What is an insider threat?

‍Why insider threats happen: The explanation

Organizations rely on employees, contractors, and business partners to operate efficiently, but when these trusted individuals misuse their access — intentionally or unintentionally — it can lead to security breaches, financial losses, and operational disruptions. Whether it’s a malicious insider threat or a mistake caused by negligence, threat detection and strong security measures are crucial to safeguarding sensitive data and preventing data theft.

Learn how security teams detect insider threats with real-time monitoring. Read the Gartner Market Guide insights here

Understanding insider threats in cybersecurity

Cybercriminals aren’t always external attackers. Employees, vendors, and even former staff can gain access to critical assets and exploit weaknesses within an organization. Some do so maliciously, while others make errors that expose customer information or disrupt business operations. Regardless of intent, insider incidents are among the most difficult security risks to detect and mitigate.

Types of insider threats and how to stop them

Organizations face a range of threats, including those from insiders who act deliberately and those who unknowingly put sensitive information at risk. Understanding these types of insider threats is key to implementing security solutions that minimize exposure and prevent data breaches.

1. Malicious insiders

Individuals who intentionally steal, manipulate, or expose sensitive data for personal gain, corporate espionage, or revenge fall under this category. These actors often attempt to bypass security measures, conceal their activities, and exploit privileged access. To prevent, detect, and stop malicious insider threats:

• Implement user behavior analytics to detect unauthorized activity.
• Use threat detection tools to monitor for abnormal data access.
• Apply least privilege access principles to limit exposure to critical assets.

2. Negligent insiders

Human error remains one of the biggest security risks. Employees may misplace devices, fall victim to a phishing attack, or inadvertently share sensitive information, leading to data breaches and compliance violations. To help prevent negligence:

• Conduct regular security awareness training on recognizing social engineering scams.
• Implement multifactor authentication (MFA) to reduce the risk of unauthorized access.
• Use data loss prevention (DLP) technology to monitor and restrict file transfers.

3. Third-party insider threats

External partners such as contractors, vendors, and suppliers may have system access but lack proper security solutions, making them easy targets for cybercriminals. If compromised, they can be used as a gateway to gain access to an organization's most sensitive data. To stay ahead of these insider threats:

• Enforce zero trust security measures to verify every access request.
• Regularly audit third-party permissions and revoke unnecessary access.
• Require vendors to follow strict security measures before integration.

4. Collusive threats

A malicious insider threat working with an external hacker can be extremely dangerous. These actors help cybercriminals bypass security measures, steal intellectual property, or disrupt business operations. To help prevent these types of collusive threats:

• Implement real-time threat detection to flag suspicious collaborations.
• Establish strict logging and monitoring of privileged user activities.
• Conduct regular security risk assessments to identify potential bad actors.

5. Unintentional insider threats

Even well-meaning employees can put an organization at risk. Falling for a social engineering attack, misconfiguring security settings, or accidentally exposing customer information can result in data theft and compliance violations. To help prevent these types of unintentional insider threats:

• Provide mandatory security awareness training on identifying external threats.
• Use email filtering and endpoint protection to prevent phishing attacks.
• Restrict the transfer of sensitive information through security measures like encryption.

Who is most likely to pose an insider threat?

Anyone with access to critical assets and sensitive data could pose a risk, including:

• Current and former employees – Those with active credentials or lingering access
• Contractors and service providers – External users with system permissions
• Privileged users and IT administrators – Individuals with elevated access levels

Key signs of an insider threat

Detecting insider threats requires monitoring user behavior and identifying unusual activity patterns, such as:

• Unauthorized access attempts outside of normal work hours.
• Unusual data transfers, such as excessive file downloads or USB usage.
• Changes to security settings or disabled monitoring tools.
• Frequent login failures from employees who typically don’t make mistakes.

Real-world insider threat examples

The insider threats described above occur in many different ways. Here are some common examples.

1. Employee deletion of critical data after termination

An IT administrator, upset over being fired, accessed company servers and deleted critical assets, resulting in major operational downtime and financial loss.

2. Insider negligence leads to customer data exposure

An employee accidentally forwarded an email containing unencrypted customer information, violating compliance laws and causing reputational damage.

3. Contractor sells intellectual property to a competitor

A contractor with privileged system access stole confidential trade secrets and leaked them to a rival company for financial compensation.

Why insider threats Are a growing concern

The rise of remote work, cloud storage, and interconnected supply chains has increased the attack surface for insider threats. Without proper security solutions, businesses face security risks that could lead to stolen intellectual property, data theft, or even damage to business operations.

How to stop insider threats?

1. Detection Strategies

• Deploy threat detection tools to analyze user behavior and flag anomalies.
• Use privileged access management (PAM) to limit who can access sensitive information.
• Continuously monitor activity for signs of data theft or unauthorized changes.

2. Investigation and Response

• Develop an insider threat response plan for quick containment.
• Conduct digital forensics and internal investigations after an incident.
• Regularly assess security risks to improve future prevention efforts.

3. Prevention and Protection Measures

• Implement zero trust security measures that restrict unnecessary access.
• Require multifactor authentication (MFA) for privileged accounts.
• Educate employees on recognizing social engineering and phishing attacks.