The Three Types of Insider Threats That Could Destroy Your Company

When most people think about cybersecurity, they picture hackers in hoodies breaking through firewalls from some remote location. But here’s the uncomfortable truth: your biggest security risk probably has a desk in your office. Insider threats represent one of the most dangerous and often overlooked vulnerabilities in modern cybersecurity – and they’re way more common than you think.

This blog post summarizes the main points of my latest podcast episode. If you’d like, you can listen to it or watch it at https://www.backupwrapup.com/

Look, I’ve been in this industry long enough to see all kinds of security failures, and insider threats are consistently among the most devastating. The reason is simple: these people already have the keys to the kingdom. They have legitimate access to your systems, they know where the valuable data lives, and they understand your security measures well enough to work around them.

The Three Faces of Insider Threats

Not all insider threats are created equal. After years of analyzing security incidents and watching patterns emerge, I’ve identified three distinct categories that every organization needs to understand and protect against.

The Compromised Employee

This is the person who doesn’t want to hurt your company but gets forced into it anyway. Maybe they fell for a phishing attack and had their credentials stolen. Maybe they’re being extorted – attackers got compromising photos or financial information and are blackmailing them into compliance. These people are victims themselves, but they become vectors for attack.

The scary part? This happens more often than you’d think. With AI-generated deepfakes and sophisticated social engineering, attackers can compromise employees in ways that would have seemed impossible just a few years ago. According to recent data, credential theft and account compromise represent a huge percentage of successful breaches.

The Disgruntled Worker

This one’s the classic insider threat scenario. Someone gets fired, passed over for promotion, or feels they’ve been treated unfairly. They still have access to systems – either because nobody bothered to revoke it immediately or because they created backdoors for themselves. And now they’re angry.

I’ve seen this play out in real life, and it’s ugly. People who feel wronged can do tremendous damage on their way out the door. They might delete critical data, steal intellectual property, or plant logic bombs that won’t detonate until weeks after they’re gone. In one case I’m aware of, a fired IT worker had created a backdoor that would check if his account still existed – and when it didn’t, it would start deleting things.

The Infiltrator

This is the most sophisticated insider threat – someone from the outside who specifically gets hired to become an insider. They apply for jobs at target companies, pass background checks, and gain employment with the sole purpose of stealing data or causing damage from within.

These attacks require patience and planning, but they can be incredibly effective. Once someone is on the payroll, they have natural access to systems and data. They can slowly escalate their privileges, map out the network, and execute their plan when the time is right.

Why Traditional Security Fails Against Insider Threats

Here’s the problem: most security measures are designed to keep bad guys out. Firewalls, intrusion detection systems, antivirus software – they’re all focused on external threats. But insider threats are already inside the perimeter. They have valid credentials, authorized access, and legitimate reasons to be touching sensitive systems.

According to research from CISA, 31% of insider threat incidents could have been prevented because someone in the organization knew about potential issues beforehand but didn’t report them. That’s a staggering statistic. It means nearly a third of these attacks succeed not because they’re particularly sophisticated, but because people don’t speak up when they see warning signs.

Even more revealing: 58% of people who committed computer sabotage had communicated negative feelings or grievances beforehand. The warning signs were there – they just weren’t acted upon.

How to Protect Against Insider Threats

So what can you do? Protecting against insider threats requires a multi-layered approach that combines technology, policy, and human awareness.

Implement Least Privilege Access

This is Security 101, but you’d be shocked how many organizations get it wrong. Every person should have exactly the access they need to do their job – nothing more, nothing less. No giving everyone admin rights because it’s easier. No recycling the same root password across all systems.

I love telling the story of that hospital in Portugal that got hit with a massive GDPR fine. You know why? They gave every single employee – including maintenance workers – doctor-level access to patient records. The regulatory body threw the book at them because they hadn’t even tried to implement proper access controls.

Monitor Everything

You need visibility into what’s happening in your systems. Who’s accessing what data? When are they accessing it? What are they doing with it? Modern security tools can establish baselines of normal behavior and alert you when something looks off.

This is where AI and machine learning can actually help. These tools can detect patterns that human analysts would miss – like someone downloading way more data than usual, or accessing systems they’ve never touched before, or logging in from unusual locations.

Have a Culture of Awareness

Remember that stat about 31% of incidents being preventable if someone had spoken up? Create an environment where people feel comfortable raising concerns. If someone seems unusually stressed, angry, or is making concerning statements about the company, there should be channels to report that safely.

This isn’t about creating a culture of suspicion or turning coworkers against each other. It’s about recognizing that humans give off warning signs, and we should pay attention to them.

Implement Immutable Backups

Here’s where I’m going to sound like a broken record, but I don’t care: you absolutely must have immutable backups that no one – not even your most powerful admin – can delete.

Why? Because when an insider threat decides to burn everything down, traditional backups won’t save you. If someone with admin access wants to delete your data and your backups, they can do it. I’ve seen it happen. The only protection is having backups that are physically or logically impossible to delete within a certain timeframe.

This is especially critical for cloud environments like Microsoft 365. An insider with admin access can delete not just the data, but the backups, and even the backup of the backups. Immutable backups break that chain – they create a copy that’s untouchable for a set period, no matter who you are.

The Bottom Line on Insider Threats

Look, I get it – this is uncomfortable stuff to think about. Nobody wants to believe their trusted employees could become threats. But the statistics don’t lie, and the consequences of being unprepared are too severe to ignore.

The good news is that with proper planning, you can significantly reduce your risk. Implement least privilege access controls. Set up comprehensive monitoring. Foster a culture where people feel comfortable raising concerns. And for the love of all that’s holy, get yourself some immutable backups.

Insider threats aren’t going away. If anything, they’re becoming more common as attackers realize that it’s often easier to compromise someone on the inside than to break through external defenses. But with the right approach, you can protect your organization even when the threat comes from within.

Remember: to a hammer, everything looks like a nail. And to me, everything looks like a reason to have better backups. But in this case, I’m absolutely right.

Written by W. Curtis Preston (@wcpreston), four-time O'Reilly author, and host of The Backup Wrap-up podcast. I am now the Technology Evangelist at S2|DATA, which helps companies manage their legacy data