Your company invested millions in firewalls and security software, but your greatest vulnerability sits at a desk inside your company and collects paychecks.
Employee-caused security breaches, whether through negligence, lack of training, or malicious intent, accounted for 62% of data breaches in 2025.
A single weak password or misclicked link can open the floodgates to data loss, financial damage, and reputational fallout. This massive blind spot costs businesses $4.99 million per incident.
In this blog, you’ll discover:
- 15 real-world examples of internal security slip-ups.
- The reasons why the breaches occurred.
- Practical ways to stop them before they happen to your organization.
What is behind cyberattacks involving employees?
When we think about cyberattacks, we picture the stereotypical hacker: hoodies, dark rooms, and lines of code flashing across the screen.
But the reality is much more mundane. Most data breaches don’t happen due to sophisticated attacks. They start with simple, everyday employee mistakes.
The numbers back this up:
- Your employees start most breaches: 62% of security breaches involve some form of human error, whether it’s clicking a spear phishing link or a social engineering scam. Even with the best firewalls and software, a single lapse in judgment can compromise an entire system.
- Almost every breach involves people: Up to 95% of security issues involve some human element, and nearly half of all cybersecurity breaches come from inside your organization, whether by accident or on purpose.
- Cloud systems aren’t immune: Even within cloud environments, employees cause problems; 55% of cloud data breaches come from human error. This shows that even your advanced systems are only as secure as the people who run them.
- We underestimate the human factor: While many companies know human error is a threat, they don't realize how big it is. Only 22% of organizations name it as their top concern, despite it playing a role in most breaches. This gap between what we believe and what actually happens creates a dangerous blind spot.
- Scam emails still work too well: Email scams are still extremely effective and cause 15% of breaches. This shows just how well social engineering works and why your team needs better training.
- Employees are still falling for phishing emails: Despite all the warnings, 33% of employees still fall for phishing emails at work.
- Email mistakes leak data: Simple errors like sending sensitive information to the wrong person cause significant data leaks, with 17% of employees admitting they've done this. It points to the need for stronger email protection and better data handling rules.
- These mistakes cost you customers: These statistics translate to real losses, with 29% of companies losing customers because of employee email errors. This is just one example of the immense damage that can be inflicted on a company's reputation and bottom line.
- Younger staff fall for scams more often: Surprisingly, younger employees are five times more likely to be tricked by phishing attempts. You need to tailor your security training to different age groups and remember that “digital-first generations” aren't scam-proof.
Remember that most of these human errors directly connect to insider threats. Whether it's accidental data leaks, clicking on phishing links, or deliberate malicious actions, your employees often create your biggest security risks. And if you want to stop breaches before they happen, you need to spot the warning signs.
What types of data security breaches are caused by employees?
Now that we’ve seen how often human error is involved in breaches, let’s examine what those breaches look like.
Employee-related security incidents take many forms, from accidental data leaks to malicious insider attacks. Understanding the types can help you spot the signs and take action before things escalate.
Malicious insider threats (Intentional harm)
Malicious insider threats happen when employees deliberately use their access privileges to harm the organization. These individuals use their legitimate access and knowledge of security measures to intentionally damage the company, steal information, or benefit personally.
They know exactly where the weak points are and how to exploit them, which makes them especially dangerous and hard to detect.
Here are some common examples of malicious insider threats:
- Data theft: Employees steal proprietary information, customer databases, or intellectual property to sell to competitors or on the dark web. A departing sales executive might download the entire customer database before joining a rival company.
- System sabotage: Disgruntled workers deliberately damage systems, delete critical data, or insert malicious code. An IT administrator might plant time-delayed malware designed to corrupt backups weeks after they've left the company.
- Financial fraud: Staff with access to financial systems manipulate transactions, create fake vendors, or embezzle funds. A finance team member might create ghost employees in the payroll system to move salary payments to personal accounts.
- Intellectual property leaks: A staff member shares trade secrets, proprietary code, or confidential product plans with outside parties, sometimes for a payout, other times for recognition.
- Corporate espionage: Insiders may work with external entities (such as competitors, nation-states, or cybercriminal groups) to feed them sensitive business or security information.
- Privacy violations: Staff access and expose sensitive personal data about customers or fellow employees for harassment, stalking, or personal gain. A worker might look up and leak the medical records of a celebrity patient to tabloid media, creating a healthcare insider risk.
Negligent insider threats (Unintentional mistakes)
Negligent or unintentional insider threats come from employees who make careless mistakes or ignore security protocols without malicious intentions. These accidental breaches happen when well-meaning staff take shortcuts, don't understand policies, or fail to spot security risks in their daily work.
Though not deliberate, these errors can cause damage just as serious as planned attacks and often make up the most common type of insider threat.
Here are some common examples of negligent insider threats:
- Misdirected emails: An employee accidentally shares sensitive files with the wrong recipient, uploads them to unsecured platforms, or forgets to encrypt them before sending.
- Phishing victims: Staff members fall for convincing scam emails, click malicious links, or provide credentials to fake websites that appear legitimate.
- Password mismanagement: Employees use weak passwords, reuse the same credentials across multiple services, or share login information with colleagues.
- Device misplacement: Staff lose laptops, smartphones, or other devices containing sensitive data without proper encryption or remote wipe options.
- Improper data handling: Employees store confidential information on unsecured personal devices or unsanctioned cloud services. A remote worker may upload sensitive client files to their personal Dropbox, bypassing company-approved file sharing.
- Misconfigured systems: A non-technical employee may inadvertently change settings in cloud tools or collaboration software and expose sensitive information to the public.
- Shadow AI usage: Employees use unauthorized AI tools and browser extensions for work tasks without company approval. In so doing, they bypass enterprise security controls and introduce unknown vulnerabilities.
- AI prompt data leakage: Staff members inadvertently paste proprietary source code, confidential financial data, trade secrets, or customer PII into public AI chatbots (to help summarize text, write code, or draft emails). This type of AI data leakage can expose sensitive data to external servers and training models.
What are some real-world examples of security breaches caused by employees?
To see how these insider threats play out in real life, here are 15 real-world examples of security breaches caused by employees, some accidental, others intentional, and all avoidable.
Each of these insider threat examples offers a valuable lesson in what can go wrong and how to prevent it.
1. Tesla insider data theft (2021)
What happened: In early 2021, Tesla faced a major security breach when a new engineer allegedly stole about 26,000 sensitive files just days after joining the company. Tesla discovered this when it caught the employee downloading confidential data during his first week.
Type of attack: Malicious insider theft of intellectual property through unauthorized data exfiltration. The stolen files contained proprietary software code related to Tesla's back-end business management systems and automation processes for manufacturing operations.
Consequences: The impact was serious, though Tesla didn't reveal exact financial losses. The stolen data threatened to expose Tesla's competitive edge in the electric vehicle market, and the incident hurt trust in the company's hiring and security practices.
Key lesson: This incident shows the importance of monitoring new employees and limiting access privileges during probationary periods, especially for technical roles with access to proprietary source code and intellectual property.
2. Equifax data breach (2017)
What happened: Approximately 147 million people had their personal information exposed when Equifax, a leading credit reporting agency, suffered a major data breach in 2017. Despite the Apache Software Foundation issuing a security patch in March 2017, Equifax employees didn't apply this update to their systems. The oversight created an opening that hackers exploited for over two months before the breach was detected.
Type of attack: Exploitation of an unpatched vulnerability in the Apache Struts web application framework.
Consequences: The attackers broke into the network and stole sensitive data like Social Security numbers and credit card details. The consequences were severe; Equifax faced a $575 million settlement with the FTC, CFPB, and 50 U.S. states, while its stock price plummeted over 30% after the announcement.
Key lesson: Install security patches on time and train your employees thoroughly to prevent devastating breaches like this one.
3. Morrisons internal data leak (2014)
What happened: In March 2014, UK supermarket chain Morrisons suffered a major data breach when a disgruntled employee leaked the payroll data of nearly 100,000 staff members. The employee, who had authorized access, copied the data onto a personal USB drive and uploaded it to a file-sharing website, also distributing it to several newspapers.
Type of attack: Insider threat (malicious insider with authorized access).
Consequences: Names, addresses, bank account details, and salary information were exposed. Morrisons spent millions responding to the breach and protecting affected employees from fraud and identity theft.
Key lesson: Even trusted employees can pose a risk. Implement strict access controls, user activity monitoring, and insider threat detection to protect sensitive data.
4. Snapchat insider data leak (2016)
What happened: In 2016, Snapchat experienced a data breach that exposed the payroll information of around 700 current and former employees. A high-ranking payroll employee was tricked by an email impersonating CEO Evan Spiegel and unknowingly sent sensitive data.
Type of attack: Social engineering (CEO impersonation/phishing).
Consequences: Names, Social Security numbers, wage information, and other personal details were leaked. While the financial impact wasn't publicly disclosed, the incident caused embarrassment for a technology company that promotes privacy and security as core features of its platform.
Key lesson: Even sophisticated tech companies can fall victim to social engineering, which shows how important strong employee training and phishing detection systems are.
5. UPMC data breach (2014)
What happened: In February 2014, the University of Pittsburgh Medical Center (UPMC), a major healthcare provider, announced a data breach that exposed the personal information of about 66,000 employees. The breach was due to a hacker who broke into UPMC's human resources database using his knowledge of Oracle PeopleSoft software. From 2013 to 2014, they stole sensitive data (including names, Social Security numbers, addresses, salaries, and bank details) and sold it on the dark web.
Type of attack: Targeted database hack exploiting vulnerabilities in HR management software (Oracle PeopleSoft).
Consequences: Criminals used this information to file hundreds of fake tax returns, stealing $1.7 million in refunds, which they converted to Amazon gift cards and shipped to Venezuela. UPMC paid $2.65 million in a settlement to affected employees after they filed a class-action lawsuit.
Key lesson: Organizations need stronger security measures for systems that contain sensitive employee data, especially widely-used enterprise software with known vulnerabilities. Regular security audits, prompt patching, and employee monitoring for unusual database access or activity patterns are vital.
6. Capital One data breach (2019)
What happened: In July 2019, Capital One announced a massive data breach that exposed the personal information of over 100 million customers and applicants. The breach happened because of a poorly configured cloud server and was carried out by someone who used to work for Amazon Web Services (AWS), Capital One's cloud provider.
Type of attack: Cloud infrastructure misconfiguration exploit by a knowledgeable former insider.
Consequences: The breach cost Capital One $80 million in fines, and they spent another $100-$150 million on notifications, monitoring, and legal fees. The breach affected over 1 million Canadian and 100 million U.S. customers, which hurt the bank's reputation for data security.
Key lesson: Companies need to set up proper security configurations when migrating to cloud environments. This includes access controls, following cloud security best practices, and regularly auditing cloud infrastructure for any weaknesses.
7. Deep Root Analytics data breach (2017)
What happened: In June 2017, Deep Root Analytics, a data firm working for the Republican National Committee (RNC), exposed the personal details of about 198 million U.S. voters, almost every registered voter in the country. Cybersecurity researchers found the data sitting unsecured on an Amazon S3 cloud server, where it had been open to anyone for nearly two weeks. The breach happened because someone incorrectly set up the server, leaving 1.1 terabytes of data accessible without a password.
Type of attack: Misconfiguration vulnerability (unsecured cloud storage). Not an active attack but an exposure due to a security error.
Consequences: This data included names, addresses, birth dates, phone numbers, and voter profiling information. The breach had major consequences, though no one confirmed immediate financial losses. Voters filed a class-action lawsuit claiming negligence, seeking over $5 million in damages, and many worried about identity theft and election manipulation.
Key lesson: Cloud misconfigurations can expose massive datasets. Always secure cloud storage with proper permissions, authentication, and regular audits.
8. Ubiquiti Networks data breach (2021)
What happened: In January 2021, networking equipment manufacturer Ubiquiti Networks disclosed a data breach that potentially exposed customer account credentials. Initially reported as an external cloud provider breach, the incident later took a dramatic turn when the true nature of the attack was revealed. The breach was orchestrated by a senior IT employee at Ubiquiti who had access to the company's Amazon Web Services (AWS) and GitHub accounts.
Type of attack: Malicious insider threat combined with an extortion attempt.
Consequences: The breach caused Ubiquiti's stock price to drop by approximately 20%, temporarily wiping out nearly $4 billion in market value. Plus, the company faced major reputational damage when customers lost confidence in their security practices.
Key lesson: Internal threats can be just as dangerous as external ones. Set up least privilege access, monitor employee activity, and keep an eye on internal security controls.
9. Twitter insider case (2020)
What happened: In July 2020, Twitter faced a major breach when hackers took over the accounts of famous people like Barack Obama, Elon Musk, and Jeff Bezos to promote a Bitcoin scam. The attack was led by a 17-year-old hacker who worked with others and got into Twitter's systems via an employee. The breach happened when he pretended to be an IT worker and used a clever phone scam to trick Twitter staff. He convinced an employee to give him access to an internal admin panel.
Type of attack: Social engineering/vishing (voice phishing) attack that led to unauthorized access to internal administrative tools.
Consequences: The scam collected over $118,000 in Bitcoin within hours as people sent money to a fake address that promised to double their investment. Twitter's reputation suffered as the breach showed weaknesses in how the company controlled employee access, though they didn't report direct financial losses apart from the costs of responding to the attack.
Key lesson: Even a single compromised employee can lead to platform-wide breaches. Invest in strong access controls, employee verification protocols, and continuous security awareness training.
10. Pegasus Airlines data exposure (2022)
What happened: In February 2022, Pegasus Airlines experienced a major data breach when an employee misconfigured an AWS storage bucket, leaving it publicly accessible. As a result, the personal data of around 6.5 million passengers, including names, email addresses, phone numbers, passport details, and flight information, was exposed online.
Type of breach: Accidental data exposure due to misconfigured cloud storage.
Consequences: While there was no confirmed data misuse, the breach posed serious risks to flight safety and crew privacy. Pegasus Airlines faced potential financial penalties, including a possible $183,000 fine from Turkey’s data protection authority for violating privacy regulations.
Key lesson: Cloud security missteps can expose massive volumes of sensitive data, so make sure to always secure storage buckets with proper authentication.
11. Cash App customer data leak (2022)
What happened: In April 2022, Cash App announced a data breach that exposed the personal information of about 8.2 million current and former U.S. customers. The breach occurred when a former employee, after being fired, accessed and downloaded internal reports with customer data. This person had access to the reports, which contained full names, brokerage account numbers, and for some customers, portfolio values, holdings, and stock trading activity.
Type of attack: Post-termination unauthorized access by a former employee (improper offboarding).
Consequences: Although no passwords or Social Security numbers were stolen, the exposed data increased the risks of targeted phishing attacks or fraud attempts. The company settled a lawsuit in 2024 for $15 million, and the incident greatly damaged Cash App's security reputation.
Key lesson: Revoke access immediately when someone leaves your organization. Delayed deactivation of credentials can lead to serious employee fraud.
12. Yahoo intellectual property theft (2022)
What happened: In May 2022, Yahoo filed a lawsuit against a former engineering director for allegedly stealing proprietary technology before leaving the company. The case involved the theft of intellectual property related to Yahoo's advertising systems, which formed a core part of the company's revenue stream. According to the lawsuit, the employee downloaded thousands of confidential files, including source code, technical documentation, and business strategies related to Yahoo's advertising technology platform.
Type of attack: Intellectual property theft by an insider (trade secret misappropriation).
Consequences: The theft threatened Yahoo's competitive advantage, as the stolen AdLearn data could give competitors an unfair edge, though they didn't publicly state exact financial losses.
Key lesson: Protecting intellectual property is just as important as securing customer data. Monitor employee access to sensitive assets and set up strict data exfiltration controls during offboarding.
13. South Georgia Medical Center (SGMC) data theft (2021)
What happened: In February 2021, South Georgia Medical Center (SGMC) discovered that a former employee had stolen the protected health information of over 39,000 patients during their employment at the hospital. The investigation revealed that the employee had been systematically accessing and downloading patient files over an extended period.
Type of attack: Insider data theft of protected health information (PHI).
Consequences: The stolen data included patients' names, addresses, dates of birth, medical record numbers, and limited treatment information. SGMC didn't report any financial losses and found no evidence that anyone misused the data, though affected patients faced possible privacy risks.
Key lesson: In healthcare especially, continuous monitoring of employee access to PHI is critical.
14. Mailchimp data breach (2022)
What happened: In April 2022, Mailchimp suffered a security breach that exposed data from more than 100 client accounts, including cryptocurrency companies and financial services providers. The incident raised concerns about supply chain attacks for multiple organizations through a single service provider. The breach happened when attackers used social engineering to trick Mailchimp employees into giving up their login credentials.
Type of attack: Social engineering attack that led to credential theft and unauthorized access to customer accounts.
Consequences: The breach affected many of Mailchimp's clients, though the company didn't report direct financial losses. However, affected customers faced increased phishing risks. Mailchimp paid for response costs and suffered reputation damage.
Key lesson: Third-party vendors can be a weak link, so invest in employee training and enforce multi-factor authentication to reduce the risk of social engineering breaches.
15. Slack code repositories theft (2022)
What happened: In December 2022, Slack disclosed a security breach involving the theft of private code repositories. The company announced that an unauthorized party gained access to its GitHub repositories through stolen employee tokens. The breach happened when an unknown attacker stole a small number of Slack employee tokens and used them to gain unauthorized access to GitHub repositories hosted outside Slack's systems.
Type of attack: Token theft leading to unauthorized access to development resources.
Consequences: The damage seemed limited, with no direct financial losses or customer data breaches reported. However, people criticized Slack for adding a "noindex" tag to its information security notice in some regions, which prevented it from appearing in search engines and raised questions about transparency.
Key lesson: Protect developer credentials and access to code repositories. Use token rotation, MFA, and clear incident disclosure practices.
How do you prevent security breaches caused by employees?
Preventing employee-caused breaches takes more than just good intentions. You need a layered strategy that combines training, technology, and clear processes.
Below are six proven best practices to help you build a more secure organization from the inside out:
Limit access to what employees actually need
Give employees only the minimum permissions they need to do their jobs, and nothing more than that. This simple rule limits damage when accounts are compromised and prevents staff from seeing sensitive data they shouldn't access.
You must also regularly review access. When someone changes roles or leaves the company, immediately update or remove their access to close potential security gaps.
Add an extra layer of protection with Privileged Access Management (PAM) tools. These solutions secure your most critical systems by creating controlled access paths with features like temporary credentials and activity recordings.
Train your employees to spot threats
Teach your employees to recognize phishing scams, social engineering tactics, and other common attack methods. Make the training relevant to their job roles so team members understand the risks specific to their department.
You should also create security awareness programs that run throughout the year. For example, send periodic security updates, run simulated phishing exercises, and share examples of recent breaches to build good habits.
Monitor user activity and behavior
User activity monitoring (UAM) tools track employee actions across systems and flag suspicious behavior in real-time, such as unusual login times, large file transfers, or unauthorized access to sensitive files.
In addition, data loss prevention (DLP) tools help stop sensitive information from being shared or leaked, whether by accident or on purpose. When combined with real-time alerts for policy violations or unusual user behavior, organizations can take quick action to mitigate risks.
Strengthen your technical security measures
Set up systems that automatically spot, test, and deploy patches across your company as soon as they're released. It’s also a good idea to create prioritization rules to handle the most important security patches first, especially for internet-facing systems and widely used applications.
Use strong authentication methods like multi-factor authentication for all accounts, especially those with access to key systems. These controls create safety nets that prevent security incidents even when human errors occur.
Set clear onboarding and offboarding procedures
Thorough onboarding sets the security tone from day one. New employees should learn your security policies, receive proper access levels, and understand their responsibilities before they start handling sensitive information.
You must also develop robust offboarding protocols, such as removing access when employees leave the organization. You need to collect company devices, disable accounts, and revoke credentials immediately during an employee's departure process.
Create a security-conscious culture
Technical tools and policies only go so far if the broader company culture doesn’t support them. Leadership needs to set the tone by making security a visible, everyday priority. When executives follow best practices, regularly communicate risks, and take part in training themselves, it sends a clear message that security is everyone’s responsibility.
Reward teams that follow best practices, share success stories in internal communications, and include security achievements in performance reviews. When security becomes part of how a company measures success, employees will naturally integrate it into their daily work routine.
How does Teramind prevent insider-related security breaches?
Preventing the costly human errors and malicious insider threats outlined above requires more than just standard firewalls; it requires deep visibility and proactive controls.
Teramind combines workforce productivity analytics, insider risk management, and endpoint Data Loss Prevention (DLP) into a single, all-in-one unified architecture that stops internal breaches before they happen.
Here is how Teramind protects your organization from the inside out:
- 360-degree endpoint visibility: Teramind provides multi-channel endpoint visibility to capture and analyze user activity across more than 15 system channels, including desktop screens, emails, USB drives, websites, and applications. It also allows administrators to view employee desktop screens in real-time or replay historical video recordings to gain full forensic context around user activities.
- Proactive real-time intervention: Moving beyond passive alerting, Teramind takes direct action the moment an employee violates a security policy. You can configure smart rules and automated responses to issue user coaching warnings, automatically block policy violations, or instantly lock and terminate compromised endpoint sessions.
- Advanced Data Loss Prevention (DLP): Teramind’s DLP tools inspect, detect, and block unauthorized data movement across USB drives, cloud storage services, web uploads, and email attachments. Its patented Optical Character Recognition (OCR) engine extracts and searches text embedded directly within live screens and applications, enabling automated policy enforcement based on visual on-screen content.
- Intelligent User & Entity Behavior Analytics (UEBA): Teramind builds individual behavioral baselines over time to detect genuine anomalies, such as gradual data exfiltration or unusual command velocity. The platform automatically calculates and ranks risk scores for individual users and departments based on these behavioral deviations.
- Shadow AI governance: Teramind’s AI DLP extends endpoint-level visibility to detect and control unsanctioned AI tools and agents. This capability inspects and blocks employees from sharing sensitive data with platforms like ChatGPT, Claude, and Gemini.
- Forensic-grade evidence: Teramind captures screen recordings and activity logs as legally admissible, chain-of-custody evidence. This gives HR, legal, and investigation teams a defensible forensic record to understand exactly how an incident unfolded.
Ready to eliminate your biggest security blind spots?
