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Updated: Feb 9, 2024   |   Stefan Jarlegren

How to detect data exfiltration: 5 steps

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Data exfiltration is the unauthorized transfer of data from an organization’s IT environment to an external location. Organizations must implement effective measures to detect data exfiltration and protect valuable or sensitive data.

In this post, we'll discuss the steps necessary to detect data exfiltration to secure your data resources.

In this article:

Wh‎at is data exfiltration?

Graphic illustration depicting file transfer/data exfiltration

Data exfiltration is also known as data exportation or data extrusion. The term exfiltration refers to activities performed by cybercriminals that put enterprise data resources at risk. It can also be used to describe insider threats, such as accidental data leaks by trusted employees or intentional data theft conducted by malicious insiders.

Me‎thods used in data exfiltration

‎One way that data exfiltration can be accomplished through physical access, such as physically removing storage media (such as a thumb drive) or IT components. While those threats are real and need to be addressed with physical security, this article focuses on how to detect data exfiltration by digital methods.

Exfiltration typically involves the unauthorized transmission, copying, or retrieval of sensitive information or valuable data from compromised systems. Threat actors may employ multiple methods in their attempts to exfiltrate data from an IT environment. 

The following are some of the more common data exfiltration techniques used by malicious entities.

  • Phishing and other types of social engineering attacks - Phishing and social engineering attacks are some of the most common data exfiltration methods. The purpose of the attack may be to steal credentials or plant malware that will later be used for exfiltration.
  • Compromised outbound emails - A compromised email account can be used by threat actors to transfer large volumes of data unobtrusively.
  • Advanced persistent threats (APTs) - APTs are long-term intrusions into an IT environment that enable threat actors to identify and possibly exfiltrate valuable data assets.
  • DNS tunneling - This technique uses encoded data in DNS communication to subvert security controls and enable data to be moved out of an environment without raising alarms.
  • Channel encryption - Threat actors may use encryption techniques to mask the true nature of transmitted data. This technique may be difficult to detect and allow data to be exfiltrated from the environment.
  • Vulnerability exploits - Cybercriminals may make use of newly discovered or unpatched vulnerabilities in IT hardware, software, or firmware to gain access to and exfiltrate company data.

Mi‎tre Exfiltration Techniques

In their ATT&CK framework, MITRE meticulously details a variety of exfiltration techniques, offering valuable insights into the methods used by adversaries to extract sensitive data from compromised systems. This framework categorizes exfiltration tactics based on factors such as the volume of data being transferred, the stealthiness of the transfer method, and the use of encryption or obfuscation to avoid detection.

MITRE highlights techniques like exfiltration over command and control channels, which allows attackers to stealthily move data while masquerading as normal network traffic. They also describe data compression methods to reduce the size and, consequently, the detectability of the extracted data. Additionally, MITRE addresses the use of automated exfiltration processes, where data is systematically gathered and sent to an external location without direct human command.

This breakdown of exfiltration techniques by MITRE not only aids cybersecurity professionals in understanding the myriad of ways data can be compromised but also guides them in developing more effective strategies to detect and mitigate these threats.

5 ‎essential steps to detect data exfiltration

Person using a laptop and smartphone to exfiltrate data

‎An organization must have the capability to detect attempts at data exfiltration to have any chance of preventing the loss of its valuable information. Detection requires a comprehensive plan that includes several steps. 

While there is no such thing as the perfect and impenetrable defense plan, these steps form a foundation and present a baseline against which data exfiltration attempts can be detected and prevented before they cause significant damage to the organization.

Inventory and classify all data resources

The first step to detecting data exfiltration is understanding where your valuable resources are stored so they can be effectively monitored and protected. Threat actors typically target high-value or sensitive data assets that can be leveraged for financial gain. 

In many cases, this is a small subset of your complete digital estate. Classifying data based on its business value and sensitivity allows an organization to deploy resources efficiently when implementing security measures. Modern solutions are able to detect and classify data as it is being used.

Develop an organizational data handling policy

Develop a data handling policy that specifies who in the organization can use data assets, as well as when and how they can be used. The policy should be built using the principle of least privilege, which only provides access to data resources to address business requirements. 

Any attempts to use data for non-job-related activities should be prohibited.

Implement robust authentication and authorization policies

Person using biometric fingerprint authorization as part of access control measures

‎Strong authentication and authorization policies should be implemented for robust access control. Operating with a zero-trust approach where users are continuously authenticated through the environment affords more effective protection. 

Multi-factor authentication should also be strongly considered to minimize the threat of stolen credentials being used to exfiltrate data.

Monitor all system and network activity

All system activity and network traffic needs to be monitored to effectively prevent exfiltration. By monitoring the organization's network, companies can identify suspicious activity—such as unauthorized access attempts—that could indicate the presence of external threats or malicious insiders. Multiple software solutions can be used to perform this monitoring including intrusion detection systems (IDS) and extended detection and response (XDR) platforms. 

Swift action should be taken by security personnel to remove intruders from the environment.

Employ a data loss prevention tool

A data loss prevention (DLP) tool automatically enforces an organization’s data handling policy, and acts as a data exfiltration prevention measure that restricts attempts at unauthorized data movement. 

It can generate alerts when policy violations occur, and ensure that restricted activities related to company data are not permitted. Reports will identify users making repeated attempts to access restored resources so they can be monitored and given additional data handling training.

De‎ploying a modern DLP solution

The Reveal Platform by Next is a modern data loss prevention platform that can detect and prevent attempts at data exfiltration. It automatically restricts users from violating the data handling policy which prevents them from exfiltrating data that they are unauthorized to transmit. 

The tool utilizes machine learning to effectively protect the data as it enters the environment. It also offers user training at the point of risk to help employees understand how they can use data resources securely.

Talk to our DLP experts and set up a demo to see how it can protect your business from data exfiltration.

Fr‎equently asked questions 

How does a phishing attack lead to data exfiltration?

Phishing attacks can lead to data exfiltration in several ways. Users may be tricked into providing login credentials that a threat actor can use to access and steal data. A victim may also be enticed into clicking on a malicious link that introduces malware into the environment to identify and exfiltrate valuable data.

Does a DLP solution prevent attempts at data exfiltration?

No, a DLP solution will not prevent users from attempting to exfiltrate unauthorized data resources. Individuals can still try to access data for which they are not authorized and attempt to send it offsite or to an external device. 

However, an effective DLP solution will prevent the activity from being carried out and alert security personnel that the attempt was made.

Why is it important to classify data resources?

It is important to classify data resources so they can be provided with a level of protection and resiliency that reflects their value. Sensitive personal data, intellectual property, and data that cannot easily be recreated may be designated as high-value data that requires additional protective measures or alternate backup schemes. 

Less valuable data can be protected using less sophisticated solutions.


See how Next protects your employees and prevents data loss