An Insider Threat A-Z: What All Security Pros Need to Know


Tech Insights for ProfessionalsThe latest thought leadership for IT pros

Thursday, March 16, 2023

What are insider threats and how do they harm businesses? Read on to learn everything you need to about these cyber risks.

Article 8 Minutes
An Insider Threat A-Z: What All Security Pros Need to Know
  • Home
  • IT
  • Security
  • An Insider Threat A-Z: What All Security Pros Need to Know

Cyber threats are now big business, and issues such as data breaches can be hugely costly. Indeed, IBM states that in 2022, the average breach cost firms $4.35 million, and the long-term expenses can last many years, from dealing with backlogs of work to restoring a brand's reputation to hardening networks.

But not every breach is the result of shadowy hackers targeting your systems. In many cases, the danger actually lies much closer to home, with your own employees. These are called insider threats, and they can often be much harder to stop than third-party intrusions. So what do you need to know about these risks?

What is an insider threat?

As the name suggests, insider threats originate inside your business. Broadly, they're defined as any cyber security incident that is the direct result of actions taken by someone within the targeted organization, rather than an outsider.

So how does an insider threat occur? There are several ways these threats can happen. It might be through the careless or deliberate actions of a current employee, or be caused by a former worker who has retained access to key systems, or taken critical data with them when they leave the business. However, the common threat is that private and sensitive information is exposed, or systems are damaged.

What are the main types of insider threat?

In general, insider threats fall into one of two main categories, either accidental or deliberate. However, there are degrees within this, so it's often more accurate to split such incidents into three key types. These are:


Careless or reckless behavior is the most common cause of insider threats, with Gartner estimating 90% of incidents fall into this category. There is no intention to cause harm, but it may involve an individual either knowingly acting in an inappropriate manner, or failing to follow basic security processes. This may be losing a device in a public place, clicking on a malware-infected email link, reusing easily-guessed passwords across multiple accounts or deliberately skipping security verification processes in the name of convenience. 

The line between everyday carelessness and more serious negligence can sometimes be blurry, but often, you can ask whether the employee should have known better. If they're wilfully ignoring processes or failing to remember basic security training, this should be addressed. 


In some cases, employees may have been unknowingly compromised by external actors. This could involve being manipulated into malicious activities they believe to be legitimate, such as sending data to hackers posing as an executive, or allowing an unauthorized user access to a system.


Sometimes referred to as malicious insiders, this is often the most dangerous type of insider threat. This is because these individuals know exactly what they're doing, have a specific intent to do harm and will often be taking steps to cover their tracks.

They could be doing this for financial gain, such as stealing intellectual property to sell or take to a new company, or just be motivated by a desire for revenge for some perceived slight, in which case the goal may be to do as much damage as possible.

Type Malicious Motivation Example
Negligent No Carelessness Leaving laptop with company data in public space
Compromised No Unaware of risks Falling victim to business email compromise scam
Deliberate Yes Financial or vengeful Ex-employee stealing company IP to sell to competitor

What are the characteristics of an insider threat?

Being able to spot an insider threat is vital if firms are to protect their most valuable assets. So what makes them so dangerous, and what characterizes them as threats to look out for?

  • Privileged access: While employees are the most common source of insider threats, anyone who has high-level, non-public access to a system can be a risk. This includes contractors, vendors, executives and even interns. 
  • Hard to spot: Insiders often need this privileged access to do their jobs, so there's often nothing unusual about their activities that would raise red flags with security tools such as access monitoring.
  • Difficult to prevent: Many cybersecurity defenses such as firewalls and antimalware tools are focused on preventing people from entering the network, and aren’t designed to look inwards at threats that are already within the company network. 
  • Strong motivation: Malicious insiders often have very powerful motives for targeting their company. For example, they may hold a grudge if they feel they've been mistreated. This makes them very determined and tough to stop.

Which industries are at risk of insider threats?

While any company can fall victim to insider threats, those that hold especially sensitive data, such as intellectual property, trade secrets or financial details, may be the most at risk. These include:

  • Healthcare: These firms carry highly sensitive data, making them a prime target for tactics like extortion. According to Verizon, these organizations see more incidents of employees misusing privileged access than any other sector, with almost twice as many incidents as the second-placed sector (professional services).
  • Finance: Unsurprisingly, the valuable financial data these organizations hold make them tempting targets. According to the Ponemon Institute, this industry spends more than any other on dealing with these activities, at $21.25 million a year as of 2022.
  • Tech: Big tech firms also hold a wealth of highly sensitive data such as proprietary code and the personal information of hundreds of millions of users. Indeed, famous insider threat cases involving tech firms include names such as Microsoft, Cisco and Twitter, showing that even the biggest brands can be compromised by their own employees.

Why do insiders pose such a significant threat to an organization? 

Insider threats pose such a big problem because they are carried out by people who will be working with highly confidential information and applications every day. This means that even in cases of carelessness, rather than malice, it may only take a minor error to expose data or take mission-critical systems offline.

In worst-case scenarios, malicious insiders know exactly what information is of the greatest value or will do the most damage - and how to access it. This means they’re able to effect much more highly targeted attacks than an outsider would be able to achieve.

Therefore, the expenses caused by insider threats can be significant. For instance, Proofpoint's 2022 Cost of Insider Threats Global Report revealed that it costs the average organization $15.4 million a year to remediate these threats - a 34% rise from 2020.

The report also revealed it takes firms an average of 85 days - almost three months - to detect an insider threat. This indicates the need for better detection and prevention methods such as close monitoring of privileged user accounts.

How to detect an insider threat

With the right tools, however, firms can improve their detection speeds and shut down insider threats before they have a chance to exfiltrate valuable data. To achieve this, businesses should be looking at both behavioral indicators and digital red flags.

Behavioral indicators of an insider threat include:

  • Changes in employee attitude or performance
  • Working outside normal hours
  • Sudden interest in areas outside their job role
  • Vocal disagreement with company policies/direction
  • Frequent overseas travel
  • Unexpected resignations 

Digital alarm bells may include:

  • Unusual or repeated login attempts
  • Data transfers outside office hours
  • Accessing data or applications not used before
  • Use of unauthorized storage devices such as USB sticks
  • Large volumes of data downloads

How to protect against an insider attack: 5 best practices

However, spotting an insider threat is one thing. But stopping it is another challenge altogether. Fortunately, there are several steps you can take to improve your chances of both falling victim in the first place and shutting down any incident before it can cause damage.

  • Enforce security policies: Ensuring policies such as access management, two-factor authentication, strong passwords and banning account sharing are fully enforced makes it harder for insiders to access data.
  • Watch your critical assets: Technologies that can monitor when, where and who is accessing data are vital to spotting malicious insiders. Combine this with advanced endpoint protection that can warn you when data is leaving the network to stand the best chance of success.
  • Educate your staff: Prevent incidents caused by negligence by fully training your employees on security essentials. Spotting phishing emails, not sharing login details and even ensuring they don't hold secure doors open for people reduces your risk.
  • Have a threat hunting team: Unlike most cybersecurity measures, which is a reactive process, threat hunters actively seek out vulnerabilities and risks in your business, analyzing data to spot red flags. 
  • Integrate threat intelligence: Threat intelligence software lets you monitor all network activity in real time. As well as detecting an insider threat quickly, it can understand how best to respond and prevent it from doing damage.

Final thoughts

Insider threats will always be a major risk for any business, regardless of size or sector. After all, you can never predict who might make a mistake that compromises data, or why an individual may decide to act on whatever grudges they may be holding.

However, having a strong insider threat program that understands exactly how these incidents are caused and what they look like can help you shut them down quickly. As these risks can cost firms millions of dollars if left undetected, investing in preventative steps and effective monitoring tools play vital roles in preventing these attacks before they have a chance to harm you.

Tech Insights for Professionals

The latest thought leadership for IT pros

Insights for Professionals provide free access to the latest thought leadership from global brands. We deliver subscriber value by creating and gathering specialist content for senior professionals.


Join the conversation...