The Most Devastating Confidentiality Breaches in History
Lessons for Businesses and Cybersecurity Experts
Editor’s Note: This post was originally published on March 21, 2025 and has been updated for clarity and structure on June 4, 2025 as part of our 101 Series refresh.
At The Wireless Cable, we explored the foundational principles of cybersecurity in one of our 101 Series posts. Indeed, the three pillars of the CIA Triad (Confidentiality, Integrity, Availability) are of paramount importance in cybersecurity; as they are a framework or model that help guide all policies for information security.
If you recall, or if you’re new here, in cybersecurity the principle of confidentiality -the cornerstone of the CIA Triad- refers to the protection of sensitive information, ensuring that only authorized individuals have access. This data, like personally identifiable information (PII) or state secrets, must be secured at varying levels. But, what happens when that principle collapses; when sensitive data, confidential records or private communications are exposed? The result is often devastating: trust is broken, legal consequences pile up, and the integrity of entire institutions comes under scrutiny.
This post charts a path through four major categories of confidentiality breaches, spotlighting pivotal examples that altered the trajectory of modern cybersecurity. These are not isolated mishaps; they’re turning points. And they hold urgent lessons for governments, companies, and users alike.
TWC: This post is a continuation of our 101 series about the CIA Triad. Here, we will plunge into the confidentiality waters and explore how breaches happen, their consequences, and the critical lessons learned for cybersecurity professionals, policymakers, and organizations. Hopefully this text will make the dark, murky and turbulent tides clearer or at least sailable. By understanding these cases, we can work toward building stronger defenses against future breaches.
How We Organized the Breaches
Through our research, we identified four recurring types of confidentiality failures:
Nation-State Espionage
Leaks and Whistleblowers
Third-Party Compromise
Misconfigurations and Poor Security Hygiene
Each of the following case studies was selected to illustrate a unique facet of these categories. We also include a brief reflection on why each case was chosen, along with additional examples worth exploring.
1. Nation-State Espionage
Case: The Office of Personnel Management (OPM) Hack, 2015
What happened:
A breach at the U.S. Office of Personnel Management led to the theft of security clearance files, fingerprints, and background checks of over 21 million individuals—many in sensitive government roles.
Who was behind it?
Attributed to a Chinese state-sponsored group. Though never formally charged in court, U.S. officials widely accept this attribution.
Why it mattered:
The breach provided adversaries with detailed psychological, behavioral, and financial data that could be used for blackmail, surveillance, or counterintelligence.
TWC Insight: Why we chose this case
OPM demonstrates how strategic intelligence operations can exploit bureaucratic vulnerabilities. It remains a defining case in the national security space.
Other examples: SolarWinds (2020), the Microsoft Exchange hack (2021)
2. Leaks and Whistleblowers
Case: Edward Snowden and the NSA Disclosures, 2013
What happened:
Edward Snowden, an NSA contractor, leaked top-secret documents revealing extensive global surveillance programs run by the U.S. and its allies.
Who was behind it?
Snowden acted independently, motivated by ethical objections to mass surveillance.
Why it mattered:
The leaks reshaped public debates on privacy, spurred global reforms, and exposed controversial programs like PRISM and XKeyscore.
TWC Insight: Why we chose this case
Snowden’s disclosures highlighted the tension between confidentiality and accountability. It forced democratic governments to confront the trade-offs between secrecy and civil liberties.
Other examples: Chelsea Manning’s disclosures to WikiLeaks; Reality Winner’s leak of NSA reports in 2017
3. Third-Party Compromise
Case: Target Data Breach, 2013
What happened:
Attackers gained access to Target’s internal network via stolen credentials from a third-party HVAC vendor. The result: over 40 million credit card numbers stolen during the holiday season.
Who was behind it?
Eastern European cybercriminals, operating via a black market for stolen financial data.
Why it mattered:
It exposed how even trusted vendors can become the weakest link, triggering industry-wide changes in third-party risk management.
TWC Insight: Why we chose this case
The Target breach made third-party security a board-level issue. It was one of the first times that vendor access paths were scrutinized globally.
Other examples: MOVEit Transfer breach (2023); in a stark geopolitical twist which we wrote about here, Israeli forces reportedly planted explosives in walkie-talkies supplied to Hezbollah operatives—weaponizing a trusted communication device to deadly effect. While not a conventional cyberattack, it underscores the extreme and catastrophic potential of tampered third-party gear in high-risk environments.
4. Misconfigurations and Poor Security Hygiene
Case: U.S. Army Intelligence Data Leak, 2017
What happened:
A contractor for the U.S. Army Intelligence and Security Command (INSCOM) misconfigured an Amazon S3 bucket, leaving 100 GB of classified files publicly accessible.
Who was behind it?
No external hacker—this was a case of internal error and oversight.
Why it mattered:
The exposure included virtual disk images of systems used in intelligence operations, potentially compromising missions and lives.
TWC Insight: Why we chose this case
The INSCOM incident is a textbook example of how cloud misconfigurations can nullify even the strongest security policies.
Other examples: Facebook user data leak (2019); Accenture cloud database exposure (2021)
TWC Insight: Confidentiality Isn’t Just About Secrecy
Each of these breaches shows that confidentiality is more than a compliance checkbox. It’s a foundation of trust—between governments and citizens, between companies and customers, between allies and adversaries.
But the threat doesn’t always come from hackers. Sometimes it’s human error, poor configuration, or misplaced trust in a vendor that creates the breach. And as digital infrastructures grow more complex, the margin for error narrows.
To navigate this evolving threat landscape, we must think in systems: of data flows, trust chains, and governance practices. Only then can we prevent the next OPM or Snowden moment.
What to Take Away
Map your risk exposure. Know where your sensitive data lives, who can access it, and how it is protected.
Evaluate third-party relationships. Treat vendor access as a potential attack vector—not a blind spot.
Invest in configuration management. Especially in cloud environments, one error can undo everything.
Foster an internal culture of responsibility. Security is everyone’s job, not just IT’s.
FAQs: What Should I Know About Confidentiality Breaches?
What are the main types of confidentiality breaches?
Confidentiality breaches typically fall into four categories: insider leaks, third-party compromises, misconfigured systems, and targeted attacks. Each presents distinct risks, vectors, and mitigation challenges.
2. What is the most famous insider breach in history?
The Edward Snowden case (2013) is arguably the most globally recognized insider breach, involving the unauthorized disclosure of classified NSA documents to journalists.
3. How can companies prevent third-party data leaks?
Organizations should rigorously vet vendors, enforce contractual security requirements, and monitor third-party integrations. A zero-trust approach helps limit exposure from external collaborators.
4. What’s the difference between a misconfiguration and a hack?
A misconfiguration stems from internal error—such as leaving a database exposed—while a hack typically involves external exploitation of a system's weaknesses. Both can result in major data loss.
5. Why revisit the CIA Triad now?
Despite evolving threats, the principles of Confidentiality, Integrity, and Availability remain the foundation of modern cybersecurity. Reexamining real-world breaches under this lens helps practitioners apply timeless lessons to current challenges.
What’s Next?
This article explored Confidentiality Breaches, the second installment of our CIA Triad Series. Next, we’ll also dive into Integrity and Availability Breaches, uncovering how cyber threats impact data reliability and system uptime. But lookout for a post related to current geopolitcs and of course UN Open Source Week 2025. Lots to cover!
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