What is a Data Breach: How It Happens, Examples, and Best Practices to Prevent It

Quick Summary: Want to know what a data breach is and how it can impact your organization? This blog will help you understand what a data breach is and how it occurs in the simplest way possible. Get a complete understanding with examples of real-world cases. Keep reading for more!

Today, data is critical for every organization and as valuable as gold. It plays an important role in all aspects of the business including decision-making, operational efficiency, and employee management. However, with the growing threats of cyber incidents, securing your data is a hard nut to crack.

Data breaches occur when your confidential information is leaked. Plus, the data is available to a third party that you have not permitted to access it. Isn’t it frightening? Your business-critical information is in the hands of someone you don’t know and trust.

There are many drastic consequences of this situation when your data is exposed, like you can lose your business secrets and user trust as well. Preventing data breaches is the best measure to protect your sensitive data.

You can start by identifying weaknesses in your existing systems or applications to know what needs to be fixed. And to do that, you can use pentesting tools that uncover potential weaknesses and help you with remediation guidance.

In this blog, we’ll understand what exactly a data breach is, how it happens, and examples of some major real-world breaches. Plus, we’ll cover the best practices you can follow to prevent data breaches and how ZeroThreat’s AI-driven pentest tool can help you automate security with ease. With that said, let’s get started.

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What is Data Breach?

A data breach is a security incident in which sensitive, confidential, or protected information is accessed, exposed, stolen, or disclosed without authorization. It can affect personal data, financial records, login credentials, intellectual property, or business information. Data breaches often result from cyberattacks, security vulnerabilities, human errors, or misconfigured systems that expose valuable data.

A simple example is an online shopping website with an unpatched security flaw. An attacker exploits the vulnerability to access the customer database and steals names, email addresses, passwords, and payment details. Although customers did not willingly share this information, it became exposed because the organization's security controls failed to prevent unauthorized access.

Common types of data stolen in a data breach includes:

• Personal information (PII)
• Financial data
• Login credentials
• Healthcare records
• Intellectual property
• Business-sensitive information

A recent example is the Marks & Spencer data breach in 2025, where a cyberattack disrupted business operations and compromised customer information. The incident highlighted how attackers can exploit weaknesses in enterprise systems, causing financial losses, operational disruption, and reputational damage. It also reinforced the need for continuous security testing, timely patching, and proactive threat detection.

How Does Data Breach Happen?

A data breach happens when a gap in security, whether human, technical, or procedural, gives attackers or insiders a way to access data that should stay protected.

Internal Factors

Internal factors are security gaps that exist within an organization's people, processes, or technology. While often unintentional, these issues can create opportunities for unauthorized access and data exposure.

• Human error: Employees may accidentally share sensitive files, send information to the wrong recipient, or misconfigure systems, exposing confidential data without realizing the security impact.
• Weak access controls: Excessive user privileges, poor identity management, and failure to follow the principle of least privilege can allow unauthorized users to access sensitive business data.
• Unpatched software: Delaying security updates leaves known vulnerabilities unaddressed, making internal systems, web applications, and servers easier targets for attackers seeking unauthorized access.
• Cloud misconfigurations: Incorrect security settings in cloud storage, databases, or infrastructure can unintentionally expose sensitive information to the internet without requiring sophisticated attack techniques.
• Insider threats: Current or former employees, contractors, or trusted partners may intentionally or unintentionally misuse their legitimate access, resulting in data theft, leakage, or unauthorized disclosure.

External Factors

External factors involve threats originating outside the organization. Cybercriminals often combine multiple attack techniques to exploit vulnerabilities, bypass security controls, and compromise valuable data.

• Phishing attacks: Attackers use fraudulent emails, messages, or fake websites to steal login credentials, deploy malware, or trick employees into revealing confidential information.
• Ransomware attacks: Malicious software encrypts critical systems and often steals sensitive data before demanding payment, increasing both operational disruption and the risk of data exposure.
• Exploited application vulnerabilities: Attackers actively target unpatched web applications and APIs, exploiting security flaws such as SQL injection, authentication bypass, or remote code execution.
• Credential attacks: Stolen, reused, or leaked passwords enable attackers to gain unauthorized access through credential stuffing, password spraying, or brute-force login attempts.
• Third-party vendor compromises: Weak security within suppliers, software providers, or business partners can become an entry point for attackers to access connected systems and sensitive information.
• Malware infections: Trojans, spyware, keyloggers, and other malicious software can silently collect credentials, monitor user activity, and exfiltrate confidential data from compromised devices.
• Advanced persistent threats (APTs): Highly skilled attackers establish long-term access to enterprise environments, moving laterally across systems to steal sensitive information while avoiding detection for extended periods.

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Some Notable Examples of Data Breaches

Many organizations around the world have suffered security breaches to date resulting in compromised data. Even organizations with great reputations have gone through this situation. Below are a few examples of such organizations that have faced data breaches in the past.

• Yahoo!: Yahoo faced one of the biggest data breaches in history that compromised the personal information and passwords of users. Billions of users were affected by this incident. The breach was reported in 2016.
• Microsoft: In 2021, the Microsoft Exchange email server was attacked by hackers who provided access to around 60,000 emails of companies.
• Global Affairs Canada: Recently in 2023, hackers breached the security of Global Affairs Canada’s VPN resulting in accessing the personal information of users and employees. The hackers got access to personal information such as emails and contacts with this attack.

Should You Care About Data Breaches?

Why not? A single incident of data breach will cost you the reputation you have earned to date and incur heavy financial penalties and losses. Besides, data breaches can expose your data to a bad actor who can either sell it on the dark web or exploit it for a bigger attack.

Bad actors can use your data to commit crimes with deepfakes, steal your identity, blackmail you, and get involved in other nefarious activities. The following are the risks of data breaches.

Damaged Reputation

Your customers trust you, that’s why they are using your applications. In case of a data breach, their trust will be gone, and it will be hard to gain that confidence again. As a result, it will destroy your reputation affecting your market value, profit, and future growth. Not only will it be hard to gain new customers, but retaining the existing ones will be a bigger challenge.

Regulatory Actions

Organizations must comply with many data protection standards and laws such as HIPAA, CCPA, PCI DSS, GDPR, SOC2, ISO, and more. HIPAA and PCI DSS are specifically important for organizations operating in the financial and healthcare sectors.

These regulations and standards are important to ensure the data protection of an organization’s customers. Many of these regulations require strict penalties in case of a data breach. For example, under the GDPR (General Data Protection Regulation) law, organizations have to pay up to 4% of their annual turnover in case of a data breach.

Financial Loss

Data breaches can cost significantly to your organization and cause heavy financial loss. Indeed, IBM’s report on data breaches states that the average cost (global) of a data breach is 4.88 million USD. This shows that organizations are losing millions of dollars every year due to exposed data.

How to Prevent Data Breaches (Best Practices)

Preventing data breaches requires a proactive, multi-layered defensive strategy that combines continuous security testing with strict access governance. Organizations that are serious about security must validate their exploit paths to neutralize threats before attackers find them.

Here are some of the best practices to follow for preventing data breaches:

Implement Zero Trust Architecture

Never trust, always verify. Restrict lateral movement within your network by verifying every user and device attempt to access corporate assets. Implement strict network segmentation and require continuous identity authentication at every security perimeter.

Adopt Robust API Security Testing

Deploy automated application security testing to identify logic flaws like Broken Object Level Authorization (BOLA). Regular exploit validation ensures that backend APIs cannot be manipulated to expose database objects to unauthorized users.

Enforce Multi-Factor Authentication (MFA)

Mandate phishing-resistant multi-factor authentication across all enterprise applications, VPNs, and cloud portals. This simple control blocks credential stuffing attacks, preventing threat actors from gaining access even if they steal corporate passwords.

Conduct Continuous Vulnerability Testing

Scan your public attack surface continuously using advanced dynamic application security testing (DAST) tools. Prioritize remediation based on proven exploitability rather than long, unvalidated vulnerability lists to fix critical security gaps quickly.

Secure Cloud Configurations

Audit cloud storage repositories and buckets regularly to eliminate misconfigurations. Ensure all data storage environments enforce strict access control lists, disable public read access by default, and log all data access attempts.

Train Employees on Phishing Defense

Run regular, simulated phishing campaigns to educate employees on how to spot sophisticated social engineering tactics. Building security awareness helps workers recognize corporate credential harvesting attempts, reducing the risk of initial perimeter access.

Enforce Principle of Least Privilege

Restrict user access rights to the absolute minimum necessary for their job functions. Conduct frequent access reviews to eliminate privilege creep, ensuring that compromised accounts cannot exfiltrate vast amounts of sensitive corporate data.

How ZeroThreat Helps Prevent Data Breaches

Preventing data breaches starts with identifying and eliminating exploitable security weaknesses before attackers can abuse them. ZeroThreat continuously discovers, validates, and helps remediate risks across web applications and APIs, enabling organizations to strengthen their overall security posture.

Step 1: Discover Your Complete Attack Surface

ZeroThreat automatically discovers internet-facing web applications, APIs, authenticated workflows, and exposed assets. It also identifies shadow APIs and undocumented endpoints, giving security teams a complete view of potential attack surfaces that could expose sensitive data.

Step 2: Perform Context-Aware Security Testing

Instead of relying on static signature matching, ZeroThreat analyzes application behavior and executes context-aware security testing. It evaluates authentication, authorization, business logic, and application workflows to uncover vulnerabilities that traditional scanners often miss.

Step 3: Validate Real Exploitability

After identifying potential vulnerabilities, ZeroThreat safely validates whether they can actually be exploited. This exploitability-first approach confirms real attack paths and significantly reduces false positives, allowing security teams to focus on issues that present genuine business risk.

Step 4: Prioritize Risks Based on Impact

ZeroThreat prioritizes validated findings according to exploitability and potential business impact rather than relying solely on severity scores. This helps security and development teams remediate the most critical vulnerabilities first and reduce overall exposure faster.

Step 5: Accelerate Remediation with Actionable Guidance

Every validated finding includes proof-based evidence, detailed technical insights, and AI-powered remediation guidance. Developers receive clear, technology-specific recommendations that simplify vulnerability remediation and shorten the time required to secure applications.

Step 6: Continuously Revalidate Your Security Posture

Security is an ongoing process, not a one-time activity. ZeroThreat continuously rescans applications, verifies implemented fixes, and detects newly introduced vulnerabilities as applications evolve. This continuous testing approach helps organizations reduce the likelihood of future data breaches and maintain stronger long-term security.

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In Conclusion

Data breaches are not isolated incidents. They are often the result of preventable security gaps, human error, or unaddressed vulnerabilities. Understanding how breaches occur is the first step toward protecting sensitive information and reducing the risk of unauthorized access.

A strong security strategy combines preventive controls with continuous monitoring and regular security testing. Practices such as timely patching, multi-factor authentication, employee awareness, vulnerability assessments, and penetration testing help organizations detect risks before they become costly security incidents.

With ZeroThreat’s AI-driven penetration testing tool, you can identify known and hard-to-detect vulnerabilities with ease. It can discover complex vulnerabilities, security misconfigurations, known CVEs, and emerging vulnerabilities, ensuring there are no loose ends for a breach.