Chapter 29 Key Takeaways: Cloud Security Testing

Core Concepts

  1. The Shared Responsibility Model Defines Your Testing Scope. Cloud providers secure the infrastructure (security "of" the cloud), while customers secure their configurations, data, and applications (security "in" the cloud). Penetration testers focus on customer responsibilities — IAM policies, storage permissions, network configurations, and application security — not on attacking the cloud platform itself.

  2. IAM Is the Most Critical Attack Surface in the Cloud. Identity and Access Management misconfigurations are the root cause of the majority of cloud breaches. Overly permissive policies, unused credentials, privilege escalation paths through iam:PassRole and policy version manipulation, and poorly scoped roles create exploitable weaknesses that can lead to full account compromise.

  3. Cloud Reconnaissance Differs from Traditional Recon. Instead of scanning IP ranges, cloud recon focuses on DNS analysis for cloud provider CNAMEs, S3 bucket and storage endpoint enumeration, metadata service probing, certificate transparency analysis, and HTTP header inspection. Tools like cloud_enum and manual analysis of application source code reveal cloud footprints.

  4. Storage Misconfigurations Cause Catastrophic Data Exposures. Public S3 buckets, Azure Blob containers, and GCP Cloud Storage have been responsible for some of the largest data leaks in history. Testing must check bucket policies, ACLs, Block Public Access settings, object-level permissions, and encryption configurations. Write access is often more dangerous than read access.

  5. Metadata Services Are High-Value Targets. The EC2 Instance Metadata Service (especially IMDSv1), Azure Instance Metadata Service, and GCP metadata endpoints can leak IAM credentials, network configurations, and user-data scripts. SSRF vulnerabilities that can reach these endpoints are critical in cloud contexts.

  6. Serverless and Containers Introduce New Attack Surfaces. Lambda function misconfigurations (excessive permissions, environment variable secrets, event injection), container escape vectors (privileged mode, mounted Docker sockets, excessive capabilities), and Kubernetes misconfigurations (unauthenticated API servers, overly permissive RBAC) all require specialized testing approaches.

  7. Cloud-Native Tools Are Essential. Pacu (AWS exploitation), ScoutSuite (multi-cloud auditing), and Prowler (AWS benchmark assessment) are purpose-built for cloud security testing. These tools understand cloud-specific attack patterns and produce findings mapped to compliance frameworks.

  8. Cloud Attacks Are Chains, Not Single Exploits. Real-world cloud compromises chain multiple weaknesses: SSRF to metadata access to credential theft to S3 exfiltration, or exposed GitHub credentials to CI/CD pipeline to container registry to production access. Testing must identify and demonstrate these chains.

  9. Infrastructure as Code Review Is Proactive Security. Scanning Terraform, CloudFormation, and ARM templates with tools like tfsec, Checkov, and cfn-nag identifies misconfigurations before they reach production. This "shift left" approach is increasingly part of cloud security assessments.

  10. Provider-Side Vulnerabilities Are Real Risks. Incidents like Azure ChaosDB demonstrate that even when customers do everything right, cloud provider vulnerabilities can expose their data. Defense in depth, application-level encryption, private network access, and rapid key rotation procedures mitigate these risks.

Practical Reminders

  • Always verify cloud provider penetration testing policies before testing begins
  • Scope engagements by account ID, region, and specific services
  • Use IMDSv2 enforcement as both a finding and a remediation recommendation
  • Test S3 access from every credential set you obtain during an engagement
  • Check for credentials in environment variables, source code, and CI/CD pipelines
  • Map IAM privilege escalation paths using Pacu or manual analysis
  • Use CloudGoat and flAWS.cloud for safe, legal practice environments
  • Report findings with cloud-native remediation steps and compliance mappings