Cloud Storage Attacks

Learning Objectives

By the end of this lesson, you will be able to:

Understand how cloud storage services work.
Learn common cloud storage attack techniques.
Identify storage misconfigurations.
Assess storage security across AWS, Azure and Google Cloud.
Understand data exposure and exfiltration risks.
Apply enterprise storage security best practices.

Introduction

Cloud storage is one of the most valuable assets in any cloud environment.

Organizations store:

Customer information
Financial records
Application backups
Source code
Medical records
Intellectual property
Images and videos
Configuration files
Logs
Database backups

Because cloud storage often contains an organization’s most sensitive information, it is a primary target for attackers.

What is Cloud Storage?

Cloud storage provides scalable object-based storage that can be accessed through APIs, management consoles and applications.

Common cloud storage services include:

Cloud Provider	Storage Service
AWS	Amazon S3
Microsoft Azure	Azure Blob Storage
Google Cloud	Google Cloud Storage

These services are designed for durability and availability, but their security depends largely on correct configuration.

Why Attackers Target Cloud Storage

Cloud storage frequently contains:

Personally Identifiable Information (PII)
Customer databases
Financial reports
Backup archives
API keys
Source code
Secrets
Application logs
Certificates
Intellectual property

A single misconfigured storage bucket can expose millions of records.

Cloud Storage Attack Lifecycle

Storage Discovery

↓

Permission Enumeration

↓

Configuration Analysis

↓

Data Access

↓

Sensitive Data Discovery

↓

Privilege Escalation (if applicable)

↓

Data Exfiltration

↓

Cleanup

Attack Surface

Cloud storage attack surfaces include:

Public buckets
Bucket policies
Access Control Lists (ACLs)
IAM permissions
Encryption settings
Lifecycle policies
Versioning
Cross-account access
Signed URLs
Storage APIs

Each should be reviewed during a cloud security assessment.

Attack 1 — Public Storage Buckets

The most common cloud storage issue is unintended public access.

Example:

Internet

↓

Public S3 Bucket

↓

Sensitive Documents

Common causes:

Misconfigured bucket policies
Public ACLs
Disabled “Block Public Access”
Excessive IAM permissions

Attack 2 — Weak Bucket Policies

Example policy:

{
  "Effect": "Allow",
  "Principal": "*",
  "Action": "s3:GetObject",
  "Resource": "*"
}

Problems:

Public access
Excessive permissions
Data exposure

Policies should follow the principle of least privilege.

Attack 3 — Excessive IAM Permissions

Example:

Developer Role

↓

AmazonS3FullAccess

↓

All Buckets

↓

Sensitive Data

Attackers often exploit over-permissioned identities rather than bucket vulnerabilities.

Attack 4 — Cross-Account Access

Organizations commonly share storage between AWS accounts.

Misconfigured trust relationships may allow:

Unauthorised reads
Unauthorised uploads
Data modification
Cross-account data theft

Always validate cross-account permissions carefully.

Attack 5 — Exposed Backup Files

Cloud storage often contains:

Database backups
VM snapshots
Application backups
Configuration exports

Backup files frequently contain credentials and sensitive information.

Review backup storage separately from production data.

Attack 6 — Sensitive File Discovery

Attackers search for files such as:

passwords.txt
backup.sql
config.yaml
secrets.json
id_rsa
.env
credentials.csv

Poor file management can significantly increase business risk.

Attack 7 — Unencrypted Storage

Sensitive data should be encrypted:

At rest
In transit

Review:

AWS SSE-S3
AWS SSE-KMS
Azure Storage Encryption
Google Cloud Encryption

Encryption protects data even if storage media is compromised.

Attack 8 — Signed URL Abuse

Signed URLs provide temporary access.

Weak configurations include:

Long expiration times
Unrestricted downloads
Public sharing
Poor access monitoring

Signed URLs should be short-lived and monitored.

Attack 9 — Versioning Abuse

Storage versioning protects against accidental deletion.

However, attackers may attempt to:

Recover deleted data
Access historical versions
Download previous files

Review version retention policies during assessments.

Attack 10 — Data Exfiltration

Once access is obtained, attackers attempt to steal data.

Example:

Compromised IAM Role

↓

Amazon S3

↓

Sensitive Files

↓

Download

↓

External Storage

Data exfiltration is often the ultimate objective of storage attacks.

AWS Storage Assessment

Review:

Bucket policies
Public access settings
IAM permissions
Bucket encryption
Versioning
Logging
Lifecycle policies
Cross-account access
Replication
Object ownership

Useful AWS CLI commands:

aws s3 ls

aws s3api list-buckets

aws s3api get-bucket-policy --bucket <bucket-name>

aws s3api get-public-access-block --bucket <bucket-name>

aws s3api get-bucket-encryption --bucket <bucket-name>

Azure Blob Storage Assessment

Review:

Container access level
Shared Access Signatures (SAS)
RBAC assignments
Storage encryption
Soft delete
Versioning
Network restrictions
Private Endpoints

Useful Azure CLI commands:

az storage account list

az storage container list \
  --account-name <storage-account>

Google Cloud Storage Assessment

Review:

IAM policies
Bucket permissions
Uniform bucket-level access
Object versioning
Encryption
Public access
Retention policies

Useful commands:

gcloud storage buckets list

gcloud storage buckets describe gs://bucket-name

Storage Enumeration Checklist

Review:

Bucket names
Public access
ACLs
IAM permissions
Encryption
Versioning
Logging
Object ownership
Replication
Lifecycle policies

Document every storage resource.

Enterprise Scenario

CloudNova Technologies stores customer invoices in Amazon S3.

Assessment findings:

One bucket allows public read access.
Two buckets have no server-side encryption.
Administrator role has unrestricted S3 access.
Backup bucket contains database exports.
CloudTrail logging is disabled for S3 data events.
Object versioning is not enabled.

Potential risks include:

Data exposure
Regulatory violations
Intellectual property theft
Business disruption

Storage Attack Path

Internet

↓

Public Bucket Discovery

↓

Sensitive File Access

↓

Credential Discovery

↓

IAM Enumeration

↓

Additional Buckets

↓

Mass Data Download

↓

Data Exfiltration

Enterprise Deliverables

A professional storage security assessment should include:

Storage Inventory
Public Exposure Report
IAM Permission Review
Encryption Assessment
Cross-Account Access Review
Backup Security Review
Data Classification Findings
Risk Register
Executive Summary

Defensive Controls

Organizations should implement:

Block Public Access
Least Privilege IAM
Server-side encryption
Bucket versioning
Storage logging
Object Lock (where appropriate)
Private Endpoints
Data Loss Prevention (DLP)
Continuous monitoring
Regular access reviews

Best Practices

Enable encryption for all sensitive storage.
Disable unnecessary public access.
Review bucket policies regularly.
Apply least privilege.
Monitor storage access.
Protect backup files.
Rotate credentials.
Enable logging for storage operations.
Review cross-account permissions.
Classify sensitive data.

Common Mistakes

Avoid:

Public buckets.
Wildcard IAM permissions.
Disabled encryption.
Storing credentials in storage buckets.
Ignoring backup security.
Long-lived signed URLs.
Missing audit logging.

Knowledge Check

1. Why is cloud storage a primary attack target?

Answer: Cloud storage often contains valuable information such as customer data, backups, source code and credentials, making it highly attractive to attackers.

2. What is the most common cloud storage misconfiguration?

Answer: Unintended public access through bucket policies, ACLs or incorrect access settings is one of the most common and impactful storage security issues.

3. Why should storage buckets be encrypted?

Answer: Encryption protects data at rest and helps reduce the impact of unauthorised access or storage media compromise.

4. Why should penetration testers review IAM permissions during a storage assessment?

Answer: Excessive IAM permissions may allow attackers to access or modify storage even when bucket policies appear secure.

5. What is the purpose of storage logging?

Answer: Storage logging records access and administrative activity, enabling security teams to detect suspicious behaviour, investigate incidents and support compliance requirements.

Key Takeaways

Cloud storage is one of the most valuable enterprise assets.
Public access and excessive IAM permissions remain the leading causes of storage-related breaches.
Storage assessments should evaluate access controls, encryption, logging and data protection.
Penetration testers must assess storage security from both identity and configuration perspectives.
Strong storage governance significantly reduces the risk of data exposure and exfiltration.

What’s Next?

In the next lesson, we will explore Cloud Compute Attacks, including attacks against Amazon EC2, Azure Virtual Machines, Google Compute Engine, instance metadata services, workload identities and compute misconfigurations.

➡️ Next Lesson: Lesson 09 — Cloud Compute Attacks