txt)
____ __ __ __ / __/__ ____ ___/ /______ ____ / /_/ /__ _\ \/ _ `/ _ \/ _ / __/ _ `(_-</ __/ / -_) /___/\_,_/_//_/\_,_/\__/\_,_/___/\__/_/\__/ S3 bucket enumeration // release v1.2.4 // ysx [*] Commencing enumeration of 'shopify', reading 138 lines from 'bucket-names.txt'. [+] Checking potential match: shopify-content --> 403 An error occurred (AccessDenied) when calling the ListObjects operation: Access Denied
Status codes and testing
|404||Bucket Not Found||Not a target for analysis (hidden by default)|
|403||Access Denied||Potential target for analysis via the CLI|
|200||Publicly Accessible||Potential target for analysis via the CLI|
AWS CLI commands
Here's a quick reference of some useful AWS CLI commands:
- List Files:
aws s3 ls s3://bucket-name
- Download Files:
aws s3 cp s3://bucket-name/<file> <destination>
- Upload Files:
aws s3 cp/mv test-file.txt s3://bucket-name
- Remove Files:
aws s3 rm s3://bucket-name/test-file.txt
What is S3?
From the Amazon documentation, Working with Amazon S3 Buckets:
Amazon S3 [Simple Storage Service] is cloud storage for the Internet. To upload your data (photos, videos, documents etc.), you first create a bucket in one of the AWS Regions. You can then upload any number of objects to the bucket.
In terms of implementation, buckets and objects are resources, and Amazon S3 provides APIs for you to manage them.
- This is my first public security project. Sandcastle is published under the MIT License.
- Usage acknowlegements:
- Castle (icon) by Andrew Doane from the Noun Project
- Nixie One (logo typeface) free by Jovanny Lemonad