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What is Data Exfiltration?

What is Data Exfiltration?

Harold Bell
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Data exfiltration is the unauthorized transferring of data out of a secure environment, usually for malicious purposes. It’s improper exporting of data; a data breach that ends up with data in the wrong hands. One might say it’s a fancy word for stealing. Outsiders, employees, and contractors can exfiltrate data, but it is often difficult to detect until it’s too late.

The process of data exfiltration involves sending privileged or sensitive information from a computer to an external destination without proper authorization. It can happen either manually, with physical access to a device, or automatically through malicious programming via networks. It’s an especially grave threat to organizations with a plethora of customer data, since data is the lifeblood of your organization, and in being the basis of innovation, provides you with a competitive advantage.

If a data exfiltration cyber-attack or malicious insider is successful, the results of data exfiltration could be catastrophic. In addition to the costs and distractions of remediating the breach, an exfiltration attack can lead to regulatory penalties, e.g., GDPR or CCPA fines. Legal liability is a risk, as is potential embarrassment and brand damage, such as when private email messages are publicized.

To ensure your critical information remains secure, data protection policies and practices need to take data exfiltration risks into consideration. By taking a proactive stance on system protection, you can help ensure all confidential data is safe from malicious actors. This article addresses the issue, discussing some standard techniques used to exfiltrate data and strategies organizations can use to prevent it.

How does data exfiltration occur?

Data exfiltration is frequently the goal of an attacker. In the MITRE ATT&CK framework, exfiltration is the penultimate stage in their multi-phase model of a cyber attack. It occurs after penetrating the target’s network, identifying data assets, evading detection, and moving laterally to the site where the data is stored. In the ATT&CK framework, only Command and Control (C2) comes after exfiltration. But considering data is often the ultimate goal of the attack, so command and control might not even be pursued.

This is either good news or bad news for cyber defenders. The good news is that cyber defenders have many chances to block an attacker before the exfiltration occurs. The bad news is that the attackers have a lot of chances to get to the data.

An external data exfiltration attack starts when a hacker infiltrates a corporate system to access confidential information, user passwords, or via APIs, as they are the path of least resistance to data. Hackers generally plant malicious software in end-user devices, such as computers or phones connected to the enterprise network.

Malware can then quickly spread through an organization’s systems and other devices, seeking out valuable corporate information to steal. It often remains hidden from the organization’s security measures until it has achieved its aims, either by gathering data in one fell swoop or accumulating bits of data over time without detection.

Corrupt insiders also pose a dangerous threat to organizations. They can quickly steal confidential data and move it out of the organization via email or cloud storage for their financial gain. Unintentional mistakes made by personnel can also cause security breaches. For example, an internal user could unknowingly leak data from the network by forwarding it to their personal email or saving it on unprotected cloud-based services and software platforms. While these actions may seem harmless, they inadvertently create vulnerabilities that are outside of the purview of the organization’s security team.

One of the biggest challenges in mitigating data exfiltration attacks is differentiating between normal and malicious data exports. If a user downloads a file, is that a cyber attack, or is it just someone doing his or her job? If encrypted data flows out of an organization’s network, is that a regular business transaction or an attack?

In the notorious Sony Pictures hack, an enormous amount of data left the company’s network in encrypted form over a period of months. No person or system noticed—revealing a huge problem in anti-exfiltration defenses. It’s not just Sony. Everyone has some version of this problem.

Types of data exfiltration

Data theft can occur through various means and strategies, such as over the internet or inside a company’s network. Cybercriminals have developed a variety of sophisticated techniques to steal data from businesses, including anonymizing connections; DNS tunneling; direct IP addresses; fileless attacks and remote code execution. These tactics allow criminals to remain undetected in their attempts to access sensitive information.

Cybercriminals employ a variety of data exfiltration tactics and malicious attack strategies, including:

  • Phishing attacks: Cybercriminals use phishing emails to trick individuals into giving up their login credentials, which the attacker can use to access sensitive data.
  • Outbound emails: Attackers can use outbound emails to send sensitive data to external email addresses outside the organization.
  • Downloads to insecure devices: Attackers can download sensitive data to insecure devices, such as personal laptops or USB drives, and then use that data for malicious purposes.
  • Uploads to external platforms: Attackers can also upload data to external platforms, such as cloud storage services, to exfiltrate it.
  • APIs: As confirmed above, APIs are the path of least resistance to data. Attackers can exfiltrate data by abusing APIs.

It is important to note that these are just a few of the many types of data exfiltration techniques that attackers use. As attackers become more sophisticated, they constantly develop new strategies to steal sensitive data.

How to prevent data exfiltration

Companies should be proactive in avoiding any attempts to steal data. To effectively safeguard an organization’s confidential data from cyber criminals, consider implementing a security system that incorporates features like:

  • Restricting access to unauthorized communication channels: Malware can exploit external communication channels as a means of exfiltration. Organizations must take measures to block any unauthorized communications, like compromised apps.
  • Safeguarding against credential theft and phishing attacks: In light of the abundance of phishing attacks, organizations must equip themselves with tools to deter users from entering credentials into imitation websites. These prevention tactics can also obstruct keystroke logging, which enables criminals to spy and record a user’s keyboard strokes, such as user IDs and password entries.
  • Empowering users: To successfully detect data exfiltration, organizations must train employees on the risks of cyberattacks. Staff should know the warning signs and avoid opening suspicious attachments and clicking links found in emails. These are basic yet critical steps to bolster digital security.

All that said, preventative data exfiltration measures mustn’t interfere with users’ activity. To ensure a good user experience, organizations should adopt tools that can accurately detect legitimate communication and application use, even in unfamiliar applications.


Data exfiltration is a growing and increasingly sophisticated security threat. Organizations must implement the proper precautions to guarantee that confidential information stays safe. Limiting access to unapproved sources is vital, as well as providing employees with the necessary knowledge to protect themselves from potential cyber risks. With an informed understanding of data exfiltration tactics and a robust strategy for prevention, organizations can confidently safeguard data and networks.

Harold Bell

Harold Bell was the Director of Content Marketing at Noname Security. He has over a decade of experience in the IT industry with leading organizations such as Cisco, Nutanix, and Rubrik, and has been featured as an executive ghostwriter in Forbes Technology Council and Hacker News.

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