From Tool Testing to Data Rescue: Exposing a 4GB Cloud Backup Leak

Cloud misconfigurations remain one of the most prominent vectors for data exposure. Often, these leaks aren't discovered through complex exploit chains, but through systematic asset discovery.

While testing Skybrute—an open-source multi-cloud storage brute-forcing tool I developed to scan for bucket exposures across ten different cloud providers—I accidentally stumbled upon a massive, unprotected repository that exposed a decade of corporate communication.

The Discovery

During a routine testing phase of the tool, Skybrute flagged an open Google Cloud Storage bucket with a highly descriptive naming convention:

Upon investigating the public endpoint, I found a single, massive compressed archive: 2015to2025.zip, weighing in at nearly 4 GB.

Analyzing the Exposure

To verify the ownership and impact without violating disclosure boundaries, I performed a superficial review of the contents. The archive was a complete, raw backup of an enterprise Slack workspace spanning a ten-year timeline.

The exposed data included:

• Corporate Directory Data: Full names, corporate email addresses, phone numbers, and office locations for over 1,000 employees.

• Personally Identifiable Information (PII): Sensitive employee onboarding documentation and internal HR records.

• Communication Logs: A decade of internal chat histories, direct messages, project channels, and attached files.

Leaving an unauthenticated, downloadable link to a company's entire historical communication history on a public cloud bucket is equivalent to leaving the front door to the corporate headquarters wide open.

Rapid Remediation & Takeaways

I immediately identified the affected organization and initiated a responsible disclosure report detailing the exposed bucket path.

The company's security team handled the incident exceptionally well: the bucket was locked down and restricted within 30 minutes of receiving my report. This rapid response completely mitigated the window of opportunity for malicious actors to scrape the archive.

This accidental finding underscores three critical points for modern security engineering:

1. The Risk of Secondary Buckets: Organizations often secure their primary infrastructure but neglect legacy, backup, or staging buckets named similarly to their core brand.

2. The Power of Continuous Scanning: Proactive automation via asset enumeration tools is vital for identifying exposures before they are indexed or exploited.

3. Fail-Safe Cloud Defaults: Cloud storage permissions should explicitly enforce private IAM policies unless public access is strictly required by design.

For updates on open-source tool development and cloud security research, follow my work on X: @siratsami71.