Brinztech Alert: CRITICAL: 4TB Unencrypted EY (Ernst & Young) SQL Backup Found Publicly Exposed on Azure

Dark Web News Analysis

The news reports a critical data exposure (a leak, not a hack) at Ernst & Young (EY), a “Big Four” global accounting and consulting firm. A cybersecurity firm, Neo Security, discovered a massive 4TB SQL Server backup file (.BAK) that was left publicly accessible on a Microsoft Azure Blob Storage instance.

Key details of the incident:

• Discovery: Found by Neo Security during routine asset mapping using low-level network tools.
• Verification: The exposure was confirmed without downloading the full file.
  • A HEAD request confirmed the 4TB file size.
  • DNS SOA records linked the storage domain to ey.com.
  • Downloading the first 1,000 bytes revealed the “magic bytes” signature of an unencrypted SQL Server backup file.
• Data at Risk: A .BAK file is a full database dump, which would contain everything in the database: schemas, user data, and critically, client financial data, audit details, PII, internal API keys, credentials, and other secrets.
• Response: After 15 attempts, Neo Security contacted EY’s CSIRT via LinkedIn. EY responded professionally and remediated the exposure within a week.

Key Cybersecurity Insights

This incident provides several critical cybersecurity insights, despite the professional response from EY after notification:

1. Catastrophic “Crown Jewels” Exposure: This is the worst-case scenario for a “Big Four” firm. A 4TB unencrypted SQL backup is not just PII; it’s the “crown jewels” of the firm and its clients. It contains market-moving financial data, audit details, tax preparation data, internal strategies, and system credentials. In the hands of an attacker, this data could be used for financial fraud, insider trading, corporate espionage, and devastating ransomware attacks against EY’s clients.
2. Cloud Misconfiguration: The #1 Cloud Threat: This was not a sophisticated zero-day hack. It was a simple, critical human error: a misconfigured Access Control List (ACL) on an Azure storage bucket, likely set to “public” during a database export. This remains the most common and most devastating vulnerability in cloud environments.
3. The Critical Failure: No Encryption at Rest: The public ACL was the vector, but the catastrophic failure was the lack of encryption. The .BAK file itself was unencrypted. Had the backup file been encrypted before being uploaded to Azure, the public exposure would have been a minor, low-risk incident.
4. “Time-to-Compromise” is Minutes: The article correctly highlights that automated botnets scan the entire IPv4 space in minutes. A 5-minute exposure of a .BAK file is all an attacker needs. “Security through obscurity” is not a strategy; if it’s public, it will be found.
5. Broken Disclosure Process: While EY’s response was praised, the discovery process was flawed. The fact that a security firm had to make 15 attempts via LinkedIn to report a critical vulnerability highlights a major gap. All large organizations (especially a “Big Four”) must have a clear, easily findable “Security” page or security.txt file for responsible disclosure.

Mitigation Strategies

This incident serves as an urgent warning for all organizations using cloud infrastructure.

1. Implement Cloud Security Posture Management (CSPM): This is the #1 defense. Deploy automated CSPM tools to continuously scan all cloud assets (Azure, AWS, GCP) for misconfigurations. These tools can automatically detect and alert on public-facing storage buckets, improper ACLs, and other critical security gaps in real-time.
2. MANDATORY: Encrypt All Backups at Rest: Enforce a strict, non-negotiable policy that all database backups (.BAK, .sql, etc.) MUST be encrypted before being exported or moved to any storage, especially cloud storage. An exposed encrypted file is useless to an attacker.
3. Continuous Attack Surface Management (ASM): Organizations must proactively and continuously map their own external, internet-facing assets (including all storage buckets) just as Neo Security did. “Discover your own leaks first” is a core principle.
4. Establish a Clear Vulnerability Disclosure Program (VDP): Create and prominently display a security.txt file and a “Report a Vulnerability” page on your main website. This gives white-hat researchers a clear, immediate channel, turning a potential crisis into a managed process.
5. Enforce Strict Data Governance & Least Privilege: A 4TB full production backup should never be in a non-production, internet-accessible storage tier. Enforce strict IAM policies, data lifecycle rules, and Data Loss Prevention (DLP) to prevent this data from being exported or exposed by non-privileged users.

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Questions or Feedback? This analysis is based on the provided article. A “Big Four” data exposure, even when handled professionally after the fact, underscores the systemic risk of simple cloud misconfigurations and the absolute necessity of defense-in-depth (like encryption-at-rest). Brinztech provides cybersecurity services worldwide and does not endorse or guarantee the accuracy of external claims. For any inquiries or to report this post, please email: contact@brinztech.com