Insider Threats

Your biggest asset is also your biggest risk and the root cause of insider threats: people. Yet most security tools only analyze computer, network, or system data. Insider threats have reached unprecedented levels, with 83% of organizations reporting at least one insider attack in the past year.

High-profile cases like Tesla’s 2023 data breach, where two former employees leaked sensitive information of over 75,000 workers to foreign media, demonstrate how devastating these internal risks can become. With the average cost of insider incidents reaching $15 million and 48% of organizations reporting that attacks have become more frequent over the past 12 months, insider threats are one of the most pressing cybersecurity challenges facing modern enterprises.

An insider threat is when someone misuses their authorized access to negatively impact a company’s critical information or systems. This person does not necessarily have to be an employee. Third-party vendors, contractors, and partners could also abuse their access.

“Insider threats arise from careless users, users with compromised credentials, or users who seek to cause harm intentionally,” says Stephanie Torto, Senior Product Marketing Manager at Proofpoint. “The latter type of user—the malicious insider—can be the most daunting for security teams to manage. It requires them to analyze a user’s behavior and determine whether they have bad intentions.”

Malicious insiders abuse their access for personal gain, revenge, or competitive advantage—stealing intellectual property, selling confidential data, or sabotaging systems. Current statistics show that 74% of cybersecurity professionals are most concerned with these intentional bad actors, a significant increase from 60% just five years ago. Financial gain drives 89% of malicious insider breaches, though workplace grudges, espionage, or ideological beliefs also play a role.

However, malicious intent is not the only driver of insider threats. Negligent insiders create security risks through careless actions, poor security practices, or simple human error—like clicking phishing links, misconfiguring systems, or accidentally sharing sensitive data. Compromised insiders are another category where external attackers exploit legitimate credentials through techniques like credential theft or social engineering to gain insider access.

What Is an Insider?

An insider is any person who has or had authorized access to or knowledge of an organization’s resources, including personnel, facilities, information, equipment, networks, and systems. This definition extends beyond traditional employment relationships to encompass anyone granted trust and access by the organization.

According to CISA, an insider is someone the organization trusts with sensitive information, access privileges, or knowledge that could potentially harm the organization if misused. The key difference is not employment status, but the level of access and trust given to the individual; a current or former employee, contractor, or business partner who has or has had authorized access to the organization’s network, systems, or data. Examples of an insider may include:

• A person the organization trusts, including employees, organization members, and those to whom the organization has given sensitive information such as financial data, business strategy, and organizational strengths and weaknesses.
• A person given a badge or access device identifying them as someone with regular or continuous access (e.g., an employee or member of an organization, a contractor, a vendor, a custodian, or a repair person).
• A person to whom the organization has supplied a computer and/or network access.
• A person who has intimate knowledge about and possibly helps develop the organization’s products and services; this group includes those who know the secrets of the products that provide value to the organization.
• A person who is knowledgeable about the organization’s fundamentals, including pricing, costs, and organizational strengths and weaknesses.
• A person who is knowledgeable about the organization’s business strategy and goals, entrusted with future plans, or the means to sustain the organization and provide for the welfare of its people.
• In the context of government functions, the insider can be a person with access to protected information, which, if compromised, could cause damage to national security and public safety.

Insiders aren’t just current employees. The classification extends to anyone with physical or digital access to sensitive areas, third-party vendors who understand your internal processes, and individuals who’ve developed deep institutional knowledge about how your organization operates.

Here’s the critical part: former employees, terminated contractors, and ex-partners remain insider threats long after they’ve left your organization. If they still possess organizational knowledge or retain any residual access, they represent ongoing security risks that many companies overlook.

What makes insiders so dangerous? Unlike external attackers, insiders operate from a position of trust with legitimate access. This allows them to sidestep traditional security controls designed to keep outsiders at bay. Their combination of trusted status and intimate knowledge of organizational vulnerabilities creates a perfect storm—they know exactly where your weak spots are and have the access to exploit them, whether intentionally or accidentally.

External threats are not considered insiders even if they bypass cybersecurity blocks and access internal network data. Any attack that originates from an untrusted, external, and unknown source is not considered an insider threat.

The days of blindly trusting users are over. A zero-trust network is the latest cybersecurity strategy, along with data loss prevention (DLP) solutions. These frameworks consider all users and internal applications as potential threats.

Insider threats often involve people who misuse their access to harm the organization’s critical information or systems. To mitigate this, understanding the behavior patterns and technical warning signs associated with them is essential.

Behaviors that typically signal insider threats:

• Frequently violates data protection and compliance rules
• Sudden changes in work habits, attitude, or performance
• Frequently engages in conflicts with employees or management
• Consistently receives low-performance reports or disciplinary actions
• Shows declining interest in projects or other job-related assignments
• Misuses travel and expenses or violates company resource policies
• Overly interested in projects that don’t involve them or attempts to access information outside their role
• Frequently uses sick leave or has irregular attendance
• Expresses dissatisfaction with the organization, management, or recent changes
• Works unusual hours for no good reason

These behavioral red flags may indicate the insider’s malicious intent or negligence.

Technical indicators can also help detect insider threats and data theft. Organizations typically monitor between 15 and 25 technical indicators, with the most effective programs focusing on these critical warning signs:

• Unusual data movement: Excessive spikes in data downloads, sending large amounts of data outside the company, and using tools like Airdrop to transfer files can be signs of an insider threat. Security teams should establish baseline data usage patterns to identify anomalies that exceed normal thresholds by 200% to 300%.
• Use of unsanctioned software and hardware: Negligent or malicious insiders may install unapproved tools to simplify data exfiltration or bypass security controls. This “shadow IT” creates security gaps and often precedes 45% of insider data theft incidents.
• Increased requests for escalated privileges or permissions: An individual requesting elevated access to sensitive information may be an insider threat from malicious intent or accidental exposure.
• Access to information unrelated to their job function: An employee who attempts to access data not relevant to their role.
• Renamed files with a file extension that doesn’t match the content: Malicious insiders may try to mask data exfiltration by renaming files to hide their actual content or use file compression and encryption tools.
• Abnormal access times outside regular business hours: Logins and activity at odd hours.
• Unusual logon activity accessing credentials, such as multiple sessions: Suspicious credential usage patterns, frequent password changes, or failed authentication attempts.
• Unknown locations accessing resources: Logins from unfamiliar locations.
• Excessive use of removable media or cloud storage services: Sudden increases in USB drive usage, personal cloud uploads, or attempts to bypass data loss prevention controls.
• Database query anomalies: Running unusual database queries, especially those targeting sensitive tables or extracting large datasets.
• Email and communication patterns: Forwarding sensitive emails to personal accounts, communicating with competitors, or encrypting files before sharing.

How Many Warning Signs Should Trigger Investigation?

Security experts recommend investigating when three or more behavioral indicators happen at once, or when any single high-risk technical indicator is detected. Organizations with mature insider threat programs typically set thresholds where 2-3 simultaneous technical anomalies trigger automated alerts, while 4-5 indicators prompt immediate investigation.

Technical indicators should be used with behavioral warning signs to identify potential insider threats and mitigate the associated risks.

Types of Insider Threats

Knowing how and why insider threats happen goes a long way in preventing data loss.

• Malicious insider threats: Individuals with authorized access who want to harm the organization. These insiders might sell sensitive data to rivals, intentionally leak confidential information, or sabotage company systems.
• Opportunistic insider threats: These employees don’t have bad intentions at first until opportunity knocks. They may hoard sensitive information and plan to exploit it when they leave or at another time for personal gain or vendetta.
• Negligent insider threats: These employees inadvertently compromise security through their disregard for protocols. Employees might bypass essential safeguards, unintentionally exposing critical assets without malicious intent.
• Accidental insider threats: Purely unintended incidents where insiders cause data breaches through mistakes—like sending files to incorrect recipients or misconfiguring databases. Just human error without any underlying motive.
• Compromised insider threats: Outside entities hijack legitimate users’ credentials via phishing scams or malware. Cyber criminals pretend to be real employees to gain unauthorized access and breach data security.
• Collusive threats: Insiders collaborate with external entities, such as competitors or cyber criminals, to conduct espionage, intellectual property theft, or gain unauthorized access. This collusion doubles down on the potential damage from insider knowledge and external resources and capabilities.

The diversity of these threats makes the case for a holistic approach to cybersecurity—one that transcends mere technological fixes and incident response plans. It highlights the critical role of fostering an organizational culture steeped in security awareness and vigilance at all levels.

Even the most successful and reputable companies are not immune to inside threats. Here are real-world examples of insider threats that have led to significant cybersecurity breaches:

• Rippling: In 2025, workforce management tech company Rippling filed a lawsuit against competitor Deel, alleging that Deel recruited a Rippling employee to act as a paid insider. The employee, who worked in Rippling’s Dublin office, allegedly accessed over 6,000 internal files over four months, including customer conversations and competitive intelligence.
• Coinbase: Cybercriminals successfully bribed customer support agents working for a third-party vendor to steal sensitive data from approximately 69,461 Coinbase customers. The attackers used social engineering to recruit rogue overseas support agents, gaining access to names, partial Social Security numbers, and other personal information.
• Desjardins: In 2019, Canada’s largest credit union required users to copy customer data to a shared drive that everyone could use. A malicious insider continued to copy this data for two years, resulting in 9.7 million publicly disclosed customer records. It cost Desjardins $108 million to mitigate the breach.
• General Electric: An engineer at General Electric, Jean Patrice Delia, stole over 8,000 sensitive files to start a rival company. The FBI investigated this incident, and Delia was sentenced to up to 87 months in prison.
• Texas Developer: In 2025, a software developer was convicted after implementing a kill switch sabotage plot, demonstrating how technical insiders can weaponize their system access for malicious purposes.
• Tesla: Two former Tesla employees misappropriated confidential information, including personal information of employees and production secrets, which was then leaked to a German news outlet.
• SunTrust Bank: A former SunTrust employee stole 1.5 million names, addresses, phone numbers, and account balances for bank customers. Other sensitive data was not accessed, but it posed a risk to the bank and its customers.
• Coca-Cola: An investigator found that a Coca-Cola employee copied the data of about 8,000 employees to a personal external hard drive. After Coca-Cola became aware of the data breach, the organization notified employees and offered free credit monitoring for a year.
• Pegasus Airlines: An employee’s negligence at Pegasus Airlines led to the exposure of 23 million files containing personal data due to the improper configuration of an AWS bucket. This incident exposed flight charts, navigation materials, and crew personal information.
• Cash App: A disgruntled employee leaked Cash App’s customer data. This case highlights the risk posed by employees who may act maliciously due to dissatisfaction or other personal motives.

Inside threats are a much different beast to tame. Organizations with an exceptional cybersecurity posture can still encounter data leaks and breaches with potentially catastrophic outcomes. Although challenging, recognizing indicators and detecting insider threats is critical for organizations with many employees, vendors, and contractors who have access to internal data.

While these terms sound similar, insider risk and insider threat represent fundamentally different security challenges that require distinct approaches.

Insider risk takes a broad, data-centric view of potential exposure events that could harm your company and stakeholders—regardless of whether someone intended to cause damage. Think of it as the umbrella covering all possible ways your data could be compromised through internal activities.

Insider threat, however, focuses specifically on the potential for someone with authorized access to intentionally or unintentionally harm your organization. This is about people and their actions, not just data vulnerabilities.

Why does this distinction matter? It completely changes how you build your security strategy.

Organizations that only focus on insider threats often miss the bigger picture. They overlook risks created by legitimate business activities, cloud migrations, and remote work environments. A comprehensive insider threat program must address both malicious actors and the everyday exposure risks that naturally arise from normal operations.

The bottom line: Understanding this difference helps security leaders allocate resources more effectively. Instead of just hunting for bad actors, you’re building defenses that protect against both intentional attacks and accidental data exposure—creating a more robust, realistic security posture.

Organizations must implement comprehensive strategies to detect and mitigate malicious insider threats, which can cause significant damage to the organization’s data and reputation. Here are some techniques and tools that can help in detecting and preventing malicious insider threats:

• Behavioral analytics: These tools analyze user behavior patterns to identify anomalies and detect potential insider threats. They can detect if an employee is suddenly accessing unusual files or systems, which may indicate malicious intent.
• Data loss prevention: DLP solutions monitor and protect sensitive data by identifying and preventing unauthorized access, transfer, or data leakage. They can help organizations enforce access controls and monitor data movements.
• Cybersecurity analytics and monitoring solutions: Cybersecurity analytics solutions that send alerts and notifications when users display suspicious activity to help organizations detect and respond to potential insider threats. These solutions also provide real-time visibility into user activities and data movements.
• User behavior analytics: UEBA tools analyze user behavior patterns to identify anomalies and detect potential insider threats. They can detect if an employee is suddenly accessing unusual files or systems, which may indicate malicious intent.
• Machine learning: ML models can be trained to identify insider threats by analyzing patterns of behavior associated with insider attacks. These models can help organizations detect and respond to potential threats more effectively.
• Threat hunting: Proactive threat hunting involves hunting for anomalous insider behavior that may not be detected by security controls alone. This can be done using techniques such as UEBA, ML, and human intelligence to identify potential threats.
• Insider threat management and security solutions: ITM software can help organizations detect and respond to insider threats by monitoring user activities and data movements, identifying abnormal behavior patterns, and automating responses to potential security incidents.
• Real-time monitoring: Tracking user activity and data movements in real-time can help organizations detect and respond to potential insider threats more effectively. This can be achieved using solutions that offer customizable alert thresholds to minimize false positives and real-time threat review capabilities.
• User feedback learning: Integrating user feedback to refine anomaly detection models can help organizations tailor their threat detection systems to specific organizational needs, improving the accuracy of their insider threat detection efforts.
• Kill chain detection: Employing cyber kill chain detection can help organizations uncover lateral malware movement or insider threat activities, identifying irregular behaviors and command-and-control (C&C) communication.

By implementing these techniques and tools, organizations can improve their ability to detect and respond to malicious insider threats, ultimately reducing the risk of data loss and system compromise.

Insider threats are uniquely difficult to stop because they exploit the one thing traditional security can’t protect against: legitimate access. Your firewalls and perimeter defenses are designed to keep outsiders out—but what happens when the threat is already inside?

The answer isn’t bigger walls or stronger passwords. It’s a fundamental shift from reactive incident response to proactive threat prevention. Since authorized users can bypass most traditional security controls, you need a completely different approach.

Here’s what works: a comprehensive prevention strategy that combines behavioral monitoring, smart policies, and the right security tools working together:

Build a Foundation for Prevention

• Establish a security policy: Assemble a proactive security policy that includes procedures for preventing, detecting, and stopping misuse by insiders. Consider including the consequences of potential insider threat activity and outline guidelines for investigating misuse. Your prevention strategy should clearly define acceptable use policies and create accountability frameworks that deter malicious behavior before it starts.
• Implement a threat detection governance program: Establish an ongoing, proactive threat prevention and detection program in collaboration with your leadership team. Ensure executives and key stakeholders are well informed on the scope of malicious code reviews, with privileged users treated as potential threats. Prevention works best when leadership champions the program and allocates sufficient resources for comprehensive monitoring.

Strengthen Access Controls and Infrastructure

• Secure your infrastructure: Restrict physical and logical access to critical infrastructure and sensitive information using strict access controls. Apply least privileged access policies to limit employee access and implement robust identity verification systems to prevent unauthorized access from the start. Zero-trust architecture principles work particularly well for insider threat prevention because they assume no user should be trusted by default.
• Set up strong authentication measures: Use multifactor authentication (MFA) and safe password practices to make it harder for attackers to steal credentials. Passwords should be complex and unique, and MFA helps prevent infiltrators from accessing your system even if they have user IDs and passwords. These authentication barriers create multiple prevention layers that stop both external attackers and compromised insiders.
• Eliminate idle accounts: Purge your directory of orphan and dormant accounts immediately and continuously monitor for unused accounts and privileges. Ensure that non-active users, such as former employees, can no longer access the system or the organization’s data. Account lifecycle management is critical for prevention because dormant accounts are easy targets for both malicious insiders and external attackers.

Implement Proactive Monitoring and Detection

• Map your exposure: Your organization’s CISO should analyze internal teams and map each employee’s likelihood of becoming a threat. This analysis shines a spotlight on potential risks and areas for preventive intervention. Risk mapping allows security teams to focus prevention efforts on the highest-risk individuals and access points.
• Use threat modeling: Apply threat modeling at scale to better understand your threat landscape, including threat vectors related to malicious code or vulnerabilities. Identify the types of roles that might compromise a system and how they might access your assets. Effective threat modeling helps organizations prevent attacks by anticipating how insiders might abuse their legitimate access.
• Investigate anomalous behavior: Investigate any unusual activity in your organization’s network to identify concerning employee behaviors early. Combined with behavior monitoring and analysis tools, you can efficiently identify and mitigate insider threats before they escalate into serious incidents. Behavioral analytics enable prevention by catching suspicious activities during the planning stages rather than after damage occurs.

Leverage Technology for Prevention

• Prevent data exfiltration: Place access controls and monitor access to data to prevent lateral movements and protect your organization’s intellectual property. Data loss prevention (DLP) tools work as the last line of defense, stopping sensitive information from leaving your environment even when other prevention measures fail.
• Implement insider threat detection tools: Use tools like Security Information and Event Management (SIEM) solutions, Endpoint Detection and Response (EDR), log management tools, User Behavior Analytics (UEBA), IT Management (ITM), and security automation to detect and prevent insider threats. Modern prevention platforms use machine learning to identify patterns that indicate potential insider risk before malicious actions occur.
• Leverage security automation: Implement security automation to understand baseline network behavior and react efficiently to different situations. Automated prevention systems can block suspicious activities in real-time while alerting security teams to investigate potential threats.

Foster Prevention Through Culture and Training

• Conduct sentiment analysis: Perform sentiment analysis to determine the feelings and intentions of individuals. Regular analysis can help you identify employees under stress, experiencing financial troubles, or performing poorly, enabling early intervention that prevents malicious behavior. Proactive employee support programs can address underlying issues that might otherwise lead to insider threats.
• Utilize employee awareness training: Use security awareness training to teach employees how to spot likely insider threat actors and make them aware of behavioral risk indicators. Prevention-focused training helps employees recognize and report concerning behaviors from colleagues while also educating them about their own responsibilities for protecting sensitive data.
• Conduct regular audits and reviews: Conduct regular audits and reviews of your security policies, procedures, and technologies to ensure they are up-to-date and effective in preventing and stopping insider threats. Continuous improvement of prevention strategies ensures your defenses evolve with changing threat landscapes and business requirements.

Successful insider threat prevention requires both technological solutions and human-centered approaches that address the root causes of malicious behavior. By implementing these prevention-focused solutions, organizations can improve their security posture to stop insider threats before they cause damage and protect their critical information and systems.

The rapid adoption of generative AI has fundamentally transformed the insider threat landscape, creating unprecedented security challenges for organizations worldwide. Current research from Axios reveals that over 4% of GenAI prompts and 20% of uploaded files exposed sensitive corporate data in Q2 2025, while 78% of knowledge workers now use third-party GenAI tools despite only one-third of organizations having defined AI usage guidelines. This explosive growth in unsanctioned AI usage, known as “shadow AI,” has expanded the traditional insider threat attack surface in ways that conventional security measures struggle to address.

Generative AI amplifies insider threat risks through multiple vectors that bypass existing security controls. Employees routinely input sensitive information into AI platforms like ChatGPT for productivity gains, unaware that this data can be stored in external databases or resurface in responses to other users. The CrowdStrike 2025 Threat Hunting Report documented how the DPRK-nexus adversary FAMOUS CHOLLIMA infiltrated over 320 companies in the last 12 months—a 220% year-over-year increase—by using generative AI at every stage of their employment process, from creating convincing resumes to using real-time deepfake technology during video interviews. Meanwhile, malicious insiders can leverage AI tools to automate sophisticated attacks that previously required advanced technical skills.

The detection challenge has intensified significantly. As AI agents become more autonomous and gain access to vast enterprise datasets, security leaders warn that organizations may begin trusting these systems implicitly, making them less likely to verify outputs and creating new blind spots in threat detection. The convergence of AI adoption and insider risk requires organizations to fundamentally rethink their approach to data protection and user behavior monitoring.

Proofpoint leads the cybersecurity industry with a people-centric approach that recognizes a fundamental truth: insider threats are ultimately about human behavior, not just technology.

Our insider threat management and data loss prevention solutions give organizations three critical capabilities they need to stay protected:

• Complete visibility into how users interact with sensitive data
• Operational efficiency through automated detection and response
• Rapid response capabilities that stop threats before they cause damage

Here’s how we tackle insider threats head-on:

Proofpoint Insider Threat Management (ITM) provides real-time, contextualized insights into user activity and behavior to detect and prevent insider threats. Key capabilities include:

• Visibility and prevention: ITM provides visibility into the “who, what, when, and where” of user actions, with timeline views and screen captures to aid investigations. It can also block users from exfiltrating data across channels like USB, web uploads, cloud sync, and print.
• Efficiency: ITM offers a centralized view to help security teams correlate alerts and manage investigations across endpoints, the web, cloud, and email. It includes workflows for better collaboration and exportable reports for HR, legal, and other stakeholders.
• Rapid time to value: ITM is a scalable, cloud-native solution that can be deployed quickly with a lightweight endpoint agent, providing flexible monitoring of both everyday and high-risk users.

Proofpoint Enterprise Data Loss Prevention (DLP) integrates with ITM to provide comprehensive protection against data loss from negligent, compromised, and malicious users. It can identify sensitive data, detect exfiltration attempts, and automate regulatory compliance.

Proofpoint Security Awareness Training helps transform employees into effective data defenders by proactively identifying potentially risky users and changing their behavior to ensure compliance.

To learn more about how to mitigate insider threats, contact Proofpoint.