Few cybersecurity incidents have as much potential for harm as data exfiltration. Attacks where criminals seek to steal data from a business and then use it to extort money from the victim or sell it directly to others on the dark web, have grown hugely in popularity in recent years. In fact, according to our research, more than nine out of ten ransomware attacks (93 percent) now involve this tactic – and the consequences for this can be severe.

Extortion attempts that involve data exfiltration are also amongst the most costly types of cybercrime. For instance, a recent IBM report found that the average data breach costs firms $4.88 million in 2024 – a ten percent increase from 2023. However, for attacks that include extortion using exfiltrated data, this rises to $5.21 million.

However, the immediate financial costs don’t tell the whole story. Long-term consequences of losing sensitive data include reputational damage, loss of customer and investor trust, expenses such as class-action payouts or identity theft monitoring services for affected customers, and the exposure of future research and development plans to competitors.

To avoid these issues, it’s vital that firms have a clear strategy in place for detecting data exfiltration as early as possible and shutting it down before criminals have a chance to do damage. In this guide, find out why this matters and learn some of the essential techniques and technologies needed to prevent data exfiltration.

Early detection is critical in minimizing the damage caused by any cyberattack, and this is particularly true when it comes to combating data exfiltration. According to IBM, the average attack takes 291 days to detect and contain, while those that last over 200 days cost an average of $5.46 million.

This highlights the importance of quick detection. But in addition to increasing costs, the longer criminals are able to move unnoticed within a network, the more sensitive data they will be able to locate and exfiltrate.

In order to prevent this, there are several critical best practices that businesses should be following to keep a close eye on their entire systems and detect data exfiltration before criminals have a chance to remove information from the business.

Tools that can monitor all outgoing traffic in real-time and automatically raise any red flags are essential in stopping any data exfiltration in progress. The ability to quickly block any exfiltration without the need for human intervention greatly speeds up the process – however, businesses will have to make sure these tools are accurate and effectively configured to avoid any false positives that disrupt legitimate activities.

Understanding what normal network behavior looks like is a key first step in identifying any anomalies that require investigation. This is made much easier with the use of artificial intelligence and machine learning solutions that can build up a more complete picture of a company’s activities over time and spot anything unusual. Indeed, IBM found that firms deploying AI and automation tools can reduce breach costs by an average of $2.2 million.

Keeping a close eye on user behavior for any suspicious activity is also vital. In particular, administrators should be on the lookout for any frequent attempts to access sensitive data, particularly from accounts with high levels of privilege. Hackers will often look to compromise these in order to gain free rein inside a business, so a frequent review of these to make sure any inactive accounts are removed and that activity is within the scope of people’s responsibilities is a must.

It will be impossible to achieve the above best practices without access to the right technology. Cybersecurity requires a layered approach, as sophisticated attackers are always looking for new ways to bypass first lines of defenses such as firewalls and email security tools.

Therefore, a defense-in-depth strategy should include all of the following tools in order to provide full protection across the entire network.

• Security information and event management (SIEM) – These tools offer a centralized solution for monitoring systems and identify threats in real-time, using tools that gather data from across the entire business 
• Endpoint detection and response tools (EDR) – EDR software monitors activities across a firm’s endpoints, including PCs, laptops, servers and mobile devices looking for telltale signatures of attack
• Cloud security solutions – An increasing amount of business data is now held in off-site cloud computing solutions, and the Cloud Security Alliance rates data exfiltration as one of the key threats when using these storage options, so tools that are specifically designed to work in these environments are a must. 
• Anti Data Exfiltration software (ADX) – ADX goes beyond traditional EDR by adding behavioral analysis tools that can identify attempted infiltrations to ransomware command and control servers, destinations in high-risk locations or connections to the dark web.

Preventing data exfiltration is a challenge for many businesses. There are several reasons for this, with one of the most common issues simply being the size of today’s networks and the number of endpoints they contain. For instance, one estimate by the Ponemon Institute suggested that in 2022, the average large enterprise had 135,000 endpoints, all of which will need protection and monitoring to detect data exfiltration.

This has grown significantly in recent years, in part due to increased data sprawl and trends such as remote working. What’s more, many IT administrators may not even be aware of all their network connections due to the use of personal devices, consumer cloud storage solutions and other unapproved ‘shadow IT’ elements. This can make real-time monitoring of the entire network impossible.

Other issues include the fact that attackers are constantly evolving their activities to bypass defenses and evade detection. Therefore, traditional methods of spotting intrusions such as signature matching are often unable to identify the most advanced attacks, such as zero-day vulnerabilities or fileless malware.

Even if cybercriminals have successfully managed to enter and move within a network without detection, there will always be a few telltale signs to look out for that can indicate they are attempting to exfiltrate data. With the right tools, these can be spotted and reacted to quickly in order to shut down these efforts before any data actually ends up in the hands of hackers.

Common red flags to look out for include the following:

• Unusual data traffic patterns – Increases in traffic volumes or connections with unknown IP addresses can often indicate data exfiltration.
• Strange login activity – Look out for users accessing files or folders at unusual times – especially outside normal working hours, multiple failed login attempts or logins from users with administrator privileges.
• Unexpected network connections – Connections to external servers or unknown ports, or using non-standard protocols may be a sign of an attack in progress.
• Changes to file or folder permissions – Hackers may alter permissions or other configurations in preparation for an exfiltration attempt.
• Creation of new and privileged accounts – The addition of new accounts without authorization – especially ones with high levels of privilege – may help hackers gain a foothold within a network and improve their level of access to sensitive data.
• Unusual attempts to encrypt or compress files – Attackers may seek to apply their own encryption to files or employ data compression to make the exfiltration process quicker. 
• Disabled security tools – Many ransomware variants will try to disable standard security tools prior to exfiltrating data, so keep a close eye on these tools for any changes in their configuration.
• Abnormal user behavior – Unexpected user behavior may include out of hours working, suddenly increased levels of activity or accessing files that would be outside the individual’s normal job responsibilities, to name but a few.

While data exfiltration prevention tools are an essential last line of defense against today’s ransomware attacks, this should only be one part of a comprehensive strategy. In order to minimize the risk of falling victim to these attacks, it’s important to take a layered approach to cybersecurity.

As well as having the right technologies at every stage, from firewalls and multi-factor authentication to ADX, there are a few other elements that businesses must consider in order to protect themselves from such threats. These include:

• Employee training: This should take place on a regular basis to ensure all members of staff know what their responsibilities are and how to spot potential threats.
• Zero trust architecture: This approach takes the default position that all requests sent to the network are hostile until verified otherwise. It also incorporates principles of least privilege, to ensure user accounts do not have unnecessary access to data.
• Frequent patching: Vulnerabilities in outdated software are one of the easiest ways for hackers to gain access to a network, so it’s vital to ensure all systems and software are updated to the latest versions as soon as possible. Dedicated patch management software can help with this.

It’s important to remember that the job of securing businesses from data exfiltration should never be considered finished. With data exfiltration still proving highly profitable, hackers are always coming up with new methods of attacking firms, but with the right tools and software, companies can ensure their systems are future-proofed for whatever they might come up with next.