Data theft: What is it, and how can you prevent it?

What is data theft?

Data theft occurs when cybercriminals illegally access and steal sensitive information from individuals or organizations. This information can include personal data like Social Security numbers and credit card details, login credentials for online accounts, or business information such as customer records and proprietary software code.

Attackers typically copy this stolen information to their own systems rather than simply deleting it from the original source. They then monetize the data by selling it on dark web marketplaces, using it to commit identity theft or financial fraud, or holding it for ransom. Data theft can happen through digital attacks like hacking and phishing or physical methods like stealing devices containing sensitive information.

What are the main issues that lead to data theft?

Data theft happens in many ways, often due to a mix of weak security practices, human mistakes, and technical vulnerabilities. Understanding the common causes can help you recognize potential risks and take steps to protect sensitive information.

Weak passwords

Weak passwords give attackers the easiest path into accounts. Simple passwords with personal information like names, birthdays, or common words take criminals just minutes to crack using automated tools. The problem gets worse when people reuse the same password across multiple sites. Once criminals crack it, they can access everything from social media to banking accounts. To help protect your data, it is important to create strong passwords that include a mix of uppercase and lowercase letters, numbers, and special characters.

Threats from inside a company

Insider threats usually come from people who have authorized access to a company’s network, such as employees, business partners, contractors, or freelancers. These insiders may intentionally or unintentionally leak or share sensitive information related to employees, the organization, or its customers.

Software vulnerabilities

Outdated software and poorly configured systems create security holes that hackers love to exploit. Criminals actively scan for systems running old versions of operating systems, applications, or security software because they know these often contain unpatched vulnerabilities. Even legitimate software can become a security risk if it’s not regularly updated with the latest security fixes.

Human error 

Humans make mistakes. An email sent to the wrong recipient, sensitive files attached to the wrong email, or critical files not secured with passwords may all lead to human error that causes data leaks. 

Physical theft

Physical theft remains a serious threat. A stolen laptop or phone can contain years of personal data, saved passwords, and sensitive documents. Paper documents are equally vulnerable because discarded bank statements, tax forms, or medical records can give criminals everything they need.

Infected downloads 

Free downloads, such as games, music, or movies, may sometimes contain malware or spyware. Cybercriminals use these infected files to steal sensitive data or take control of your device. Always be cautious when downloading free content from unknown sources.

What type of data is usually stolen?

Data thieves usually focus on two main areas: personal information and corporate data. Understanding what they target helps to better protect yourself and your business.

Information targeted in personal data theft:

• Personal details like name, address, phone number, and email address, which can be used for identity theft or impersonation
• Financial information such as credit card numbers and bank account details
• Login credentials (usernames and passwords) for social media, email, and banking accounts
• Health records, including medical history and insurance information
• Tax information like Social Security numbers and tax returns

Information targeted in corporate data theft:

• Intellectual property, such as business strategies and product designs
• Customer data, including payment details and purchase history
• Employee data like personal details, salaries, and Social Security numbers
• Confidential business information, such as contracts, financial reports, and internal communications
• Corporate tax data, including business tax filings and payroll information

Data theft examples 

The following data theft examples highlight the growing sophistication of cyberattacks and the challenges faced in protecting sensitive personal, financial, and medical data.

• Yahoo breach. In 2016, Yahoo announced that back in 2014 the company suffered  a large-scale data breach that affected over a billion users. According to Yahoo, an unauthorized party implemented malicious cookies that allowed them to access user accounts without the password. Threat actors targeted and stole users’ names, telephone numbers, email addresses, and security questions and answers.
• The Equifax case. In 2017, a data breach of this credit reporting firm exposed 147 million customers’ personal data, including names, Social Security numbers, birthdays, and addresses. Moreover, cybercriminals compromised the credit card data of around 209 thousand Equifax clients.
• Facebook’s data leak. In the data leak of 2019, millions of Facebook users’ personal records were found stored on public Amazon cloud servers. These records included account names and IDs.
• Uber data breach. In 2022, Uber suffered a data breach when a hacker accessed its network via stolen employee credentials. While the hacker compromised Uber’s systems and network, they did not steal any information because it appears that this was not the hacker’s intent. 
• X data breach. As recently as January 2025, large-scale data breaches have happened on X. A hacker called “ThinkingOne” shared the stolen data of over 200 million X/Twitter users. Released information included users’ personal details such as names, screen names, profile images, and email addresses. The information is believed to have come from a previous (and larger) breach where hackers stole over 2.8 billion user IDs and screen names.

How to prevent data theft

Protecting your data starts with simple, practical measures. Follow these steps to prevent data theft:

1. 1.Use strong, unique passwords. Create passwords with at least 12 characters, including uppercase letters, numbers, and symbols. Use a password manager to generate and store unique passwords for every account.
2. 2.Use multi-factor authentication (MFA). This tool adds an extra security layer by requiring an extra step beyond just your password, like a code sent to your phone or a fingerprint scan. Even if a criminal steals your password, they still can’t access your account without this second form of verification. 
3. 3.Be careful using public networks. They often lack security measures, and hackers use them as an entry point to devices. VPNs are a great solution whenever you need to connect to a public network securely. 
4. 4.Don’t overshare on social media. Every piece of information about you that ends up on the internet can be used for profiling, creating fake accounts, or serving you excessively targeted ads.
5. 5.Close accounts you don’t use. Accounts you create online require at least some personal information. To stay as private as possible online, delete all accounts you don’t use to reduce your digital footprint. 
6. 6.Use cybersecurity software. Keeping your data private is essential. Continuous monitoring systems like NordProtect can alert you to suspicious activity or breaches in real time, allowing you to respond to data theft quickly. 

How to respond when data theft incidents occur 

Data theft can occur to individuals and businesses. Follow these steps to respond to data theft for personal accounts:

1. 1.Change your passwords. Immediately update your passwords if possible. If your banking or other sensitive accounts are compromised, contact your institution and freeze them.
2. 2.Create a fact sheet. Write down everything you know about the incident, including what happened, who’s involved, and a timeline of events.
3. 3.Report the crime. If you’re a victim of fraud, file a report with the Internet Crime Complaint Center. For identity theft, report it to the Federal Trade Commission.
4. 4.Recover your data. Try to determine what happened to your personal data and get it back. Ask the recipient to delete or return it if sent by mistake. If a device is lost or stolen, retrace your steps or remotely wipe it. 

If your business faces data theft, follow these steps to respond effectively:

1. 1.Contain the breach immediately. Disconnect affected systems from your network and notify your IT security team or managed service provider right away. The faster you act, the less data criminals can steal and the smaller the potential damage to your business.
2. 2.Form a response team. Assemble a team that includes HR, management, security, and legal to review the breach and decide on the next steps. Track the process to prevent future incidents.
3. 3.Take affected devices offline. Disconnect any compromised systems immediately and monitor all suspected breach points. Make necessary repairs or apply security updates.
4. 4.Review your security. Work with your IT team to understand exactly how the breach happened and what data was compromised. Use this information to strengthen your defenses with updated software, better access controls, and additional employee security training.