Top 10 Most Common Causes of Data Breaches

Data breaches remain a major threat to enterprises in 2025. Despite advanced security tools, attacks are growing in number and impact.

According to IBM’s Cost of a Data Breach Report, the average cost of a data breach is now $4.62 million, and over 83% of companies have been hit more than once.

With remote and hybrid work becoming the norm, attack surfaces have grown. Meanwhile, hackers are using smarter tactics, like AI, phishing emails, and zero-day exploits, to break into systems.

But most breaches don’t happen because of complex attacks. Major data breaches are caused by avoidable mistakes, such as weak passwords, poor access control, or unpatched software.

Let’s look at the top 8 causes of data breaches in 2025—knowing these risks helps prevent data breach incidents, protect your data, stay compliant, and avoid costly damage.

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TL;DR

• Phishing and social engineering are common ways attackers trick employees into sharing sensitive data or clicking harmful links, often leading to a breach.
• Weak, reused, or stolen passwords continue to be a major vulnerability, especially when enterprises fail to implement strong password policies or multi-factor authentication.
• Outdated software and poorly set up cloud systems make it easy for hackers to break in—something that can be avoided with regular updates and proper settings.
• Insider threats and human mistakes, like sending emails to the wrong person or sharing passwords, still cause many data breaches.
• CloudEagle.ai helps prevent data breaches by automatically giving and removing access, setting role-based rules, and keeping an eye out for unusual activity. This gives companies better control and keeps all their SaaS apps safe.

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What is a Data Breach?

A data breach is a security incident where unauthorized individuals gain access to confidential or sensitive information. This could include customer data, financial records, trade secrets, or login credentials. These breaches can occur due to cyberattacks, human error, or system vulnerabilities.

When a data breach happens, it can lead to serious consequences, ranging from financial loss and legal penalties to loss of customer trust. Businesses of all sizes are targets, and with the rise in cloud adoption and remote work, the risk has grown even more complex.

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What Happens During a Data Breach?

A data breach usually begins when attackers exploit weak spots in a company’s systems, such as poor passwords, phishing emails, or unpatched software. Once they gain access, they can steal, lock, or destroy valuable data.

Many breaches remain hidden for weeks, giving hackers more time to do damage. Once discovered, companies must act fast to contain the threat, inform affected users, and fix the issue. The whole process can be expensive, stressful, and damaging to the business’s reputation.

Here’s a quick breakdown:

• Hackers break in using weak passwords, phishing, or unpatched software.
• Once inside, they may steal, lock, or delete sensitive data.
• Many breaches go unnoticed for weeks or even months.
• Companies must act fast to stop the attack and limit the damage.
• Affected users need to be informed, and systems must be secured.
• The breach often leads to big costs and hurts the company’s reputation.

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10 Most Common Causes of Data Breaches

There are multiple causes of data breaches, and major data breaches don’t happen by chance—they’re often the result of common, preventable issues.

Let’s explore the most frequent causes behind these incidents.

1. Phishing and Social Engineering

The number one cause of data breaches is phishing. Phishing is when attackers send deceptive messages, often by email, pretending to be a trusted source. These messages trick users into revealing passwords or clicking on malicious links. Modern phishing attacks are highly targeted and convincing, making them hard to detect.

Social engineering goes a step further by manipulating users through psychological tactics. For example, an attacker might pose as a coworker or vendor to gain trust and access sensitive systems. These tactics work because they target human behavior, not technical flaws.

For example, in 2020, Magellan Health fell victim to a sophisticated phishing attack where hackers tricked employees into sharing login credentials, exposing the data of over 1.7 million individuals.

2. Weak, Reused, or Stolen Credentials

Using weak or reused passwords is one of the easiest ways attackers can break into systems. If a user uses the same password across platforms and one of them gets breached, attackers can try those credentials on other sites—a technique known as credential stuffing.

Stolen credentials are often sold on the dark web, and without multi-factor authentication (MFA), attackers can use them to access sensitive accounts. Implementing stronger password policies and access controls is key to reducing this risk.

In 2023, several Washington Post journalists had their Microsoft 365 accounts compromised, reportedly due to reused or weak passwords, showing how vulnerable high-profile organizations can be without strong credential policies and multi-factor authentication.

3. Malware and Ransomware

Malware is malicious software designed to disrupt, damage, or gain access to systems. It can enter through infected email attachments, downloads, or even USB drives. Once inside, malware can spy on users, steal data, or open a backdoor for attackers.

Ransomware, a specific type of malware, encrypts your data and demands payment to restore access. These attacks can shut down entire operations and cause massive financial loss. Even after paying, there’s no guarantee of data recovery, making prevention and regular backups essential.

For instance, in February 2024, Change Healthcare, a major U.S. healthcare technology firm, was hit by a ransomware attack that encrypted sensitive data of nearly 100 million patients, causing major disruptions and financial losses.

4. Insider Threats

Insider threats come from people within the enterprise—employees, contractors, or partners—who misuse their access to systems. Some do this maliciously, while others cause harm unintentionally through negligence or carelessness.

Since these users already have authorized access, their actions often bypass traditional security defenses. This makes it critical to monitor user behavior, conduct regular access reviews, and limit access based on job roles (least privilege principle).

A real-world example is Tesla, where in 2023, two former employees leaked the personal information of more than 75,000 colleagues, illustrating how internal threats can cause significant damage even in tech-savvy companies.

5. Unpatched Software and Systems

When vendors release updates, they often include patches for known security vulnerabilities. If these aren’t applied in time, attackers can exploit the weakness to breach the system, just like the massive Equifax breach in 2017.

Many enterprises delay updates due to compatibility issues or resource constraints. However, skipping patches creates a wide-open door for hackers. A solid patch management process and automated updates help close these gaps quickly.

One of the most infamous examples is the Equifax breach in 2017, where hackers exploited an unpatched vulnerability in Apache Struts, leading to a data leak affecting 148 million Americans.

6. Misconfigured Systems and Cloud Storage

Misconfigurations, especially in cloud platforms like AWS or Azure, can expose sensitive data to the public. For example, many data breaches have occurred because storage buckets were set to “public” access without proper controls.

Even skilled IT teams can overlook complex settings, particularly as cloud environments scale. Continuous security audits and cloud security posture management tools can help detect and fix misconfigurations before attackers find them.

In 2022, Breastcancer.org accidentally exposed patient data through a misconfigured Amazon S3 bucket, demonstrating how cloud misconfigurations can publicly expose sensitive information without proper oversight.

7. Lack of Encryption

Encryption protects data by converting it into unreadable code unless accessed with the right key. Without it, anyone who gains access to the system can read and use the data, increasing the damage during a breach.

Encrypting data at rest (on storage devices) and in transit (when it's being sent) is a basic but essential layer of security. Even if an attacker breaches your network, encryption ensures the stolen data is useless without decryption keys.

8. Physical Theft or Loss of Devices

Lost or stolen laptops, USB drives, or phones can result in serious data breaches, especially if the devices contain sensitive files or credentials. Without encryption or password protection, a thief can access everything easily.

With more remote work, devices are now used in cafes, airports, and homes, making them easier to lose or steal. Device encryption, remote wiping, and endpoint security tools help protect against physical breaches.

In 2017, Lifespan Health System reported a breach after an unencrypted laptop was stolen from an employee’s car, exposing patient data and resulting in a $1.04 million settlement.

9. Third-Party Vendor Vulnerabilities

Many enterprises rely on vendors for IT services, software, or support. If a vendor has poor security practices, attackers can use them as a backdoor into your system—a tactic called a supply chain attack.

To mitigate this risk, enterprises must vet vendors, enforce security policies through contracts, and monitor third-party access. Tools like vendor risk management platforms help streamline and secure these partnerships.

In 2025, Marks & Spencer (M&S) experienced a cyberattack stemming from a compromised third-party vendor, causing system outages and reportedly leading to losses of over £300 million.

10. Human Error

Despite advanced security systems, human mistakes still cause major data breaches. Clicking on suspicious links, misconfiguring settings, or sending sensitive files to the wrong recipient are common errors with serious consequences.

“The weakest link in the security chain is the human element.” — Kevin Mitnick, former hacker and cybersecurity consultant

Regular employee training, simulated phishing tests, and clear security policies can reduce the chances of mistakes. Pairing human vigilance with automation also lowers risk by reducing reliance on manual decisions.

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Common Methods Used for Data Breaches

Hackers use several tried-and-tested methods to infiltrate systems and steal data. Here are the most common techniques they rely on.

Phishing Attacks: Phishing remains one of the most common and effective attack methods. Cybercriminals send emails that look legitimate, mimicking trusted brands, coworkers, or financial institutions. These messages often create a sense of urgency, tricking users into clicking malicious links or entering credentials into fake websites.

“Phishing is a major problem because there really is no patch for human stupidity.” — Mike Danseglio, Cybersecurity expert at Pluralsight

Exploiting Vulnerabilities: Hackers constantly scan the internet for systems running outdated software or misconfigured applications. When they find a vulnerability, such as an unpatched server or an open database, they exploit it to gain access and move data without authorization.

Malware and Ransomware: Malware is malicious software designed to damage or gain unauthorized access to systems. It can arrive via email, USB drives, or infected websites. Once deployed, ransomware can spread quickly across networks, halting business operations.

“Ransomware is more about manipulating vulnerabilities in human psychology than the adversary’s technological sophistication.” — James Scott, Senior Fellow at the Institute for Critical Infrastructure Technology

Credential Stuffing: Credential stuffing is when hackers use stolen usernames and passwords from one website to try logging into other accounts. Since many people reuse passwords, attackers often get in. They also use automated tools to try thousands of logins quickly.

Insider Threats: Insiders—like employees, contractors, or vendors—can unintentionally leak data or intentionally misuse their access for personal gain. These threats are hard to detect because insiders often have legitimate access.

“Insider threats are not viewed as seriously as external threats… but when companies had an insider threat, in general, they were much more costly than external incidents.” — Dr. Larry Ponemon, cybersecurity researcher 

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What are the Consequences of Data Breaches?

Data breaches can have serious consequences, from financial loss to reputational damage. Let’s look at some examples of privacy breaches to understand what’s at stake.

Financial Loss: Major Data Breaches can cost companies millions in fines, recovery efforts, and lost business. The impact often continues for months due to downtime and customer churn. For example, U.S. insurance firm CNA Financial paid $40 million in ransom after a ransomware attack shut down its network and disrupted operations for weeks.

Reputational Damage: Trust is a cornerstone of any business relationship. When a breach occurs, customer confidence often takes a hit. Negative media coverage and social backlash can lead to lost customers and investor doubts. For example, British Airways was fined £20 million after data from 400,000 customers was stolen, severely hurting its brand image.

Operational Disruption: Breaches often force enterprises to shut down systems, suspend operations, or restrict access during investigation and recovery, bringing productivity to a standstill. For example, the Colonial Pipeline attack caused a 6-day shutdown, leading to fuel shortages and showing how cyberattacks can disrupt critical services.

Legal and Compliance Issues: Depending on the region and industry, enterprises are bound by data protection laws like SOC 2 Type II, ISO 27001, GDPR, HIPAA, etc. A breach may result in legal action, regulatory investigations, and mandatory public disclosures. Non-compliance with these regulations can lead to steep penalties, audits, and court battles.

For example, H&M was fined €35 million by German regulators for violating GDPR. The company had improperly monitored employees' data, showing how mishandling information, even internally, can trigger major compliance fallout.

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How Can You Prevent the Causes of Data Breaches?

Preventing a data breach requires a mix of smart practices and strong technology. Here are some effective ways to protect your organization.

Implement Strong Access Controls

Limit app access based on roles. Only give employees the data and tools necessary to perform their job. Enforce multi-factor authentication (MFA) to protect logins—even if a password is stolen, the second factor adds a layer of security.

Review access privileges regularly. When employees change roles or leave the company, revoke or adjust permissions immediately to avoid unnecessary exposure.

Keep Software Updated

Cybercriminals exploit known software vulnerabilities. Enterprises that delay patches risk exposing themselves to preventable breaches. Set up automated update tools or patch management systems to ensure timely upgrades.

This includes not just your main software but also plugins, firmware, and third-party apps that might not be front of mind.

Train Employees Regularly

Your team is your first line of defense. Educate them on how to recognize phishing emails, avoid unsafe websites, and report suspicious activity. Make cybersecurity training part of onboarding and continue with regular refreshers.

Interactive exercises, simulated phishing campaigns, and real-world examples make training more engaging and effective.

Encrypt Sensitive Data

Use encryption to protect data at rest (stored) and in transit (moving between systems). If data is stolen but encrypted, it remains unreadable to attackers unless they also have the keys. Encryption is a foundational layer that reduces the severity of a breach, even if perimeter defenses fail.

Monitor and Audit Systems

Use intrusion detection systems (IDS) and security information and event management (SIEM) tools to track unusual behavior in real time. Regular audits of system logs can reveal attempted breaches, insider misuse, or failed login attempts. Early detection reduces damage and improves response time during incidents.

Work with Trusted Vendors

Third-party vendors are often the weakest link. Assess their security posture, review contracts for data handling terms, and monitor their compliance with security standards. Use vendor risk management platforms to continuously evaluate partners and reduce supply chain risks.

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What is a real-world examples of a data breach?

Let's look at some of the biggest cybersecurity breaches that took place in recent times. These incidents offer important lessons on what went wrong and how to avoid similar risks.

1. LinkedIn (2021): In a major incident, over 700 million LinkedIn user records were scraped and leaked on a hacker forum. Although the company stated the data was public information, the breach included phone numbers, emails, and geolocation data.

This event highlighted the risks of data scraping and raised serious privacy concerns, even if the data wasn’t technically "hacked" in the traditional sense.

2. Equifax (2017): A critical Apache Struts vulnerability led to the exposure of sensitive data from 147 million Americans. Hackers accessed names, birth dates, Social Security numbers, and credit histories.

Equifax faced massive public and governmental backlash. They ultimately settled for over $700 million, making it one of the most costly breaches in history.

3. Marriott International (2018): Hackers infiltrated Starwood’s guest reservation system (acquired by Marriott) and accessed data from 500 million guests, including passport numbers and credit card information.

What’s worse, the breach had begun in 2014 and went unnoticed for nearly four years, highlighting serious lapses in detection and acquisition due diligence.

4. Capital One (2019): A former AWS employee exploited a misconfigured firewall to access personal data from over 100 million Capital One customers. This included Social Security numbers and credit applications.

The breach led to regulatory scrutiny around cloud misconfigurations and emphasized the importance of cloud security best practices.

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How CloudEagle.ai Can Manage Access and Help You Prevent Data Breaches?

CloudEagle.ai is an advanced SaaS management and access governance platform that simplifies access visibility, automates provisioning and deprovisioning, and enforces least-privilege principles across your software stack.

Here’s how CloudEagle.ai helps your team to stay secure, reduce risk, and prevent costly breaches.

Automatic Access Provisioning and Deprovisioning

Managing user access manually is time-consuming and prone to error. CloudEagle.ai eliminates this risk by automating access provisioning when a user joins the company, switches teams, or leaves.

Provisioning: When a new employee starts, CloudEagle automatically gives them access to the tools they need—like Slack, Salesforce, or Zoom—based on their department and role.

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Deprovisioning: When someone resigns or moves to a different team, access to irrelevant apps is automatically revoked.

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Orphaned accounts (where former employees still have access) are a common entry point for attackers. Automating access updates ensures no one retains permissions they shouldn't have, reducing insider threats.

Role-Based Access Control (RBAC)

Instead of granting access on a case-by-case basis, CloudEagle lets you define roles (like “Marketing Analyst” or “HR Manager”) and assign specific access permissions to each role.

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For example, a marketing analyst gets access to Canva and HubSpot, while an HR manager gets access to BambooHR and DocuSign. Once roles are configured, you can onboard or reassign employees faster and more accurately.

This keeps access tightly controlled and organized. It also reduces the risk of users accessing sensitive data they don't need, helping enforce the principle of least privilege.

Just-in-Time (JIT) Access

Sometimes, employees or contractors need temporary access to a SaaS tool. With CloudEagle, you can grant time-bound access with automatic expiration. A contractor working on a one-month project needs access to Jira. You grant access for 30 days, after which it’s auto-revoked.

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This eliminates the risk of long-term access staying active after the project ends. It reduces the attack surface by limiting exposure to sensitive systems.

Automated Access Reviews

CloudEagle sends automated reminders to app owners and team leads to review who has access to what. They can quickly approve, deny, or update permissions through a simple dashboard.

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Every quarter, managers get a list of users with access to tools like Workday or Salesforce and can easily revoke access for users who no longer need it.

Without regular app access reviews, companies end up with outdated permissions, which attackers can exploit. Reviews keep your access lists clean and compliant.

Real-Time Anomaly Detection

CloudEagle monitors login behavior and user activity. If it spots something unusual, like a login from another country, multiple failed login attempts, or unusual data downloads, it alerts the security team.

An employee who normally logs in from India suddenly logs in from an unknown location at 2 a.m.—an alert is triggered. Catching anomalies early helps stop breaches before they cause damage. This proactive monitoring is key for fast incident response.

Access Logs and Audit Trails

Every action taken through CloudEagle—like granting access, revoking permissions, or modifying roles—is logged automatically. These logs are organized, searchable, and ready for export. During a compliance audit, you can pull up a log of who accessed Salesforce, when, and what actions they took.

Audit logs provide visibility and accountability. If a breach occurs, logs help you trace the root cause and demonstrate that your controls were in place.

Identity Provider (IdP) Integration

CloudEagle integrates with leading identity providers like Okta, Azure Active Directory, and Google Workspace to sync user identities and access policies in real time. When a user is removed from Google Workspace, CloudEagle reflects that change instantly and deactivates access to connected SaaS apps.

This prevents gaps or lag between identity systems and SaaS tools. It also ensures consistent, company-wide access policies.

Support for Compliance and Governance

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CloudEagle helps you stay compliant with data privacy laws and industry standards like SOC 2, GDPR, HIPAA, and ISO 27001 by:

• Enforcing strict access controls,
• Maintaining logs and audit trails,
• Helping demonstrate control over data access during audits.

Non-compliance can lead to regulatory fines, lawsuits, and loss of trust. CloudEagle simplifies compliance without heavy manual work.

Self-Service App Catalog

CloudEagle.ai simplifies access management with its intuitive self-service app catalog. Employees can view the applications they already have access to and request new ones directly through Slack.

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If a similar app is already available within the organization, the platform will guide users to utilize it, helping reduce app sprawl and unnecessary purchases.

Admins receive instant notifications via Slack and email when requests are submitted, allowing for faster approvals and better oversight.

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Conclusion

As organizations embrace more SaaS applications, the risk of data breaches rises, especially when access is poorly managed. From phishing to insider threats, attackers exploit any gap they can find. That’s why controlling who has access to what is more important than ever.

CloudEagle.ai simplifies access management through automation, role-based controls, anomaly detection, and audit-ready visibility. It helps businesses stay compliant, reduce the IT burden, and protect sensitive data—all without slowing down operations.

In short, if you're using multiple SaaS apps and want to prevent data breaches before they happen, CloudEagle.ai gives you the control, security, and peace of mind you need.

Schedule a demo with CloudEagle.ai and learn how you can create a secure environment in your organization and stay ahead of data breaches.

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Frequently Asked Questions

1. What causes 90% of data breaches?

About 90% of data breaches are caused by human error, like clicking phishing links, using weak passwords, or misconfiguring systems. Even with strong security, one employee mistake can lead to a serious breach.

2. What do most data breaches start with?

Most data breaches start with phishing—fake emails that trick users into clicking bad links or sharing passwords. These often look like messages from trusted sources. Once in, attackers can steal data or harm systems.

3. What are the 5 steps of a data breach?

A typical data breach unfolds in five main stages:

• Reconnaissance – Scouting the target.
• Access – Breaking in.
• Escalation – Gaining control.
• Exfiltration – Stealing data.
• Cover-up – Hiding the breach.

4. Which business has the highest breach count?

Tech and healthcare companies face the most breaches. Tech firms store massive user data, while healthcare providers hold sensitive medical info, often on outdated systems with weaker security.

5. How to handle a data breach?

Responding to a data breach involves several steps:

• Detecting and containing it quickly,
• Investigating the cause and the data impacted,
• Notifying affected users and authorities,
• Fixing vulnerabilities and strengthening security,
• Learning to prevent future issues.

6. What is the biggest cause of personal data breaches?

The biggest cause of personal data breaches is phishing. This happens when someone is tricked into clicking a fake link or sharing personal information, like passwords or bank details. Phishing is common because it targets people directly and can easily fool even careful users.

7. What is the cause of the majority of data breaches?

The majority of data breaches are caused by human error and phishing attacks. Most breaches start when someone accidentally clicks a malicious link, uses a weak or reused password, or mishandles sensitive data.

8. Who is most likely to cause a data breach?

Most data breaches happen because of people inside the company, like employees or contractors. They might click on a bad link, send data to the wrong person, or accidentally leave systems open. Some do it on purpose, but most of the time, it’s just a mistake.

9. What are the three kinds of data breaches?
There are three main types:

• Confidentiality breach: When someone sees data they shouldn’t.
• Integrity breach: When data is changed without permission.
• Availability breach: When people can’t access data because of things like ransomware.

10. What are the 5 steps of a data breach? 

If there’s a data breach, here’s what to do:

• Find out what happened.
• Stop the breach from spreading.
• Check what data was affected.
• Tell the people and authorities who need to know.
• Fix the problem so it doesn’t happen again.

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