Malicious Insiders: Types, Characteristics, and Indicators

While organizations are spending a good deal of money protecting their data against unauthorized access from the outside, malicious insiders may pose no less harm. According to the “Verizon 2024 Data Breach Investigations Report”, 35% of all data breaches experienced by large organizations in 2023 were caused by internal actors.

Organizations that become victims of malicious insider threats face many negative consequences: from loss of confidential data, revenue, and clients to reputational harm or even going out of business. Let’s look closer at how your organization can detect malicious insiders before they cause harm.

What is a malicious insider?

The Computer Emergency Response Teams (CERT) Insider Threat Center defines a malicious insider as one of an organization’s current or former employees, contractors, or business partners who intentionally exceed or misuse their authorized access in a manner that negatively affects the confidentiality, integrity, or availability of the organization’s information or information systems.

Malicious insiders are harder to detect than outside attackers, as they have legitimate access to an organization’s data and spend most of their time performing regular work duties. Thus, detecting malicious insider attacks takes a lot of time and effort. The 2025 Cost of Insider Risks Global Report by the Ponemon Institute states that it takes an average of 81 days to detect and contain an insider-related security incident.

Types of malicious activity

In the Common Sense Guide to Mitigating Insider Threats, CERT classifies the activities of malicious insiders as follows:

• Intellectual property (IP) theft is the unauthorized acquisition of sensitive business information, such as trade secrets, source code, scientific research, or proprietary designs. According to CERT researchers, more than half of IP theft cases involve technical personnel — developers, researchers, engineers — whose skills and access level enable them to discreetly extract large volumes of data. Common triggers include financial need, job dissatisfaction, a desire to aid a new employer, or the belief that the stolen work belongs to them.
• IT sabotage is an abuse of information technology to direct specific harm to an organization or individual. These attacks are also usually performed by system administrators, programmers, or other technically savvy employees who can hide their malicious actions and disable an organization’s operations. These people are typically motivated by a desire to get revenge for a negative work experience, and they generally execute their attacks during employment or shortly after termination.
• Fraud involves gaining unauthorized access to or modifying an organization’s data. Usually, the motivation for fraud is personal gain or data theft with the intention of identity theft or credit card fraud. These attacks are usually committed by employees in finance, accounting, or executive roles who can manipulate records, issue unauthorized payments, or access personally identifiable information (PII). In most cases, these people are motivated by greed or financial pressure.
• Espionage is the unauthorized collection and transfer of an organization’s sensitive information, such as trade secrets, customer data, or strategic plans, for the benefit of a foreign government or competing entity. Espionage is typically conducted by trusted insiders with legitimate access, such as engineers, researchers, or project leaders, and can be motivated by ideology, pressure, or profit.

It’s important to understand that attacks by malicious insiders are rarely committed randomly, as insiders usually thoroughly plan their actions in advance or act after a triggering event. Understanding a user’s path to committing a malicious act is key to identifying potential threats from malicious insiders early and preventing damage before it occurs.

How trusted users become malicious insiders

CISA’s Insider Threat 101 Fact Sheet outlines six distinct stages that mark an insider’s path leading up to a malicious incident.

1. Grievance and ideation

A user’s malicious intentions against your organization are often triggered by an emotional response to injustice or a personal setback. This could result from professional rejection, financial problems, social conflicts, or ideological differences. Over time, the user holds onto these negative emotions and starts to believe that causing harm to your organization is justified. If the user’s frustrations aren’t addressed, they may take their first step toward committing a malicious act.

2. Preparation

In this stage, the user moves beyond frustration and starts planning how to inflict the most damage. They may start by identifying tools, gathering information, or looking for weaknesses in your systems or workflows. Malicious actors may also begin stealing sensitive files or manipulating processes. While some individuals abandon their plans at this stage, others feel increasingly committed — especially if the root of their negative emotions remains unresolved.

3. Exploration

What distinguishes this stage from the others is the shift from planning to testing how, when, and where they can act with the least chance of detection. Insiders may investigate system vulnerabilities and evaluate which assets of your organization are most valuable. Sometimes, they attempt to involve other employees.

4. Experimentation

At this point, the insider can begin testing parts of their plan in real-world conditions. They may attempt to access restricted areas, run scripts, or simulate hostile attacks to see how your organization’s security system responds. These tests help them evaluate risks and adjust their plan accordingly. If no response follows, the insider may feel encouraged to move forward with their malicious actions.

5. Execution

The insider carries out their plan at this stage. They use their access and knowledge of your internal systems to steal data, sabotage operations, damage infrastructure, etc. They choose the moment of attack carefully to avoid detection and cause maximum harm. If you haven’t detected any warning signs by now, you might not discover the threat until it has already caused damage.

6. Escape

After the incident, the malicious insider focuses on avoiding consequences. They may try to tamper with evidence or mislead investigators. Some may leave the organization right away, while others stay on so they can continue to exploit their access. 

With this blueprint in mind, let’s now delve into several key behavioral and technical indicators of an employee gone rogue who may pose a malicious threat to your organization.

Behavioral indicators of malicious insiders

Not all employees become malicious insiders, so there’s no need to cast suspicion on everyone. When hiring, pay attention to the following signs of a potentially risky insider:

• Background checks including official records of arrests, harassment, hacking, or security violations at former workplaces
• History of non-compliance with corporate policies
• Falsification of hiring information
• Cases of unprofessional behavior
• Abusive behavior towards other employees
• Personality conflicts
• Misuse of travel, time, or expenses at former workplaces
• Conflicts with former coworkers or supervisors

Behavioral indicators can also appear during employment with your organization and signal an employee’s disgruntlement and potential readiness to take malicious actions. Your human resources (HR) department should pay closer attention to employees or contractors who:

• Violate corporate policies
• Have conflicts with colleagues
• Perform poorly
• Are deeply interested in projects they aren’t involved in
• Use sick leaves too often
• Work without vacations

In these cases, the HR department should discuss the reasons for this behavior with the employee and try to facilitate a solution. They also should inform security officers so they can conduct targeted technical monitoring of the employees in question. While there may be no signals of an ongoing attack during these periods, it’s important to constantly monitor suspicious events and detect anomalies.

Technical indicators of malicious insiders

Technology-related indicators of a malicious insider threat in your midst include actions that involve computers or electronic media. To execute their attacks, insiders may misuse legitimate authorized access to critical corporate data or create a new path in order to access unauthorized assets and conceal their identity or actions. Let’s look at some indicators of different types of malicious insider activities — IP theft, sabotage, fraud, and espionage — and examples of real-life breaches.

Indicators of IP theft

In cases of IP theft, insiders try to access, steal, and share critical data with competitors or future employers, or keep it for personal use. Since insiders may have regular access to data when performing their duties, it can be quite difficult to detect data theft. However, security officers should pay attention to the following actions that may be a sign of data exfiltration:

In 2024, Google sued former engineer Harshit Roy for leaking proprietary chip designs. Roy, who had worked on hardware for Google Pixel devices, left the company and later began sharing detailed specifications of Google’s chip technology on X and LinkedIn. He even tagged Google’s competitors like Apple and Qualcomm to exacerbate the damage caused by the IP disclosure.

Indicators of sabotage

In cases of sabotage, insiders aim to damage an organization’s systems, operations, or reputation. Сertain activities may serve as early warning signs of potential sabotage:

Sabotage can cause serious operational and reputational harm. In 2023, Tesla became the target of an incident in which two former employees leaked sensitive employee data to a foreign media outlet. The breach compromised the names, addresses, phone numbers, employment histories, and Social Security numbers of over 75,000 individuals. This case illustrates how insider sabotage doesn’t always involve direct system damage — it can also result in large-scale data exposure.

Indicators of fraud

Typically, fraud includes making changes to data files that benefit the malicious insider through some small financial reward. While these actions are hard to notice, the fraud can continue as long as the attacker wants. Insiders can also abuse their legitimate access privileges and sell data to external parties who can then carry out identity theft.

In 2024, Paul Steed, a Global Price Risk Manager at Mars Wrigley’s Global Cocoa Enterprise, exploited his position to embezzle more than $28 million from the company. He carried out a complex plan by creating fake invoices and misusing export credits, using the stolen money to buy personal items, and sending over $2 million to accounts in Argentina.

Indicators of espionage

Insiders involved in espionage use their access to gather and leak valuable internal data to outside groups. The user actions listed below may point to potential attempts at espionage:

In 2025, Keith O’Brien, a former employee at HR tech company Rippling, used his access to spy for a competitor company, Deel. He was secretly recruited by Deel’s CEO and paid €5,000 (~$5,500) a month in cryptocurrency to steal confidential information. O’Brien was pulling information from services like Slack, Salesforce, and Google Drive — mainly about payroll plans and customer details — until he was discovered by Rippling’s security team. 

Fortunately, with the help of dedicated tools for employee activity monitoring and insider threat detection, security operators and system administrators can spot the early signs of malicious activity before irreversible damage occurs.

Prevent malicious insider activity with Syteca

Syteca is a cybersecurity platform that secures organizations against insider threats. Syteca ensures robust protection of internal systems and assets by enabling you to control access permissions, get real-time visibility into user actions, and swiftly detect and respond to suspicious activity.

Syteca limits insider threat exposure by granularly controlling who can access sensitive systems and data and under what circumstances. With Syteca, you can enforce the principles of least privilege, just-in-time access, and zero trust security to make it much harder for malicious insiders to misuse access permissions or escalate their level of access. Syteca Privileged Access Management (PAM) enables you to:

• Regularly identify unmanaged privileged accounts in your IT environment
• Verify user identities with two-factor authentication
• Control endpoint access with one-time passwords
• Establish access request and approval workflows
• Record privileged user sessions
• Secure corporate account credentials

Syteca User Activity Monitoring (UAM) helps you oversee all activity inside your infrastructure and look for unusual events while respecting user privacy. By continuously monitoring user activity across endpoints, Syteca allows security teams to spot the early signs of malicious insider threats. With Syteca UAM, you can:

• Record users’ on-screen activity or watch it live
• Log and search through metadata
• Monitor users’ keystrokes
• Manage the use of USB devices
• Generate user activity reports for IT security audits
• Export user sessions for forensic investigation

When suspicious activity occurs, Syteca doesn’t just send real-time notifications to your security team — it makes it easy to take quick, effective action. Rule-based alerts and response actions empower security teams to address incidents driven by malicious insiders before they damage your organization. Syteca lets you:

• Use a library of preconfigured alerts that can detect:
  • deployment of hacking software
  • sharing files via cloud-based services
  • visits to FTP websites, etc.
• Tailor custom alerts to address your unique security needs
• Automate incident response by configuring rules that can:
  • display warning messages to users
  • block unauthorized USB devices
  • block malicious users
  • kill harmful processes

Whether deployed on-premises, in the cloud, or in hybrid environments, Syteca easily integrates with your infrastructure. The platform is designed for fast deployment and scalability, allowing you to secure your environment quickly and efficiently adapt as your organization evolves.

By leveraging Syteca, you can strengthen your cybersecurity defenses and reduce security risks from malicious insiders to your organizational assets.

Conclusion

Detecting a malicious insider is a complicated task for organizations. However, with close cooperation between security teams and other departments in your organization, you can identify the early indicators of an insider attack and stop it before any damage occurs.

With the Syteca cybersecurity platform, you can not only swiftly detect insider threats but also enhance the preventive measures your organization takes to combat malicious activity.