What Is Data Exfiltration? Definition and Prevention

By Indeed Editorial Team

Updated July 29, 2022 | Published July 21, 2021

Updated July 29, 2022

Published July 21, 2021

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Businesses, health care providers and government agencies are all common targets of data exfiltration. For such organizations, preventing exfiltration is important for protecting profits and sensitive data. If you're a network administrator or otherwise involved with your organization's cybersecurity, understanding data exfiltration can help you maintain network safety and prevent data loss.

In this article, we define data exfiltration, explain how it occurs and provide tips on how to prevent it.

Key takeaways:

  • Data exfiltration is an unauthorized data transfer, export, or copy taken from a secure computing device.

  • Both internal and external actors can perform data exfiltration, either intentionally or unintentionally

  • It’s important to educate employees and to enact data protection strategies to prevent data exfiltration efforts and other security compromises.

What is data exfiltration?

Data exfiltration, also known as data extrusion or exportation, is any unauthorized transfer, copying or exportation of data from a computing device. It’s a form of data theft that often involves a person manually accessing a computer or network or automating the process by uploading malware. Often, the targets of data exfiltration are:

  • Passwords and other login credentials

  • Bank account or payment card information

  • Personal identifying information, such as social security numbers and health records

  • Other sensitive data, such as protected files

Data exfiltration attempts often go unnoticed because they may resemble ordinary network activity, such as copying and uploading data to an external source or accessing accounts within a network. Activities such as these can cause a compromise of network security, loss of money and intellectual property and decreased consumer confidence.

Related: 15 Careers in Cybersecurity

How does data exfiltration occur?

Data exfiltration can occur externally or internally. External data exfiltration involves an entity from outside of an organization accessing its computer network, while internal exfiltration occurs when a member within an organization uses the organization's data in an unauthorized manner. Typically, there are three types of actors who can commit exfiltration:

  • Intentional outsiders: Intentional outsiders are non-members of an organization who attempt to access the organization's data, often remotely. Hackers are an example of intentional outsiders.

  • Intentional insiders: Intentional insiders are part of the organization whose data they attempt to exfiltrate. These are often former or current employees who wish to benefit themselves by exploiting or selling data.

  • Accidental insiders: These are members of an organization who have authorized access to data but accidentally compromise it through their actions. An example of an accidental insider is an employee who transfers data to a personal device intending to complete work outside the office.

Related: 28 Cybersecurity Tools You Can Use at Work (Plus Key Features)

Methods of exfiltration

There are also various methods by which data exfiltration occurs. Common methods include:

Social engineering

Social engineering is the practice of persuading others to perform desired actions or provide desired information. Often, this takes the form of fraudulent but seemingly legitimate communications.

For example, an intentional outsider pretending to be from the IT department might send emails to employees of a corporation, asking them to download a security application that's actually malware. With this malware, the outsider can access the network, collect sensitive data and extract the data from the network.

To prevent social engineering, a good practice is to ignore messages from unfamiliar accounts until you can verify their legitimacy. By refraining from opening such messages, you keep from initiating the procedure that can install malware on your device.

Related: 6 Penetration Testing Methods


Cracking is an effort to determine login credentials or locate concealed data through trial and error. It's a common technique among hackers to gain access to classified information.

When members of an organization use low-security passwords for their accounts, this leaves the accounts more susceptible to cracking. Thus, it's a good idea to use passwords that are harder to guess and to change passwords frequently.

Related: A Guide to Two-Factor Authentication

Physical data transfers

A form of internal exfiltration, physical data transfers are instances in which a member of an organization transfers sensitive data from the network to an external device.

For example, an employee of a retail corporation might access payment card information and copy this data onto a flash drive or their personal computing device. They can then use the data directly for their own benefit or sell it to others.

One way to prevent physical data transfers is to place restrictions on certain data so that only certain high-level members of the organization can see it. Any attempt of an unauthorized member to access this data can alert the network administrator, who can stop the access attempt.

Related: Learn About Being a Network Administrator

Transfers to unprotected devices

This is an accidental form of exfiltration that occurs when an employee of an organization copies sensitive data onto an external device that lacks security. Though the employee does not mean to compromise the data, it consequently becomes susceptible to exfiltration.

Because a copy of the data now exists on an unsecured device, hackers can more easily access it. Employees can prevent this practice by following their organization's network protocols and confirming that certain data is appropriate to copy before transferring it to an unprotected device.

Related: What To Do With a Network Administrator Degree

How to prevent data exfiltration

Here are some methods for preventing data exfiltration:

1. Educate employees

One of the most effective ways to prevent data exfiltration is to educate the members of an organization on best practices surrounding data use and threat prevention. By understanding how malicious actors use phishing and other methods to gain access to data, employees can better identify these methods when they arise and keep from allowing them to succeed.

Education should also involve setting a bring-your-own-device, or BYOD, policy, which allows employees to use their own computing devices for work activities. It's important to make clear to employees that they should not transfer sensitive data to their personal devices. Multi-factor authentication can also be a useful practice to show employees.

Read more: BYOD: What Does 'Bring Your Own Device' Mean?

2. Use detection software

Often, an organization is unaware that exfiltration has occurred until they experience the impact of having had its data exfiltrated. Thus, implementing software that can detect threats can keep exfiltrators from succeeding in their efforts. Data exfiltration detection software options often come equipped with features that can:

  • Identify suspicious users

  • Flag suspicious actions

  • Classify devices

  • Examine email activity

3. Classify your data

Classification is the practice of tagging pieces of data according to their characteristics and data type, such as sensitivity and importance. Classifying data allows an organization to place restrictions on use and implement policies that prevent exfiltration.

For example, restrictions on high-sensitivity data, such as personal identifying information, can limit authorized access to only certain users, and any attempt by an unauthorized user to access, move or duplicate the data can alert the network administrator.

Read more: A Guide to Data Classification (With Types and Examples)

4. Denylist suspicious sites

Denylisting, also known as blacklisting, is the practice of blocking access to domains associated with suspicious activity or potentially dangerous software. For example, if an employee does accidentally open a suspicious link, site blocking can prevent a successful connection with the site and thus keep the harmful content from infecting the endpoint and network.

Though excessive blocking can affect users' ability to complete work, moderate use of this method can prevent costly data exfiltration events.

Related: 12 Cybersecurity Certifications To Advance Your Career

5. Revoke permissions

The IT department can revoke the permissions of any member who no longer works for or with the organization. This includes former employees, former executives and third parties who've completed their service to the organization. Immediately removing these entities' access to your network can reduce the opportunities for leaked credentials and exfiltration events.

Related: An Overview of Role-Based Access Control: Benefits and Tips

6. Encrypt your data

Data encryption is among the most commonly used and secure methods by which organizations protect their information. Encryption transforms data into a code called ciphertext, which is unreadable unless you have a key or password to unlock it. This adds a layer of protection to your data by rendering it unusable.

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