Shocking Discovery: Google Cloud Composer Vulnerability Puts GCP Projects at Risk

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Introduction to the Cloud Composer Vulnerability

In April 2025, security researchers unveiled a critical vulnerability in Google Cloud Composer, aptly named “ConfusedComposer.” This privilege-escalation flaw had the potential to allow attackers with limited permissions to escalate their access, targeting the backbone of Google Cloud Platform (GCP) operations. The vulnerability has since been patched, but it raises essential concerns about service account management and orchestration in cloud environments.

What is Google Cloud Composer?

Google Cloud Composer is a fully managed workflow orchestration tool that’s built on Apache Airflow. It’s used to automate, schedule, and monitor workflows such as data pipelines and ETL jobs in GCP.

Timeline of the “ConfusedComposer” Flaw

The vulnerability was uncovered by Tenable researchers and responsibly disclosed to Google, leading to a swift patch rollout. The issue, however, exposed thousands of GCP projects to potential privilege escalation attacks before it was fixed.

Technical Breakdown of the Vulnerability

Root Cause: Cloud Composer’s Interaction with Cloud Build

At the heart of the vulnerability was how Cloud Composer interacts with Google Cloud Build—GCP’s CI/CD service. Composer used Cloud Build to install custom Python packages (PyPI modules), inadvertently handing over excessive privileges to an insecure component.

Custom PyPI Packages: A Hidden Risk

When users added custom PyPI packages, Composer would spin up a Cloud Build environment, unknowingly providing it with a highly privileged service account. This setup became the entry point for attackers to inject malicious code.

How the Exploit Works in Real Environments

Malicious PyPI Package Injection

An attacker with composer.environments.update permission could modify environment configurations to include a malicious PyPI package. Once Composer triggered the build, this package’s install scripts were executed automatically.

Role of Pip Scripts and Metadata API Access

Using pip’s pre-install and post-install hooks, attackers could run arbitrary code. This code accessed the Cloud Build metadata API, extracted tokens, and misused the Cloud Build service account to access sensitive GCP resources.

Impact of the Vulnerability on GCP Environments

Elevated Access via Service Account Tokens

The compromised Cloud Build service account had broad permissions across the GCP project, including access to:

• Google Cloud Storage
• Artifact Registry
• Container Registry

Project-Wide Risks to Storage, Registry, etc.

Once the attacker obtained the token, they could manipulate or steal data, deploy malicious artifacts, or control containers—essentially breaching the cloud environment.

Google’s Mitigation and Fixes

Switching to Composer Environment Service Accounts

Google’s fix involved switching from using the Cloud Build service account to the Composer environment’s dedicated service account for installing PyPI modules. This limits access and follows the principle of least privilege.

Timeline for Fix Deployment

All new Composer environments include the fix. Existing environments are scheduled for automatic updates by the end of April 2025.

Tenable’s Role in Discovery

The Jenga Attack Class

Tenable categorized this as part of a broader “Jenga” attack class, building on their prior discovery named “ConfusedFunction.” These attacks target interconnected services and misconfigured permissions within cloud infrastructure.

How Tenable Tracked and Reported the Issue

The team leveraged security telemetry and performed targeted testing to simulate real-world attack paths, eventually demonstrating a full privilege escalation scenario.

Lessons Learned for Cloud Security Professionals

Misconfiguration Risks

Even well-architected services can become vulnerable when automation intersects with over-permissioned service accounts. This incident underscores the need for vigilant permission management.

Secure Handling of Service Permissions and Automation

Organizations should isolate environments, monitor inter-service permissions, and audit automation pipelines regularly.

Best Practices to Prevent Similar Exploits

• Implement Role-Based Access Controls (RBAC)
• Restrict Custom Package Installations
• Regularly Audit Service Accounts
• Use Logging and Monitoring Tools
• Keep Dependencies Up to Date

Future Implications for Cloud Orchestration Tools

Apache Airflow and Other CI/CD Services

While Composer is based on Airflow, the risk applies to any CI/CD service using dynamic service provisioning. This includes tools like Jenkins, GitHub Actions, and GitLab CI.

Rise of Cross-Service Vulnerabilities

Attackers are increasingly exploiting trust relationships between services. Tools need better boundaries, while admins must gain visibility into orchestration internals.

How Technijian Can Help Safeguard Your GCP Environment

Technijian offers comprehensive cloud security solutions designed to address vulnerabilities like ConfusedComposer before they happen. Here’s how we help:

• ✅ Cloud Security Audits: In-depth analysis of your GCP configurations, permissions, and orchestration workflows.
• ✅ CI/CD Pipeline Hardening: We lock down inter-service interactions and ensure minimal access at every automation step.
• ✅ Real-Time Monitoring and Alerts: Get notified of suspicious actions like privilege escalations and unauthorized token usage.
• ✅ Managed Security Services: Let us manage your security posture while you focus on innovation.

Contact Technijian to learn more

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Frequently Asked Questions (FAQs)

1. What is the Google Cloud Composer vulnerability?

It’s a privilege escalation flaw in GCP where attackers could misuse Composer’s package install process to gain elevated permissions.

2. Is my environment affected?

If you used Cloud Composer with custom PyPI packages before April 2025, you might have been exposed. Google has since patched the issue.

3. What did attackers exploit?

They exploited the automatic service account provisioning via Cloud Build triggered by Composer.

4. Has the issue been resolved?

Yes, Google has implemented a fix, and all new Composer environments are secure.

5. How can I secure my GCP environment?

Implement RBAC, restrict automation permissions, and conduct regular security audits.

6. Why choose Technijian for cloud security?

We specialize in protecting complex cloud infrastructures, with tailored solutions for Google Cloud users.

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Conclusion

The ConfusedComposer vulnerability offers a wake-up call to all GCP users and cloud professionals. As cloud orchestration grows more complex, security must evolve in tandem. By understanding and addressing the risks posed by service account misconfigurations, organizations can better protect their digital ecosystems.

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