If battling ransomware isn’t challenging enough, these attacks have undergone a significant metamorphosis, with attackers shedding their encryption-based model for one of pure exfiltration. The result? A more stealthy, discreet approach that successfully bypasses traditional defenses to snatch sensitive data and employ a double or triple extortion scheme.

With pure exfiltration, businesses don’t realize they’re a victim until it’s too late. 

Fueling this Shift

Pure exfiltration’s ability to blend into its victims’ day-to-day workflow is fueling this adoption. It helps that businesses are handling enormous volumes of data moving in and out of cloud services, SaaS platforms, remote access tools, and third-party integrations. Monitoring the movement of legitimate activity is one thing. Asking teams to distinguish malicious activities from this sea of legitimate workflows is a task that most are not equipped to handle.

Attackers are also drawn to the fact that, unlike encryption, pure exfiltration doesn’t trigger a rapid response from its victims, giving them a chance to act before a ransom can be delivered. Quite the opposite. Since no systems go offline and no files are rendered unusable, pure exfiltration attacks can linger for weeks or months. 

Having the resource of time, attackers can patiently assess progress and even alter their approach as they go. For victims, it’s business as usual until the perpetrators send the extortion message. By that time, attackers have everything they need, while businesses lack the evidence to determine what went wrong and prevent future incidents. 

Pure Exfiltration and Traditional Defenses

Exfiltration comes in many forms. Some examples include:

• Exfiltration of Web services: Uploads stolen data to cloud storage services
• Exfiltration over alternative protocol: Uses DNS tunnels or other non-standard protocols to evade detection
• Exfiltration over physical medium: Copies sensitive data to USB drives or similar devices

Whatever the case, it should come as no surprise that pure exfiltration approaches are exposing a major gap in traditional ransomware defenses, which rely heavily on known malware patterns and detect malicious execution, encryption behavior, or lateral movement. 

Since pure exfiltration relies more on legitimate credentials, trusted applications, and approved cloud services, all activity appears legitimate. The challenge is exacerbated in environments where identity sprawl is common, such as SaaS heavy environments with many users, apps, and directories. Armed with legitimate credentials, attackers can gain access, query databases, export files, and synchronize content using the same tools employees rely on every day. This is why monitoring outbound traffic is insufficient when exfiltration volumes are small, incremental, and indistinguishable from routine operations.

The Costs of Pure Exfiltration

When it comes to the consequences of these attacks, the technical recovery is just the beginning. Since system restoration does not recuperate the leaked information or undo its exposure, businesses face regulatory violations that can result in audits, hefty fines, and a tarnished reputation. 

And then there are the extortion demands. While the attacker’s demands may be clear, the details about what data was taken are anything but. This grayness can impact the company’s response. For example, while one business may overreact and experience unnecessary disruption, another may underreact, exposing itself to further legal and compliance risks. Without knowing what’s been impacting it, it’s hard to know what the right course of action is.

What’s the Answer?

So how do you respond when the defining characteristic of the attack is its subtlety? It begins with understanding how data moves within your environment and who or what is authorized to access it at any given moment. That requires gaining tighter control over identities, clearer boundaries around data access, and being more scrutinous around unusual patterns, which, while not violating explicit rules, are subtly deviating from expected behavior.

Prevention is also key. Many exfiltration campaigns start with a common entry point. This could be phishing, credential abuse, or exploitation of an exposed service. Take steps to shrink the attackers’ ability to establish persistence or escalate access. Preventative approaches can neutralize ransomware payloads, block unauthorized access, preserve recovery tools, and disrupt exfiltration via cloud storage services, scripts, and command-and-control channels. As a result, this prevents attackers from gaining the leverage that is vital to their success.

Remember, the goal is not simply to alert teams of suspicious activity. It’s to constrain what an attacker can do even after gaining a foothold.

Exfiltration Is Not a Trend

Pure exfiltration attacks are not a passing trend. They are the latest evolution in attacker tactics that are exploiting modern enterprise environments where visibility is fragmented, and data flows are complex. And as organizations continue to adopt cloud services, remote work, and interconnected platforms, exfiltration and quiet data theft will only grow.

It’s important for companies to recognize that ransomware has not disappeared. It has become more selective and strategic. Organizations cannot afford to continue equating ransomware solely with locked files and other disruptions. Their success depends on embracing the idea that the absence of disruption does not mean the absence of compromise.