Exercise 11: Cloud Storage Data Breach via Improper Access Control

Objective:

Understand the risks associated with improperly configured access controls on cloud storage. Demonstrate how attackers can exploit weak configurations to access sensitive data and learn best practices to secure cloud storage.

Scenario:

You are assessing the cloud storage configurations for an organization. During the assessment, you identify a storage bucket configured with weak access controls, such as public read or write permissions. Your task is to demonstrate how attackers can exploit these configurations to access sensitive data and recommend mitigation strategies.

Lab Setup:

Prerequisites:

1. Access to a cloud storage platform:
   • AWS S3 or Google Cloud Storage.
2. Installed tools:
   • aws-cli (for AWS S3) or gsutil (for Google Cloud Storage).

Steps to Set Up the Lab:

Option 1: AWS S3:

Create an S3 Bucket:

Log in to the AWS Management Console and navigate to S3.

Click Create bucket and configure:

Bucket Name: pentesterworld-exposed-bucket.

Block Public Access Settings: Uncheck Block all public access.

Complete the setup.

Upload Sensitive Files:

Upload a file containing mock sensitive data, such as:

financial-records.csv: A CSV file with fake financial data.

private-keys.txt: A text file simulating private keys or credentials.

Set Improper Access Controls:

In the Permissions tab, configure:

Bucket policy:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": "*",
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::pentesterworld-exposed-bucket/*"
    }
  ]
}

This grants public read access to all objects in the bucket.

Verify Public Access:

Access the file via a public URL:

https://<bucket-name>.s3.<region>.amazonaws.com/<file-name>

Confirm that the file can be downloaded without authentication.

Option 2: Google Cloud Storage:

1. Create a Storage Bucket:
   • Log in to the Google Cloud Console and navigate to Cloud Storage.
   • Click Create Bucket and configure:
     • Bucket Name: pentesterworld-public-bucket.
     • Access Control: Set to Uniform (all objects inherit the bucket’s permissions).
2. Upload Sensitive Files:
   • Upload files with sensitive content, such as mock financial records or credentials.
3. Set Improper Permissions:
   • Make the bucket publicly accessible:
     • Under Permissions, add allUsers with the role Storage Object Viewer.
   • Verify that the bucket and its contents are publicly accessible.

Exercise: Exploiting Improper Access Controls

Objective:

Simulate an attacker accessing sensitive files due to improper access control.

List Publicly Accessible Files:

Use aws-cli (AWS S3):

aws s3 ls s3://pentesterworld-exposed-bucket/ --no-sign-request

Use gsutil (Google Cloud Storage):bashCopyEditgsutil ls gs://pentesterworld-public-bucket/

Download Sensitive Files:

AWS S3:

aws s3 cp s3://pentesterworld-exposed-bucket/financial-records.csv . --no-sign-request

Google Cloud Storage:

gsutil cp gs://pentesterworld-public-bucket/financial-records.csv .

Simulate Data Manipulation (Optional):

If the bucket allows public write access, upload a file to simulate tampering:

aws s3 cp malicious-script.sh s3://pentesterworld-exposed-bucket/ --no-sign-request

Verify the upload via the bucket’s URL.

Tools Required:

1. AWS S3 or Google Cloud Storage: For setting up the bucket.
2. aws-cli or gsutil: For interacting with cloud storage.
3. Web Browser: To verify public accessibility of the files.

Deliverables:

1. Exploit Report:
   • Evidence of accessing sensitive files via public URLs.
   • Screenshots of commands or web browser access to the files.
   • Documentation of data manipulation if public write access was enabled.
2. Recommendations for Securing Cloud Storage:
   • Best practices for configuring access controls, such as using ACLs and IAM policies.

Solution:

Identified Vulnerabilities:

Public Access: The bucket was accessible to anyone without authentication.

Weak Permissions: Public read or write permissions allowed unauthorized data access or modification.

No Monitoring: Access to the bucket was not logged or monitored.

Consequences:

Data Breach: Sensitive data, such as financial records, was exposed.

Data Manipulation: Public write permissions allowed attackers to modify or upload malicious files.

Compliance Violations: Exposing sensitive data violates regulatory requirements, such as GDPR or HIPAA.

Prevention Techniques:

Restrict Public Access:

Block public access to buckets by default.

For AWS S3, enable Block Public Access settings.

Use IAM Policies and ACLs:

Assign least privilege permissions to IAM roles and users.

Example AWS S3 bucket policy to deny public access:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Deny",
      "Principal": "*",
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::pentesterworld-exposed-bucket/*"
    }
  ]
}

Enable Logging and Monitoring:

Use AWS CloudTrail or Google Cloud Audit Logs to track access attempts.

Encrypt Sensitive Data:

Enable encryption for all stored data at rest (e.g., AWS KMS or Google Cloud Key Management).

Conclusion:

This exercise highlights the risks of misconfigured cloud storage buckets and demonstrates how attackers can exploit improper access controls to access sensitive data. By enforcing strict access control mechanisms, enabling encryption, and monitoring access, organizations can secure their cloud storage and prevent data breaches.