Enumerate AWS Public Resources

Public resources like EBS and RDS snapshots or SSM Documents can lead to data and credential leaks.

Dangers of Public Resources

• Many AWS resources can become public whether intentionally or not and these resources may contain sensitive data and/or credentials that may lead to a compromised environment

• There are legitimate use cases for exposing resources publicly (such as providing customers with easy access) but due diligence should be performed to ensure sensitive data and credentials are not contained in these resources

---

S3 Buckets

• Since all S3 buckets have a unique URL, they can automatically be discovered

• cloudenumworks by brute-forcing bucket names and informing if the bucket is real or not based on HTTP status codes. If a bucket is discovered, it attempts to list its contents s3:ListBucket

Discover S3 Buckets

# python3 ./cloud_enum.py -k tylerexposedbucket234 --disable-gcp --disable-azure

[+] Checking for S3 buckets
  OPEN S3 BUCKET: http://tylerexposedbucket234.s3.amazonaws.com/
      FILES:
      ->http://tylerexposedbucket234.s3.amazonaws.com/tylerexposedbucket234
      ->http://tylerexposedbucket234.s3.amazonaws.com/dogs.txt
      ->http://tylerexposedbucket234.s3.amazonaws.com/secrets.txt
  Protected S3 Bucket: http://tyler.s3.amazonaws.com/
  Protected S3 Bucket: http://tyler1.s3.amazonaws.com/
  Protected S3 Bucket: http://tyler-1.s3.amazonaws.com/
  Protected S3 Bucket: http://tyler2.s3.amazonaws.com/

---

EBS Snapshots

• EBS Snapshots are backups of EC2 instances

• dsnap is a useful tool for downloading snapshots for local inspection otherwise you can create an EC2 in your AWS account with the snapshot

Find All Public Snapshots

aws ec2 describe-snapshots --restorable-by-user-ids all

Find Public Snapshots by Owner

aws ec2 describe-snapshots --owner-ids 222222222222 --restorable-by-user-ids all

Bash

#!/bin/bash

# Description: Finds all public ebs snapshots in all regions for a given aws account

# account to check
account='111111111111'

# needed to correctly parse regions
IFS=$'\n'

echo "Checking all regions in AWS account $account"

# get all available aws regions
regions=$(aws ec2 describe-regions --region us-east-1 | jq -r '.Regions[].RegionName')

# iterate through regions
for region in $regions; do
    # check for public snapshots
    echo "Checking for Public EBS snapshots in region: $region"
    
    # check for snapshots in region
    aws ec2 describe-snapshots --owner-ids $account --restorable-by-user-ids all --region "$region" | jq -r '.Snapshots[]'
done

# reset IFS
unset IFS

---

RDS Snapshots

• RDS Snapshots are backups of RDS Databases

Find All Public Snapshots

aws rds describe-db-snapshots --include-public

Find Public Snapshots by Owner

export account='111111111111'

aws rds describe-db-snapshots --include-public | jq -r --arg aws_account "$account" '.DBSnapshots[] | select(.DBSnapshotIdentifier | contains($aws_account))'

Find Your Public Snapshots

aws rds describe-db-snapshots --snapshot-type Public

Bash

#!/bin/bash

# Description: Finds all public rds snapshots in all regions for a given aws account

# account to check
account='111111111111'

# needed to correctly parse regions
IFS=$'\n'

echo "Checking all regions in AWS account $account"

# get all available aws regions
regions=$(aws ec2 describe-regions --region us-east-1 | jq -r '.Regions[].RegionName')

# iterate through regions
for region in $regions; do
    # check for public snapshots
    echo "Checking for Public RDS snapshots in region: $region"
    
    # check for snapshots in region
    aws rds describe-db-snapshots --include-public --region $region | jq -r --arg aws_account "$account" '.DBSnapshots[] | select(.DBSnapshotIdentifier | contains($aws_account))'
done

# reset IFS
unset IFS

---

SSM Documents

• SSM Documents allow for running commands and automation

• These may contain sensitive information

Find Public Documents

#/bin/bash

# Variables
RED="\033[31m"
RESET="\033[0m"

my_ssm_docs=$(aws ssm list-documents | jq -r '.DocumentIdentifiers[] | select(.Owner | contains("111111111111")) | (.Name)')

for doc in $(echo $my_ssm_docs); do
    status=$(aws ssm describe-document-permission --name $doc --permission-type Share | jq -r '.AccountIds[]')

    if [ "$status" != "all" ]; then
        echo "The $doc is not public."
    else
        echo "${RED}The $doc is PUBLIC.${RESET}"
    fi
done

Check Document Contents

 aws ssm get-document --name <documentName> | jq -r '.Content'