When most people imagine a data breach, the first picture that comes to mind is usually a shadowy hacker in a hoodie, typing away in a dark room. But the reality is often very different. The most damaging threats to a company’s security are not always external attackers—they may be sitting in the next cubicle.
Let’s dive in.
Here’s a number that should make every business pause: 95% of all cybersecurity incidents can be traced back to human error.
Not sophisticated malware. Not nation-state hackers. Just everyday mistakes made by regular people. And those mistakes are costly—the average data breach in 2024 came with a staggering price tag of nearly $5 million.
If firewalls and technical defenses aren’t always the weak point, then where is the real risk? The answer lies with the people inside the organization—the insiders already within the walls.
The most common insider threat is the accidental one. These are not malicious employees but rather well-meaning individuals who, through a simple mistake or deception, cause significant damage.
These risks typically fall into two categories:
In 2016, Snapchat, a company built on the idea of privacy, fell victim to one of the oldest tricks in the book—phishing.
An employee in payroll received what looked like an urgent email from the CEO requesting payroll information. Wanting to be efficient, the employee complied, unknowingly handing over the personal data of 700 staff members, including salaries and Social Security numbers.
This single convincing email bypassed millions of dollars’ worth of cybersecurity infrastructure and forced Snapchat to rethink its approach to employee security training.
Not every breach involves deception. Sometimes it’s just a simple human error.
In one case, an employee accidentally sent a sensitive spreadsheet to an external recipient instead of an internal colleague. Unfortunately, the spreadsheet contained thousands of employees’ personal details—including medical records and home addresses.
That single misaddressed email led to a massive class-action lawsuit and exposed how even the smallest slip-up can lead to enormous consequences.
Then there are insiders who are not careless, but deliberately harmful. Malicious insiders generally fall into two categories:
In 2012, an IT engineer at energy company Enervest learned he was about to be fired. With administrator-level access—the digital “keys to the kingdom”—he retaliated by wiping critical servers.
Years of data and configurations vanished instantly, knocking the company offline for an entire month. The engineer eventually received a four-year federal prison sentence, but the financial and operational damage was nearly irreparable.
In the UK, a supermarket chain, Morrison’s, faced a devastating insider attack when an internal auditor, angry over disciplinary action, leaked payroll data for 100,000 colleagues online.
The leaked details included salaries and bank account numbers, sparking widespread panic and dragging the company through years of high-profile legal battles. It was a stark reminder of how much power a single trusted employee can wield.
After reviewing these stories, one question remains: what can be done?
The answer is not only building stronger technical walls but also strengthening the “human firewall.” This requires four key strategies:
These solutions directly connect to the breaches discussed above. Phishing attacks like Snapchat’s can be mitigated through ongoing awareness training. Revenge-driven sabotage, like at Enervest and Morrison’s, highlights the necessity of strict access controls and monitoring.
The ultimate lesson is clear: in today’s world, adopting a zero trust mindset is no longer optional. This doesn’t mean distrusting your team—it means trusting, but always verifying.
Your employees can be your strongest defense, but without preparation and safeguards, they can just as easily become your greatest vulnerability.