10 common types of data breaches and tips on how to prevent them

A data breach occurs when sensitive information is accessed or exposed without authorization, whether due to a malicious attack or accidental disclosure. A serious data breach could ruin your business’s reputation, let alone cost a fortune to recover from. Knowing the common ways that cybercriminals breach data security will help you keep your company’s defenses resilient to attacks.

What is a data breach?

During the third quarter of 2024 alone, data breaches exposed more than 422 million data records worldwide, while the data breach costs in 2024 reached a global average of USD 4.88 million.

You might think a data breach always has some malicious intent behind it. However, it can sometimes happen due to an accidental data leak or human error.

The most common types of data breaches

A data breach may easily become your company’s most expensive problem. Check out our comprehensive list of the different types of data breaches and their causes so that you can direct your security efforts toward preventing these threats.

1. Malware-type attacks

• What is it: Malicious software (malware), a form of malicious code, designed to infiltrate and damage computer systems, steal data, or disrupt business operations.
• How it works: Malware attacks systems through malicious downloads, email attachments, or software vulnerabilities. Once inside, it can perform various harmful actions, such as encrypting files for a ransom (ransomware), secretly gathering data (spyware), or spreading to other computers (worms).
• Business impact: Data theft, significant financial losses from ransom payments, operational downtime, and data corruption.
• Examples: The 2017 WannaCry ransomware attack infected hundreds of thousands of computers worldwide by exploiting a Windows vulnerability, causing massive disruptions for businesses and public services.

2. Social engineering and phishing attacks

• What is it: The psychological manipulation of individuals to trick them into divulging confidential information or performing actions that compromise security. These are common social engineering attacks.
• How it works: Attackers use deceptive emails, messages, or websites (phishing attacks) that appear to be from a trusted source. This social engineering aims to lure victims into revealing login credentials, clicking on malicious links, or transferring funds. Common forms include personalized spear phishing and whaling attacks that target high-profile executives.
• Business impact: Compromised credentials, malware installation, financial fraud, and unauthorized access to sensitive accounts and data.
• Examples: The 2016 breach of the Democratic National Committee (DNC) began with spear-phishing emails that tricked employees into revealing their passwords.

3. Attacks targeting passwords and authentication

• What is it: Any attack method focused on stealing, cracking, or bypassing user credentials to gain unauthorized access to systems or accounts.
• How it works: Attackers employ various techniques, including brute force attacks (systematically guessing passwords), credential stuffing (using stolen credentials from other breaches), and rainbow table attacks (using precomputed tables to crack password hashes). These attacks are especially effective against weak passwords.
• Business impact: Widespread account takeovers, unauthorized data access, identity theft, and loss of control over corporate resources.
• Examples: The 2021 Colonial Pipeline attack was initiated through a single compromised password for a VPN account that lacked multi-factor authentication, leading to a major fuel supply disruption in the U.S.

4. Unpatched software and outdated systems

• What is it: An attack that exploits known security flaws (vulnerabilities) in software, applications, or operating systems that have not been updated with the latest security patches.
• How it works: Cybercriminals scan for systems running outdated software and use publicly known exploits to gain unauthorized access, deploy malware, or steal data. Attacks often exploit known, patched vulnerabilities that organizations failed to update. Separately, zero-day exploits target previously unknown flaws before any fix exists.
• Business impact: Complete system compromise, ransomware infection, data theft, and loss of control over critical infrastructure.
• Examples: The massive 2017 Equifax data breach, which exposed the financial data and personal information of 147 million people, was caused by the company’s failure to patch a known vulnerability in the Apache Struts web framework.

5. Insider threats and internal data misuse

• What is it: A security risk originating from individuals within an organization, such as employees, former employees, or contractors, who have authorized access to data. These are known as insider threats.
• How it works: Insider threats can be malicious (an employee intentionally steals or leaks data) or unintentional (an employee accidentally exposes sensitive information through carelessness or human error).
• Business impact: Theft of intellectual property, exposure of confidential customer or enterprise data, financial loss, and damage to the company’s reputation.
• Examples: In 2018, a Tesla employee made unauthorized changes to the company's manufacturing operating system and exfiltrated large amounts of sensitive data to unknown third parties.

6. Third-party vendor breaches (Supply chain attacks)

• What is it: A breach where attackers compromise an organization by targeting its less-secure external partners, suppliers, or third-party vendors who have access to its systems or data, also known as supply chain attacks.
• How it works: By infiltrating a trusted vendor, attackers can introduce malicious code into software updates or use the vendor's legitimate access to pivot into the target organization’s network.
• Business impact: Unauthorized access to sensitive information, malware distribution through trusted channels, and widespread disruption affecting multiple organizations.
• Examples: The 2020 SolarWinds attack saw hackers compromise the company's software build process, distributing malicious updates to thousands of its high-profile customers, including U.S. government agencies.

7. Hacking

• What is it: The act of gaining unauthorized access to a computer system, network, or application by exploiting its vulnerabilities.
• How it works: Hackers use a variety of techniques to break through defenses. This includes SQL injection (injecting malicious code into a website's database), cross-site scripting (XSS, injecting malicious scripts into trusted websites), and exploiting buffer overflows to execute malicious code.
• Business impact: Unauthorized access, modification, or deletion of protected data; defacement of websites; and complete system takeover.
• Examples: The 2015 TalkTalk data breach in the UK resulted from an SQL injection attack that exposed the personal data of over 150,000 customers.

8. Network and session hijacking attacks

• What is it: Attacks that target active network connections and communication sessions to intercept, alter, or hijack data in transit.
• How it works: In a man-in-the-middle (MitM) attack, a criminal secretly intercepts communication between two parties. In session hijacking, an attacker steals a valid session token (e.g., a cookie) to take over a user's authenticated session and act as that user.
• Business impact: Interception of sensitive data like login credentials and financial information, unauthorized actions performed on behalf of the user, and redirection to malicious websites.
• Examples: The Firesheep Firefox extension, released in 2010, made it simple for non-technical users to perform session hijacking attacks on public Wi-Fi networks, highlighting the risks of unencrypted connections.

9. Misconfigured cloud storage and databases

• What is it: A data breach resulting from improperly secured cloud services or databases is a common form of access control breaches, leaving sensitive information exposed to the public internet.
• How it works: Administrators fail to implement proper security controls, such as requiring passwords or restricting public access, on cloud storage (like Amazon S3 buckets) or databases. This oversight makes the data discoverable and accessible to anyone.
• Business impact: Massive exposure of customer or corporate data, severe regulatory fines (under GDPR, CCPA, etc.), and significant reputational damage.
• Examples: A political data firm, Deep Root Analytics, left an Amazon S3 storage bucket publicly accessible, exposing personal information on ~198 million U.S. voters. As a result, 1.1 TB of data, including names, addresses, dates of birth, party affiliation, and modeled voter profiles was reachable on the open internet.

10. Physical and device-based threats

• What is it: Unauthorized access, theft, or misuse of data obtained through physical means rather than digital intrusion.
• How it works: This includes the physical theft of laptops, smartphones, or storage drives containing sensitive data. Other methods are "shoulder surfing" (watching someone enter a password), "tailgating" (following an authorized person into a secure area), and "dumpster diving" for discarded documents.
• Business impact: Loss of devices containing sensitive data, unauthorized access to secure facilities, and the potential for these physical breaches to enable further digital attacks.
• Examples: In a well-known 2008 incident, a laptop containing the unencrypted personal data of 600,000 UK Ministry of Defence recruits was stolen from a car.

Preventative measures and best practices

The onslaught of ways that attackers may breach your organization’s data security may seem overwhelming. However, a steady and proactive approach to security practices can strengthen your defenses against potential security breaches.

Network security

To take your corporate network security — and data protection — to the next level, you should implement a multi-layered approach that includes the use of firewalls, IDS, VPNs, and threat intelligence tools. Firewalls create a barrier between trusted internal networks and untrusted external networks, blocking unauthorized traffic and filtering malicious data. If someone manages to bypass the firewalls, an IDS (intrusion detection system) can detect unusual activity and provide real-time alerts, enabling your security teams to mitigate the threat promptly.

A VPN (virtual private network) secures data in transit, ensuring that remote workers and branch offices connect to the corporate network through encrypted channels to prevent eavesdropping and unauthorized access.

To top off your network security effort, start using a threat exposure management platform like NordStellar. It’s an advanced solution that automatically cross-references credentials found on the deep and dark web with your employee, customer, and partner accounts. If NordStellar’s data breach monitoring solution finds any leaked credentials, it notifies you instantly, giving you the chance to take action to secure your user accounts and resources.

Encryption

To protect sensitive corporate information, you should prioritize encryption by adopting data encryption in transit and at rest.

We advise encrypting your stored data on servers, databases, and devices to prevent potential security breaches, even if someone steals or compromises your data. You should also use encryption to secure data in transit between systems to prevent attackers from intercepting it during transmission over the internet or private networks.

Implement TLS protocols to secure web communications; use TLS 1.2 or higher. This will create encrypted connections between users and websites and protect sensitive information like login credentials and payment details from potential breaches.

Access controls

Curbing these types of security breaches also involves controlling who can access sensitive data and systems. Effective access management is crucial. Role-based access control is an effective approach that allows you to assign permissions based on an employee’s job responsibilities. It’s safest to only let individuals have access to the tools and data necessary for their role.

Equally important is the principle of least privilege, which means granting users the minimum level of access required to perform their tasks. By restricting permissions to only what’s essential, you can significantly reduce the attack surface, making it harder for cybercriminals to exploit compromised data.

Data minimization

It’s recommended to practice data minimization in any business. By collecting only the information necessary for your business operations, you avoid excess data — unnecessary or redundant information stored in your systems — that could become an attractive target for hackers.

A lean and secure data management system also includes regular purging of outdated or redundant data to reduce storage demands and limit the impact of potential security breaches.

Physical security

Ensure physical infrastructure is secure by securing server rooms with controlled access measures like keycards or biometric locks. Complement this with surveillance systems to monitor critical areas. A surveillance system may deter intrusions and provide evidence in case of security breaches.

Regular software updates

Protect your systems by regularly updating software, operating systems, and applications to patch vulnerabilities that attackers could exploit. Enable automatic updates where possible to ensure your systems always run the latest, most secure versions.

Strong password policies

Enforce strong password policies by requiring your employees to use complex, unique passwords to protect against identity theft and security breaches. Encourage your employees to use password managers to securely store and manage their credentials.

Implementing multi-factor authentication

Multi-factor authentication (MFA) adds an extra layer of security and protection against identity theft because users must verify their identity through multiple methods before they can gain data access to their accounts or company resources. MFA makes it harder for attackers to exploit compromised passwords alone.

Data backup and recovery plans

Make sure you regularly back up your data and have a set recovery plan if a data breach occurs. Storing your critical information securely is especially important to ensure data leak and data loss prevention in case of a cyber-attack, hardware failure, or system disruption.

Regular security audits

Conduct regular security audits to identify vulnerabilities, assess the effectiveness of your cybersecurity measures, and ensure compliance with industry standards. These audits will help you stay proactive in addressing potential threats before they become serious issues.

Employee training and awareness

The more your employees know about data breaches and security practices, the better equipped you are to both protect your business from security breaches and respond to them in a timely manner. Regular employee training is a must — especially in light of recent data security breaches that have shown how human error remains one of the biggest vulnerabilities.