A Technical User’s Guide to Insider Threats

It can be daunting to try to build a cybersecurity defense to protect your organization and any sensitive data it may manage. Criminal actors are constantly evolving their tactics and adapting to an ever-changing digital landscape, and threats come from all directions, including within. Insider threats are multifaceted and dynamic, presenting unique challenges for those attempting to secure their enterprise’s sensitive data. Addressing the issues that endanger your business requires understanding the different types of risks, their origins and motivations, the unique hurdles to detection and prevention, and the best practices, tools, and resources available to help protect your enterprise.

What Are Insider Threats?

An insider is defined as “anyone who has access to an organization’s sensitive information or systems.” This includes employees as well as former employees, executives, contractors, partners, board members, and facility staff (such as custodians). Authorized access to facilities, networks, accounts, and servers provides the opportunity for these insiders to damage an organization from within, whether intentionally or inadvertently. There are a variety of insider threat types and motivations, each with its own difficulties, making it impossible to approach insider threat prevention from just one angle.

The three basic types of insider threat, according to the Ponemon Institute’s 2022 Cost of Insider Threats Report, are negligent employees or contractors, criminal and malicious insiders, and credential thieves. Employee or contractor negligence is an accidental insider threat that arises when an insider, through ignorance of security practices, inadvertently causes harm to the organization. This is the least costly per incident, but occurs far more often than the other types and overall accounts for more than 40% of the accumulated cost. Criminal and malicious insiders are those who intentionally set out to harm the business from within, often for financial gain or as a result of a personal vendetta. Credential thieves, by far the most costly type of insider threat per incident, are outsiders who use nefarious means to obtain access to an insider’s account or device in order to infiltrate the organization.

Particular Risks and Challenges

Insider threats present a series of unique challenges that traditional threat detection and prevention tools and measures are not equipped to handle. An insider by definition does not need to exploit vulnerabilities in your defense or launch an attack in order to obtain sensitive data; frequently, they already have authorized access to it as part of their job, so tools designed to keep outsiders out do little to nothing to prevent insiders from exfiltrating data. Malicious insiders also often have the advantage of knowing well in advance when they plan to leave a company, giving them plenty of time to gradually steal data without arousing suspicion.

The actions and behaviors of an insider threat also tend to blend in with normal user behaviors. Downloading, uploading, sharing, editing, and copying data are all common aspects of an insider’s job, and it is complicated to parse which behaviors are legitimate and which are nefarious. It also makes it difficult to follow the flow of data when users are collaborating on files and transferring data constantly. These challenges make it far easier for an insider to deliberately or accidentally leak sensitive data, blurring the line between a suspicious user and a normal one.

Preventing Insider Threat Incidents

Protecting your business against any kind of risk is not a one-and-done security solution, and insider threats are no different. Each organization is unique, but there are some core principles that should be generally effective in mitigating risk. First and foremost, it is important to properly vet all employees before hiring, and then to train them in cybersecurity practices. Employees should understand not just the policies in place but the reasons for those policies and the potential consequences (both to the individual and to the company) of failing to follow them. Implementing the principle of least privilege will also mean that an insider cannot access, and thus cannot steal or leak, critical data and assets that are not necessary for their job.

While those tactics can be effective in preventing negligent or compromised insider incidents, it is more complex and difficult to detect and prevent malicious insiders stealing data or otherwise damaging an organization from within. Fortunately, security tools and solutions exist that can analyze and classify data in ways that make it easier to discern suspicious behavior. It is recommended that security teams research and vet third-party solutions to find one that is trustworthy and effective for their purposes.


While preventing insider threats is no easy task, it is quite possible to build up a defense with the resources and tools available. Ensuring that all employees are adequately vetted in advance, trained in cybersecurity policies and practices, and informed on threat trends can go a long way in preventing negligent insiders and credential thieves. A layered, robust defense should approach insider threats from many angles to cover the various forms and sources they can have, rather than treating them as one single issue.

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