bucketkicker

bucketkicker is a tool to quickly enumerate AWS S3 buckets verify whether or not they exist and to look for loot. It's similar to a subdomain bruteforcer but is made specifically for S3 buckets and also has some extra features that allow you to grep for delicious files as well as download interesting files if you're not afraid to quickly fill up your hard drive.

@CraigHays

Pre-Requisites

Non-Standard Python Libraries:

xmltodict
requests
argparse

Created with Python 3.6

Install with virtualenv

source venv/bin/activate
pip install -r requirements.txt

General

This is a tool that enumerates Amazon S3 buckets to confirm whether or not they exist, are open to the webm and can also look for interesting files.

I have included a wordlist generater which I will improve to add more rules as time goes by.

https://github.com/danielmiessler/SecLists will have all the word lists you need. If you are targeting a specific company, you will likely want to use massdns to ennumerate a list of DNS subdomains to feed into this.

Original wording around grepping stuff from jordanpotti

As far as word lists for grepping interesting files, that is completely up to you. The one I provided has some basics and yes, those word lists are based on files that I personally have found with this tool.

Using the download feature might fill your hard drive up, you can provide a max file size for each download at the command line when you run the tool. Keep in mind that it is in bytes.

I honestly don't know if Amazon rate limits this, I am guessing they do to some point but I haven't gotten around to figuring out what that limit is. By default there are two threads for checking buckets and two buckets for downloading.

After building this tool, I did find an interesting article from Rapid7 regarding this research.

Usage:

usage: bucketkicker.py [-h] [-D] [-t THREADS] -l HOSTLIST [-g GREPWORDS] [-m MAXSIZE]

optional arguments:
  -b            Write list of open buckets to openbuckets.txt only - don't look at contents - fastest way to ennumerate buckets
  -h, --help    show this help message and exit
  -D            Download files. This requires significant diskspace
  -d            If set to 1 or True, create directories for each host w/ results
  -t THREADS    number of threads
  -l HOSTLIST
  -g GREPWORDS  Provide a wordlist to grep for
  -m MAXSIZE    Maximum file size to download.

 python3 bucketkicker.py -d False -l <wordlistfile> -g grepfile.txt -b

Generating random wordlists via crunch

kali > crunch <min> <max> -f charset s3 -o <output filename>

stripping out invalid line starts and ends

sed '/^./ d' | sed "/.$/d" | sed '/^-/ d' | sed "/-$/d"

Naming rules

S3 URLs use the format http://bucketname.s3.amazonaws.com . If we replace bucketname with random strings that meet the following rules it is possible to see if buckets exist. Feed this tool with a wordlist of your choice and you're good to go.

Rules from https://docs.aws.amazon.com/AmazonS3/latest/dev/BucketRestrictions.html

Bucket names must be at least 3 and no more than 63 characters long.
Bucket names must be a series of one or more labels. Adjacent labels are separated by a single period (.). Bucket names can contain lowercase letters, numbers, and hyphens. Each label must start and end with a lowercase letter or a number.
Bucket names must not be formatted as an IP address (for example, 192.168.5.4).
When using virtual hosted–style buckets with SSL, the SSL wildcard certificate only matches buckets that do not contain periods. To work around this, use HTTP or write your own certificate verification logic. We recommend that you do not use periods (".") in bucket names.