How to Detect Insider Threats: An In-Depth Guide

Cybersecurity threats don’t exclusively come from external attackers—insider threats must also be considered and mitigated. Insider threats come from employees, contractors or business partners who have legitimate access to IT systems to fulfill business functions. They have access to data and systems that are valuable to cyberattackers or would cause reputational damage if disclosed outside the organization. For example, an insider could leak private company information. To minimize the risk, it’s essential to understand insider threats and put in place both technical and non-technical controls and guardrails.

Key Indicators of Insider Threats

Insider threats originate via three sources:

Negligent Insiders - Everyone makes mistakes. Some of these mistakes can inadvertently expose sensitive data to the wrong people. Some common examples include sending an email to unintended recipients or falling for phishing emails. While these things aren’t done to purposefully harm an organization, the damaging impact can be as severe as malicious actions. This impacts organizations operating in sectors or regions with stringent regulations controlling data access and regulatory fines for data misuse.

Malicious Insiders - Some inside users purposely seek to harm the organization where they have legitimate access to systems and data. Motivations for doing this include financial gain, revenge, political grievances or allegiance to a competing organization. Malicious insiders account for a portion of insider threat incidents, often involving deliberate data theft or system sabotage.

Compromised Insiders - This is a subset of the previous two groups that includes people who have had their access credentials stolen so that attackers can use them to log in. It can also include people who are coerced by criminals via blackmail or bribery to provide access to systems. As compromised insiders typically use legitimate accounts and passwords for access, they can be challenging to spot.

The Growing Threat of Insider Attacks

According to the 2025 report from the Ponemon Institute, the total average annual cost of insider risk incidents has risen to $17.4 million, up from $16.2 million in 2023. The report also highlights a significant increase in the number of insider incidents, which reached 7,868 in 2024. This underscores the critical need for effective insider threat detection and management programs. As such, identifying and mitigating insider threats needs to be front and center in every cybersecurity defense strategy and implementation.

The increase in remote work has also increased the risk of insider attacks. As digital landscapes increase due to remote work, they become more susceptible to sophisticated cyberthreats, including those from within.

Managing insider threats hinges on accurately identifying and reacting to key indicators. Recognizing these indicators in real time can help prevent potentially catastrophic breaches. Indicators of insider threat activities include the following:

Behavioral Anomalies

Changes in user behavior often indicate insider threat activities. Examples include:

Unusual Access Patterns - Accessing files and IT systems that are not part of the user’s core job function. A change in the times a user remotely logs into IT systems or access from new or unknown locations can also indicate threat activity. Multiple failed login attempts can also be an indicator of account credential compromise.

Large Data Transfers – An increase in the volume of data a user downloads or uploads, especially after hours, often signals a data exfiltration attempt. This can happen in several ways, including:

• Email - Sending files to personal email accounts is a common tactic.
• Cloud Storage - Uploading files to cloud services such as Dropbox, iCloud, Google Drive or others when business storage options are available is a red flag that should be spotted, stopped and investigated.
• Physical Media – Copying data using physical USB drives and other removable media is still a common practice. Organizations should monitor for the use of such devices and generate alerts when use is detected.

Privilege Abuse and Misuse Indicators

Privilege escalation or abuse is a red flag for insider threats. Security teams should investigate any employees accessing administrative functions or sensitive systems without the proper clearance. Using Privileged Access Management (PAM) solutions is crucial for controlling access to systems that require elevated permissions. Using accounts with privileged access rights from new or unusual locations can indicate that account details are being shared or compromised. As are attempts to access or modify system logs, as doing so can be used to erase the tracks of malicious activity.

Technical Controls for Insider Threat Detection

Countering insider threats requires both technical and human-centric controls. Below, we outline the technical controls that organizations should consider.

Network Detection and Response (NDR)

NDR solutions monitor and analyze network traffic in real time to detect cyberthreats. They evolved from Network Traffic Analysis (NTA) and User Behavior Analytics (UBA), incorporating advanced techniques such as machine learning and behavioral analytics to identify suspicious activities. NDR tools detect abnormal system behaviors by applying behavioral analytics to network traffic data, uncovering anomalies associated with insider threats even when users log in with valid credentials.

NDR solutions can automate protective actions, such as terminating suspicious network connections and integrate with other security tools to trigger incident responses. This dynamic approach enhances the ability to detect and respond to sophisticated threats, including insider abuse and risky behavior.

Data Loss Prevention (DLP)

DLP solutions help prevent unauthorized data transfers. They monitor data in motion, at rest and in use, using techniques such as content inspection and contextual security analysis to avoid data breaches. A robust DLP strategy helps organizations maintain effective information security.

Privileged Access Management (PAM)

PAM solutions allow only authorized personnel to access sensitive systems and data. Systems governed by PAM require users to request access from administrators using a predefined workflow process. This workflow typically includes multiple approval points, requiring several people to view and approve the access request—like a lock with numerous different keys to open it. PAM systems also usually provide one-time-use access credentials and each session is time-restricted. They log all activities performed during any login and sometimes record videos of actions. These logs and videos provide data for later analysis and review and facilitate easier rollback of any changes if needed.

Endpoint Detection and Response (EDR)

EDR solutions provide in-depth insights into endpoint device activities. They help IT teams detect and respond to threats targeting endpoints before they escalate and infect more devices or servers on a network. They enable security teams to identify malicious activities from external and internal sources quickly. EDR solutions enhance visibility into endpoint security by offering real-time behavior monitoring, detecting and helping prevent malware and enabling file and process monitoring. They also facilitate user activity tracking and provide insider incident response capabilities.

Non-Technical Controls for Insider Threat Detection

Technical solutions are core to detecting insider threats and other cybersecurity risks, but you can’t discount the human factor. Non-technical controls play an equally important role and need to be included in any strategy designed to counter insider threats. These factors focus on the human elements of cybersecurity, emphasizing education, awareness and preventative practices. For example:

Security Awareness Training

It’s crucial to educate employees about the potential risks and consequences of insider threats. Regular and in-depth security awareness training programs empower employees to recognize and respond to suspicious activities from colleagues, reducing the likelihood of accidental or deliberate data disclosures going unnoticed.

Employee Screening and Background Checks

Thorough background checks can help identify potential threats before they become insiders. Employee screenings should be standard practice, as they offer insights into an individual’s history and reduce the risks of hiring a future malicious insider.

Regular Security Audits and Assessments

Regular security audits help identify vulnerabilities and test current security measures and practices. Assessments can pinpoint gaps in an organization’s defenses, enabling updates and improvements in day-to-day practices and the overarching security strategy.

Strong Access Controls and Policies

Implementing strict access controls is a key part of preventing unauthorized access to sensitive systems. Providing employees with access only to the systems and data necessary for their jobs limits the potential for data theft or privilege abuse and reduces the risks associated with information security and insider threats.

Revoking Access from Departing Employees

One common oversight in managing insider threats is failing to revoke access immediately after an employee leaves. This lapse leaves the organization vulnerable to potential data breaches by former employees who still have valid credentials. It’s essential to remove access for departing employees. Failure to promptly deactivate accounts of former staff can result in potential post-employment “insider threats,” even though they are technically no longer insiders. Organizations should follow a workflow whenever an employee or contractor leaves—one that includes removing all their access to IT systems.

Best Practices for Insider Threat Detection

With both technical and non-technical controls in place, organizations should still adopt other best practice measures. Doing so can improve their protection against insider risks. The following items should be considered, implemented and regularly reviewed and updated.

Proactive Monitoring and Threat Hunting

Incorporating proactive monitoring and threat hunting into cybersecurity enhances early detection capabilities. By actively searching for threats instead of passively responding to alerts, security professionals can stay ahead of potential insider threats. Deploying Flowmon platform can help achieve this.

Incident Response and Investigation

Having a tested incident response plan means that security teams can swiftly address any detected threats. Analyzing incidents after they are resolved to understand their root cause feeds into planning and updating response plans to prevent reoccurrences. This ongoing improvement boosts an organization’s cybersecurity posture, as discussed below.

Continuous Improvement and Adaptation

The cybersecurity landscape is constantly changing, necessitating continuous improvement and adaptation of insider threat detection programs (and other cybersecurity defenses). Staying up to date on new technologies and methodologies helps security teams fine-tune cybersecurity practices to counter threats effectively.

Emerging Trends and Future Challenges

The technological landscape is evolving at breakneck speeds and shows no signs of slowing down any time soon. As the landscape changes, the ways that insider threats can surface will also change, as will the methods organizations employ to respond to them. Technologies that will impact this area over the near term include the following.

AI-Powered Threat Detection

AI and Machine Learning (ML) technologies are transforming cybersecurity threat detection by automating the analysis of vast quantities of data. ML-powered solutions are increasingly capable of quickly recognizing subtle insider threat patterns, making it easier to detect insider threat activity. Defenders can use ML algorithms for behavior analysis to boost automated threat detection and predictive analytics. These technologies improve pattern recognition and support adaptive response systems, making organizations more resilient to potential threats.

Zero-Trust Security Model

The zero-trust model is gaining traction as an effective means of mitigating insider threats. Zero-trust networks treat every user and connection as hostile. No access rights or data permissions are given based on the account used or the access location. This limitation in access rights will help reduce the damage that can be done by malicious insiders or by anyone who makes a mistake. To find out more about zero trust, read our guide.

Human Factors and Social Engineering

Understanding human behavior and the psychological tactics employed in social engineering attacks, such as phishing, will play a larger role in mitigation. Attackers often exploit human trust, familiarity or compliance biases to execute insider threats, challenging traditional detection methods. Human factors are increasingly recognized as a critical component of insider threat detection strategies, necessitating a deeper understanding of people’s psychology and behavior.

Conclusion

Insider threats pose a complex and evolving risk to modern technology-based organizations. By adopting a combination of technical and non-technical controls, such as network anomaly monitoring, user behavior analytics, data loss prevention and security awareness training, organizations can effectively detect and deal with various insider threats. Implementing best practices like proactive monitoring and continuous improvement are essential to staying ahead of this dynamic risk. As outlined, the key points to follow in dealing with insider threats are:

• Understanding and categorizing insider threats is foundational to defending against the issue
• Recognizing critical indicators of insider threats is essential for detection and response
• Employing a combination of technical and non-technical controls defines an organization’s posture for dealing with the threat
• Implementing best practices that focus on proactive monitoring, incident response and continuous improvement
• Embracing emerging technologies, such as AI-powered detection and zero-trust models, is essential to developing future-ready security strategies

Organizations must take decisive action to implement robust insider threat detection programs, stay informed about the latest trends and invest in innovative security solutions. As the threat landscape evolves, a vigilant and informed approach will be crucial to improving asset protection against insider threats. Don’t wait for an insider incident to impact your organization. Take action by:

• Implementing a robust insider threat detection program
• Investing in advanced security solutions like Flowmon NDR
• Developing and maintaining robust security policies and procedures
• Staying informed about emerging threats and technologies
• Fostering a security-aware culture within your organization

Remember, insider threat detection is not a one-time activity but rather a continuous journey of improvement and adaptation. The time to start is now.