[Blog](/blog) Show links Resources [Blog](/blog) [Breaches](/breaches) [eBooks, reports, & more](/resources) [Events](/events) [News](/news) [Attack Surface Management](/category/attack-surface-management) Show links Categories [Attack Surface Management](/category/attack-surface-management) [Company News](/category/company-news) [Compliance and Regulations](/category/compliance-and-regulations) [Cybersecurity](/category/cybersecurity) [Data Breaches](/category/data-breaches) [DevOps](/category/devops) [Human Cyber Risk](/category/human-cyber-risk) [Risks and Vulnerabilities](/category/risks-and-vulnerabilities) [Third-Party Risk Management](/category/third-party-risk-management) [Vendor Risk Management](/category/vendor-risk-management) [Insider Threats in Cyber Security: How to Detect & Prevent](/blog/insider-threat) Publish date March 23, 2025 {x} minute read # Insider Threats in Cyber Security: How to Detect & Prevent [Get a demo](/contact-sales) [Free trial](/demo) [Download the PDF guide](/resources/complete-guide-to-data-breaches) [Free trial](/demo) Written by [Abi Tyas Tunggal](/team/abi-tyas-tunggal) Writer and Senior Product Manager at UpGuard. Abi's work has influenced leaders across cybersecurity, technology, and financial services. Reviewed by [Kaushik Sen](/team/kaushik-sen) Chief Marketing Officer Kaushik has a background in software engineering, enterprise solution architecture, and data analytics. He brings a unique, data-driven perspective to cybersecurity education. Table of contents eBook A Complete Guide to Data Breaches Free resource ### A Complete Guide to Data Breaches Learn how to avoid a costly data breach with a comprehensive prevention strategy. [Download now](/resources/complete-guide-to-data-breaches) Insider threats, though the most difficult of cyber threats to identify, can be successfully mitigated with the right cyber risk management strategy. To learn how to reduce your risk of suffering a data breach from an insider threat, read on. ## What is an insider threat in cybersecurity? In cybersecurity, an insider threat is any individual that exploits their internal credentials to facilitate unauthorized access to private systems and data. Whenever access to internal systems is granted, that account has the potential to become an insider threat vector, making current employees, former employees, contractors, and even third-party vendors all potential insider threat actors. ## Why are insider threats dangerous? Insider threats are very difficult to identify. They often require legitimate access to an organization's sensitive resources, making[ roles-based access management](https://www.upguard.com/blog/rbac) ineffective. When an insider threat abuses their legitimate privileged access for malicious purposes, security teams struggle to filter out potentially suspicious activities, an issue likely driven by a[ lack of a baseline of normal user behavior.](https://www.ibm.com/account/reg/us-en/signup?formid=urx-39989) > Insider threat topped the list of most expensive initial attack vectors in 2024. The difficulty of identifying and managing insider threats makes this attack vector highly likely to cause a major cybersecurity incident, heightening its damage cost potential. According to the[ 2024 Cost of a Data Breach Report](https://www.ibm.com/reports/data-breach) by IBM and the Ponemon Institute, malicious insiders topped the list of the most costly initial attack vectors at an average of 4.99 million USD. > Insider threat detection is one of the most complicated aspects of a cybersecurity strategy. ## Insider threat examples Here’s a list of real-life insider threat examples. Note that not all insider threat activity involves account compromise. When these events are intentional, insider threats commonly leak internal data to the public. ### 2023 #### Tesla Data Leak Exposes 75,000 Employees Two former Tesla employees leaked sensitive personal information of over 75,000 current and former employees. [Read on Reuters](https://www.reuters.com/business/autos-transportation/tesla-says-two-ex-employees-behind-may-data-breach-2023-08-21/) ### 2022 #### Yahoo Employee Steals Trade Secrets A Yahoo research scientist downloaded proprietary information after receiving a job offer from a competitor. [Read on The Drum](https://www.thedrum.com/news/2022/05/19/yahoo-lawsuit-alleges-employee-stole-trade-secrets-upon-receiving-trade-desk-job) ### 2021 #### Proofpoint Executive Steals Confidential Data A former Proofpoint employee stole sales enablement data, including competitor battle cards, before joining a competitor. [Read on CRN](https://www.crn.com/news/security/proofpoint-alleges-ex-exec-took-trade-secrets-to-abnormal-security?itc=refresh) ### 2019 #### Capital One Data Breach Impacts 100 Million Individuals A former AWS engineer exploited insider knowledge to access Capital One servers, exposing sensitive data. [Read on Threatpost](https://threatpost.com/aws-arrest-data-breach-capital-one/146758/) ### 2018 #### Facebook Engineer Misuses Privileged Access A Facebook security engineer abused access to internal data to stalk women online. [Read on NBC News](https://www.nbcnews.com/tech/social-media/facebook-investigating-claim-engineer-used-access-stalk-women-n870526) ### 2016 #### Google Employee Steals Self-Driving Car Data A former Google employee downloaded thousands of files related to its self-driving car program before joining Uber. [Read on CNN](https://money.cnn.com/2017/02/23/technology/waymo-uber-google-lawsuit/?iid=EL) ## Types of insider threats in cybersecurity There are many different types of insider threats posing significant security risks to an organization; these include: * **Non-responders: **A small percentage of people are non-responders to security awareness training. While they may not intend to behave negligently, they're among the riskiest members since their behaviors fit consistent patterns. For example, individuals with a strong history of falling for phishing are likely to be phished again. * **Inadvertent insiders: **Negligence is the most common and most expensive type of insider threat. This group generally exhibits secure behavior and complies with [information security policies](https://www.upguard.com/blog/information-security-policy). Eventually, they make high-impact errors, like storing intellectual property on insecure personal devices. * **Insider collusion: **Although insider collaboration with malicious external threat actors is rare, it's still a significant threat due to the increasing frequency of cybercriminals recruiting employees via the [dark web](https://www.upguard.com/blog/dark-web). A study by the [Community Emergency Response Team (CERT)](https://insights.sei.cmu.edu/insider-threat/2016/06/the-frequency-and-impact-of-insider-collusion.html) found that insider-outsider collusion accounted for 16.75% of insider-caused security incidents. * **Persistent malicious insiders: **This type of insider threat most commonly attempts data exfiltration or other malicious acts, like installing [malware](https://www.upguard.com/blog/malware), for financial gain. A Gartner study on criminal insider threats found that 62 percent of insiders with malicious intent are people seeking supplemental income. * **Disgruntled employees: **Disgruntled employees may sabotage security tools and security controls or commit intellectual property theft. Behavior analytics could detect these types of insider threats by highlighting abnormal behavior patterns. For example, an employee may suddenly access sensitive data resources after being given a termination notice. * **Moles: **An outsider who has managed to gain insider access, usually by posing as an employee or partner. ## How to monitor for insider threats Monitoring for malicious insider threats is complex because it’s difficult to filter suspicious activity from permitted user activity when monitoring employees. However, the risk of insider attacks can be mitigated by focusing monitoring efforts across three primary human risk factors: * **Identity breaches: **When employee credentials are compromised in a data breach. * **Shadow IT: **Unauthorized use of apps and endpoints within an organization’s network. * **Third-party service data sharing:** Accepting weak internal data sharing permissions when signing up to third-party services, resulting in excessive exposure of sensitive internal information, like customer data. A common approach to addressing these insider threat indicators is to deploy a series of security measures for each type of insider cyber threat, such as security awareness training and phishing attack simulations. However, this approach fails to consider the relationships between these factors and how they impact each employee’s evolving cyber risk exposure in real-time. > A strategy comprising multiple insider threat security solutions causes unnecessary attack surface bloat. A more accurate and scalable approach is a holistic evaluation of all primary human cyber risk factors to produce a real-time score of each employee’s evolving risk exposure. Watch this video for an illustration of how User Risk by UpGuard solves this problem. [Get a free trial of UpGuard >](https://www.upguard.com/demo) ## How to detect insider threats CISOs and their security teams should monitor and detect common behaviors to stop active and potential insider threats. A good rule of thumb is to consider any abnormal activity as evidence of a likely insider threat. Additional indicators of potential insider threats should include: * Sudden negative changes in an employee's mode, such as when they start feeling dissatisfied or resentful. * When an employee suddenly starts performing more tasks requiring privileged access. ### Common indicators of insider threats The common indicators of compromise of insider threats can be split into digital and behavioral warning signs: #### Digital warning signs * Downloading or accessing unnatural amounts of data * Accessing sensitive data not associated with their job * Accessing data that is outside of their usual behavior * Making multiple requests for access to tools or resources not needed for their job * Using unauthorized external storage devices like USBs * Network crawling and searching for sensitive data * Data hoarding and copying files from sensitive folders * Emailing sensitive data to outside parties * Scanning for [open ports](https://www.upguard.com/blog/open-port) and [vulnerabilities](https://www.upguard.com/blog/vulnerability) * Logging in outside of usual hours #### Behavioral warning signs * Attempting to bypass [access control](https://www.upguard.com/blog/access-control) * Turning off [encryption](https://www.upguard.com/blog/encryption) * Failing to apply software patches * Frequently in the office during odd-hours * Displaying negative or disgruntled behavior towards colleagues * Violating corporate policies * Discussing resigning or new opportunities While human behavioral warnings can indicate potential issues, Security Information and Event Management (SIEM) or user behavior analytics tools are generally more efficient ways to detect insider threats as they can analyze and alert security teams when suspicious or anomalous activity has been detected ## How to prevent insider threats in 2025 There are several controls that can be implemented to reduce the risk of insider threats: * **Prioritize data protection:** Sensitive data is the primary target for insider threats. An effective insider threat program starts with mapping the flow of all your sensitive information and implementing tools to secure all potential points of access, such as encryption, and [Data Loss Prevention](https://www.upguard.com/blog/data-loss-prevention) (DLP)tools. Your data flow analysis will likely indicate sensitive information being shared with vendors, which will require a more focused third-party data protection approach offered in a[ Vendor Risk Management](https://www.upguard.com/blog/vendor-risk-management) program.   * **Protect critical assets: **Identify all of your critical assets storing sensitive information and make sure they remain secured with the latest patch updates. This will reduce the risk of security vulnerabilities only known to internal security teams from being exploited. * **Reduce your attack surface: **Maintaining a minimal attack surface will limit the potential attack vectors an insider threat could exploit to access sensiitve data and critical assets. This branch of cybersecurity is known as[ Attack Surface Management (ASM)](https://www.upguard.com/blog/attack-surface-management). * **Adopt behavioral analytics: **Artificial intelligence and behavioral analytics can help detect indiscernible anomalies in human behavior patterns that are likely indicators of a developing internal threat. In addition, user and entity behavior analytics (UEBA) can provide context that can be lost with manual review. * **Implement cybersecurity awareness training: **Equip staff to follow email best practices by teaching them how to detect and respond to email-based security threats , such as phishing cyberattacks. To further reduce the risk of email being used as an attack vector, ensure SPF, DKIM, and[ DMARC](https://www.upguard.com/blog/dmarc) are correctly configured * **Deploy phishing simulations: **Regularly test each employee's susceptibility to email scams with simulated phishing and social engineering attacks. * **Enforce MFA:** Enforce[ multi-factor authentication](https://www.upguard.com/blog/mfa-multi-factor-authentication) on endpoints as an additional security measure supporting awareness training. This control could be the safety net that blocks email scams employees mistake for legitimate correspondences. For this security measure to be most effective, staff should be trained never to disclose MFA codes via messaging apps. * **Conduct employee screenings:** Before hiring, screen employees with thorough background checks to flag risks like criminal history, significant debt, or other negligent insider red flags. Ongoing screenings or clearance reviews are recommended for roles requiring access to critical systems. * **Audit and review security policies regularly:** Frequently update your security policies to reflect changes, including employee screening procedures, incident response plans, and system vulnerability testing. * **Implement a human cyber risk solution: **Invest in a tool producing real-time ratings representing each employee's potential cyber impact on the organization, such as User Risk by UpGuard. eBook A Complete Guide to Data Breaches Free resource ### A Complete Guide to Data Breaches Learn how to avoid a costly data breach with a comprehensive prevention strategy. [Download now](/resources/complete-guide-to-data-breaches) ## Related posts Learn more about the latest issues in cybersecurity. Attack Surface Management #### [Find Out if You're Exposed on the Dark Web](/blog/find-out-if-youre-exposed-on-the-dark-web) Answer 5 quick questions to predict what a dark web scan will find about your company. Then run the free scan to see your real exposure. [](/team/lance-turner) [Lance Turner](#) October 14, 2026 Data Breaches #### [Your First Dark Web Scan Report, Explained](/blog/your-first-dark-web-scan-report-explained) You scanned your domain. What do the results mean? [](/team/lance-turner) [Lance Turner](#) October 13, 2026 Data Breaches #### [Good Security Rating? Your Dark Web Exposure Says Otherwise](/blog/good-security-rating-your-dark-web-exposure-says-otherwise) Scan your domain to see just how exposed you are on the Dark Web. [](/team/lance-turner) [Lance Turner](#) October 13, 2026 Attack Surface Management #### [Shadow MCP Servers: The AI Infrastructure You Can't See](/blog/shadow-mcp-servers) In 2012, it was Dropbox. In 2026, it’s Shadow MCP. Discover why unvetted AI agents are an invisible threat and how to regain total visibility. [](/team/shane-moosa) [Shane Moosa](#) August 25, 2026 Attack Surface Management #### [Six MCP Security Incidents Every Security Leader Should Know](/blog/mcp-security-incidents) From registry poisoning to filesystem wipes: discover the 6 MCP security incidents every leader must know to secure their AI agent workflows in 2026. [](/team/shane-moosa) [Shane Moosa](#) July 1, 2026 Attack Surface Management #### [1 in 15 MCP Servers are Lookalikes: Is Your Org at Risk?](/blog/mcp-server-lookalikes) For every official MCP server, up to 15 lookalikes exist. Learn to identify these registry-layer threats and discover methods to protect your organization. [](/team/shane-moosa) [Shane Moosa](#) May 12, 2026 [All posts](/blog) Experience superior visibility and a simpler approach to cyber risk management [Get a demo](/contact-sales) [Free trial](/demo)