What is Insider Threat?

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STRIDER

Understanding the Hidden Risks Within Your Organization

September is National Insider Threat Awareness Month, a timely reminder that not all security risks come from external hackers. Some of the most damaging incidents originate inside an organization—whether through negligence, malice, or simple human error.

Understanding what an insider threat is, recognizing the warning signs, and building a strong insider threat management program are essential steps for every organization to protect itself from threats—from nation-states actors or others.

In this post, we’ll break down the fundamentals of insider threats, including:

  • What are insider threats and why they matter.
  • Types of insider threats, with real-world examples.
  • Common insider threat indicators.
  • The goal of an insider threat program.
  • Best practices for insider threat prevention and management.
  • Lessons learned from high-profile cases.
  • The future of insider threat detection and mitigation.

What is an Insider Threat?

An insider threat refers to a security risk that originates from within an organization. Unlike external attackers, insiders already have some level of trusted access to company systems, data, intellectual property (IP), or facilities—as well as knowledge of business processes, company policies or other information that would help carry out such an attack. This makes insiders uniquely dangerous, as they can bypass traditional perimeter defenses and exploit their access for malicious or unintended purposes.

But not all insider threats are driven by malice. In fact, many incidents arise from negligence, simple mistakes, or a lack of awareness. An employee who clicks on a phishing email, reuses weak passwords, or mishandles sensitive files can unintentionally create the same level of risk as someone acting with hostile intent. Leaders recognizing this broader spectrum of insider threats is essential to ensuring the security of their organization.

Why Insider Threats Matter

Organizations often spend millions of dollars fortifying their external defenses against cyberattacks, deploying firewalls, intrusion detection systems, endpoint security, and advanced authentication protocols to keep bad actors out. Yet insiders—who are already inside the walls—represent a different class of risk. They have context, privileged access, and the ability to bypass defenses that would stop most outsiders.

In many cases, insider threats remain undetected—and thus uncontained—for longer periods than external attacks. According to a recent report, organizations took an average of 81 days to contain an insider incident (compared to an average of 73 days to contain an external attack) and spend on average $17.4 million annually on activities to resolve these events.

The stakes are high—insider threats can result in:

  • IP theft and economic espionage.
  • Massive data breaches that damage customer trust.
  • Regulatory fines for mishandling personal or sensitive information.
  • Sabotage of critical systems that disrupt operations.

For many organizations, insider threats represent the most difficult and costly category of risk to manage.

Types of Insider Threats

Another challenge is that insider threats are not one-size-fits-all. Organizations should be aware of several distinct categories:

  1. Departing Employees
    Employees leaving the company voluntarily or involuntarily are among the most common insider threats. They might take materials they’re proud of to help land a new job or, more viciously, steal and expose sensitive data out of revenge.

    Example: In 2024, Meta filed a lawsuit against a former vice president of infrastructure who allegedly uploaded a trove of highly sensitive internal documents—including Meta’s “Top Talent” compensation dossier—to his personal Google Drive and Dropbox just before leaving to join an AI startup.

  2. Malicious Insiders
    These are employees or business partners who intentionally cause harm. Motivations often include financial gain, revenge, or loyalty to a competing organization or nation-state. This can also include individuals affiliated with a criminal group or act on behalf of political, social, or activist causes. Additionally, malicious insiders could be privileged users, such as system administrators, who abuse elevated permissions for personal gain or retaliation.

    Example: In 2008, a former Intel design engineer stole trade secrets related to the Itanium microprocessor and transferred them to rival AMD. Intel estimated the value at between $200 million and $400 million. Pani pleaded guilty in 2012 and was sentenced to three years in federal prison.

  3. Negligent Workers
    These are well-meaning employees who inadvertently create risk through carelessness or poor cybersecurity hygiene. This could include clicking on phishing emails, mishandling sensitive data, or using weak passwords.

    Example: In 2017, Boeing notified its employees of a data breach after an employee emailed a spreadsheet to his wife (who was not an employee) hoping she could help him resolve formatting issues. Unbeknownst to the employee, by bypassing security protocols and sending the spreadsheet to both an unsecured device and a non-employee, he compromised the employee ID, place of birth, and social security numbers of approximately 36,000 coworkers, which were located in “hidden” columns of the spreadsheet.

  4. Compromised Insiders
    These individuals have had their accounts or credentials hijacked by external attackers—whether through social engineering, phishing campaigns, credential stuffing, malware, or brute-force attacks—and are then used as unwitting entry points into the organization. This can also include insiders who have been manipulated or coerced into sharing information without realizing the consequences.

    Example: In 2020, Twitter employees were targeted in a coordinated social engineering campaign. Attackers manipulated insiders to gain access to internal admin tools, enabling them to hijack high-profile accounts.

  5. Third-Party Insiders
    Contractors, vendors, and partners who have access to corporate resources can also pose insider threats. Their security practices may not align with the organization’s standards, making them an attractive entry point for attackers. Additionally, threats from third-party insiders could include contractors with divided loyalties, who may be balancing obligations to your organization with ties to another outside entity.

    Example: In the Target breach of 2013, attackers gained access to Target’s network by compromising the credentials of a third-party HVAC vendor. This foothold ultimately allowed them to steal payment information from over 40 million customers, illustrating how weak vendor security can have massive downstream consequences.

Understanding these types of insider threats helps organizations tailor their defenses appropriately.

Insider Threat Indicators

Detecting insider threats early is challenging but critical. Some common insider threat indicators include:

  • Unusual download or file transfer activity, especially involving sensitive data.
  • Repeated attempts to access systems or data outside a user’s normal responsibilities.
  • Use of unauthorized devices or storage media.
  • Sudden behavioral changes, such as disgruntlement or withdrawal.
  • Logging in at unusual hours or from atypical locations.
  • Circumventing established security controls.

While these indicators don’t always signal malicious activity, taken together they can paint a picture of elevated risk. Modern insider threat programs rely on behavioral analytics and AI-driven monitoring to connect these dots in real time.

What is the Goal of an Insider Threat Program?

Every organization should establish a structured approach to mitigate insider risks. But what is the goal of an insider threat program?

At its core, the goal is to protect sensitive data, intellectual property, and operations from insider-driven harm while balancing privacy and trust within the workforce. More specifically, an insider threat program aims to:

  1. Identify: Detect potential risks and suspicious behavior early.
  2. Mitigate: Reduce vulnerabilities through training, monitoring, and access controls.
  3. Respond: Take swift action to contain and remediate incidents.
  4. Deter: Foster a culture of security awareness to discourage malicious intent.

In practice, this means implementing both proactive and reactive measures—ranging from user training and policy enforcement to automated detection tools and incident response playbooks.

Insider Threat Management: Best Practices

Effective insider threat management requires a multi-layered approach that combines technology, processes, and people. Here are some proven best practices:

  1. Implement Least Privilege Access
    Limit user access to only the data and systems they need for their role. Regularly review and adjust permissions.
  2. Monitor User Behavior
    Use behavioral analytics and security information and event management (SIEM) tools to detect unusual activities.
  3. Conduct Regular Training
    Educate employees about security best practices, phishing awareness, and data handling responsibilities.
  4. Establish Clear Policies
    Define acceptable use, data sharing, and reporting protocols. Make sure employees understand consequences for violations.
  5. Secure Third-Party Access
    Vet vendors and contractors carefully, and enforce strict controls on their access.
  6. Encourage a Speak-Up Culture
    Create channels for employees to report suspicious behavior without fear of retaliation.
  7. Leverage Threat Intelligence
    Integrate insider threat programs with external threat intelligence to spot patterns that may indicate targeted recruitment of insiders by adversaries.
  8. Perform Continuous Risk Assessments
    Insider threat management is not static. Regular assessments help organizations adapt as roles, technologies, and business processes change.

Insider Threat Prevention: Building a Security-First Culture

While technology and monitoring tools are essential, the most effective insider threat prevention strategy is fostering a culture of security.

  • Promote Transparency: Employees should understand why security measures exist and how they protect both the organization and individuals.
  • Support Employee Well-Being: Many malicious insider cases stem from disgruntlement or stress. Proactively addressing workplace issues can reduce risk.
  • Reward Good Behavior: Recognize and incentivize employees who follow security protocols diligently.
  • Embed Security in Onboarding and Offboarding: Ensure that employees and contractors are trained in best practices from day one, and that access is immediately revoked upon departure.
  • Simulate Real Scenarios: Tabletop exercises and simulated insider threat incidents can prepare teams to respond effectively.

Prevention is about empowering people as the first line of defense, not just treating them as potential risks.

Lessons Learned from Insider Threat Cases

The real-life examples throughout this article highlight several critical lessons for organizations:

  • Limit Access to What’s Necessary
    Overly broad user privileges create unnecessary exposure. Enforcing least-privilege access reduces the risk of sensitive information being misused.
  • Account for Third-Party Risks
    Vendors, contractors, and partners often have entry points into your systems. Strong vetting, contractual security requirements, and continuous oversight are essential to protect against vulnerabilities outside your direct control.
  • Address Employee Grievances Proactively
    Discontent in the workplace can sometimes escalate into security risks. Open communication, fair treatment, and ongoing engagement help reduce the likelihood of malicious intent.
  • Monitor and Audit User Activity Continuously
    Insider threats can remain hidden for long periods. Regular audits, behavioral analytics, and anomaly detection tools improve visibility and accelerate incident response.
  • Prioritize Secure Offboarding
    Departing employees pose a heightened risk if access rights are not revoked immediately. Structured exit procedures and timely monitoring are critical safeguards.
  • Foster a Culture of Security
    Employees who understand their role in safeguarding information—and feel supported by leadership—are less likely to engage in risky or malicious behaviors. Embedding security into the organizational culture is one of the most effective long-term defenses.

Insider threats are not a hypothetical risk—they’re a proven danger to organizations across all industries. From contractors leaking classified intelligence to employees mishandling sensitive data or vendors leaving a back door open, these incidents show how devastating the consequences can be.

Understanding insider threats, how to identify insider threat indicators, and how to apply robust insider threat management and prevention strategies is no longer optional—it’s a business imperative. By implementing least-privilege access controls, enforcing rigorous vendor oversight, investing in user awareness training, and leveraging advanced monitoring tools, organizations can significantly reduce their exposure.

Ultimately, an insider threat program’s goal is not only to detect and stop malicious actors—but also to create a culture of security where every individual plays a role in protecting the organization. The organizations that succeed will be those that combine people, processes, and technology into a proactive defense strategy—one that adapts as quickly as the threats evolve.