How EPSS Scores Improve Network Security Strategies

The Exploit Prediction Scoring System (EPSS) helps to predict the likelihood, or probability, that a software vulnerability will be exploited in the wild. It tells you which vulnerabilities are most likely to be targeted. 

Developed by a group of dedicated researchers, practitioners, and government personnel, EPSS scores vulnerabilities on a scale from 0 to 1. A score of 0.7, for example, means there's a 70% chance of exploitation.

How does EPSS work?

The idea of EPSS is to fill in the gaps left by other industry standards. While these standards measure the severity of vulnerabilities, they often don’t assess actual threats. 

EPSS uses current threat information from CVE, coupled with real-world exploit data, to provide a more accurate picture. Such data might come from sources like intrusion detection systems, honeypots, and malware analysis.

EPSS is publicly accessible. This means anyone can use the scores. But, importantly, while you don't need to join the EPSS SIG to use it, it's appreciated when users provide proper attribution. You can cite EPSS with a reference to its website or by acknowledging the creators in your work.

The EPSS model is regularly updated. This continual refinement ensures that EPSS remains reliable and relevant. 

EPSS is more than just a scoring system. It's a collaborative effort that brings together a wide array of experts. The model's development involved not just its creators, but also a data team and a special interest group (SIG) composed of over 200 members from various sectors around the world. 

This diverse team behind EPSS ensures its scores are as accurate and useful as possible. So, EPSS is a practical guide if you are part of a company network and looking to prioritize vulnerabilities for remediation. With its data-driven insights, you can focus on what matters, which is keeping your networks safer in an ever-evolving threat landscape.

Role and benefits of EPSS in securing company networks

By predicting the likelihood of a software vulnerability being exploited, EPSS allows you to prioritize which vulnerabilities need immediate attention. This is crucial because not all vulnerabilities pose the same level of threat. 

Helps you prioritize vulnerabilities more accurately

EPSS scores these vulnerabilities on a scale from 0 to 1, with a higher score indicating a higher probability of exploitation. This means you can focus your efforts on vulnerabilities that are more likely to be targeted, rather than spreading resources thin by addressing every single one.

The EPSS score isn't static; it evolves based on new data, giving you a dynamic and up-to-date view of the threat landscape. For example, during the Log4j vulnerability incident, EPSS provided scores that helped prioritize remediation efforts before the Common Vulnerability Scoring System (CVSS) scores were even assigned.

However, it’s crucial that you not use EPSS in isolation. It should be part of a wider risk management strategy. While EPSS provides an excellent measurement of exploit probability, it doesn't cover the entire risk spectrum. 

You still need to consider other factors like asset importance, exposure level, and the potential impact on your business processes. This comprehensive approach ensures that you are not just patching for the sake of it but prioritizing effectively.

Reduces your workload

By narrowing down the list of vulnerabilities that genuinely need attention, you can allocate resources more effectively. With CVSS providing the severity scores and EPSS adding a layer of exploit probability, you are better equipped to make data-driven decisions. 

The combination of EPSS and CVSS allows you to focus on vulnerabilities that are severe and likely to be exploited, making your patch management strategy both efficient and effective.

EPSS is the product of extensive collaboration among researchers, practitioners, and government bodies, drawing on a wealth of collective expertise. This collaborative nature guarantees that the EPSS model is continually improved and remains relevant in an ever-evolving threat landscape. 

Components of EPSS

The Exploit Prediction Scoring System (EPSS) is a complex tool, but it's built on some essential components. At its core, it harnesses the power of data to predict the likelihood of software vulnerability exploitation. 

Common Vulnerability Enumeration (CVE)

The CVE database is the EPSS’s primary source of vulnerability information. These CVE entries are like the building blocks of everything EPSS does, as they help identify and catalog vulnerabilities.

Now, what if a vulnerability in your system has an EPSS score of 0.8? That means an 80% likelihood of exploitation. How does EPSS figure that out? 

Telemetry data

It also draws from real-world exploit data. This includes telemetry data from diverse sources like intrusion detection systems, honeypots, and malware analysis. An example of telemetry data in action is during the Log4j vulnerability incident when EPSS scores helped companies figure out what to tackle first before any official CVSS scores were available.

Machine learning

Machine learning plays a significant role in making sense of all this incoming data. It's used to process and analyze the information, adapting as new data streams in. 

The EPSS model isn't static, and that's a good thing. It evolves based on new information. Continuous updates—as recently as March 7th, 2023—ensure that the EPSS model stays reliable and relevant for users.

A diverse range of expert contributors

Over 200 experts from various fields contribute to the system's development. This includes practitioners, researchers, and government personnel. 

This diverse expertise is crucial to refining and improving the model. It's why EPSS is robust and capable of providing high-confidence scores that help prioritize vulnerabilities in any company network.

EPSS isn’t meant to be used in isolation, though. Considering it alongside other factors like asset importance, exposure level, and business impact is crucial. 

This integrated approach is what makes EPSS an indispensable part of any security toolkit. Plus, it’s always being updated, drawing from multiple open and commercial datasets. So, if you hear of any potential data sources, the folks at EPSS would love to know!

Where else does the EPSS source its data?

The EPSS pulls in data from various sources to predict the likelihood of software vulnerabilities being exploited. One of the primary data sources EPSS taps into is the CVE database. That is the starting point or the foundational data on vulnerabilities.

EPSS doesn’t just stop there. It looks at the number of days a CVE has been published. This is crucial because a vulnerability that’s been around for a while might either have a known exploit or be dismissed if it’s not seen in the wild. 

EPSS also examines published exploit codes that can be found in platforms like Metasploit, ExploitDB, and GitHub. These platforms are known for housing detailed exploit information, which is vital for understanding how a vulnerability might be used maliciously.

Security scanners

Another layer of data comes from a variety of security scanners. These tools can provide insights into whether a vulnerability is being actively utilized by attackers. These scanners contribute to the EPSS model by feeding it real-time data, allowing EPSS to stay current with ongoing threats.

National Vulnerability Database (NVD)

The model also integrates data from the CVSS vectors, particularly from the base score available in the National Vulnerability Database (NVD). 

This adds an extra dimension by considering factors such as integrity impact and availability impact. The combination of CVSS severity and EPSS probability gives a more nuanced view of a vulnerability’s potential impact.

Common Platform Enumeration (CPE)

EPSS uses CPE data as published in the NVD. This helps identify the specific software affected by a CVE, allowing for more tailored risk assessments. By pulling all these data sources together, EPSS provides a robust framework for predicting which vulnerabilities could be exploited next, aiding in effective prioritization for remediation efforts.

EPSS algorithms and methodologies

EPSS leans heavily on machine learning to make sense of the vast amounts of data it collects. The approach starts with collecting extensive vulnerability information, which includes everything from CVE details to data from the CVSS. 

It's essential to know how this information is processed. This mostly happens in training the model. Here, the relationship between this vulnerability data and real-world exploitation is unearthed.

The EPSS model constantly evolves

Unlike static models, EPSS constantly evolves. The model isn't just set and left to run. It's continually optimized, measuring its own performance and tweaking its parameters to stay relevant. 

For example, when collecting data, EPSS looks at when information about vulnerabilities was published and when any exploits were attempted. This focus on timing is critical; it allows the model to connect the dots between different data points to refine its predictions. 

During the Log4j vulnerability incident, EPSS outperformed expectations by identifying threats before official CVSS scores were available. That's a testament to the dynamic nature of its algorithms. 

The EPSS model also considers the age of a vulnerability, whether it's been discussed on specific lists, and the presence of exploit code on platforms like GitHub. By leveraging such detailed inputs, the model makes well-informed predictions.

This is a clear example of the power of machine learning in cybersecurity. The model learns from historical data, like a student learning from past exam papers. It predicts which vulnerabilities might be exploited in the next 30 days. 

It's not just about collecting data; it's about understanding the patterns that emerge from this wealth of information. And when those patterns are understood, EPSS can offer valuable insights into which vulnerabilities need immediate attention.

This methodology isn't just a one-time process. EPSS constantly updates with new data, ensuring that its predictions remain accurate and timely. It's this continuous loop of learning and adaptation that makes EPSS a robust tool for companies looking to prioritize their security efforts effectively.

EPSS vs CVSS

EPSS is changing the way we think about software vulnerabilities. It's different from the Common Vulnerability Scoring System (CVSS), which many of us have relied on for years. 

Severity vs probability of exploitation

CVSS is great at measuring the severity of a vulnerability based on its inherent characteristics. It tells you how bad a vulnerability could be, but not necessarily how likely it is to be exploited. That's where EPSS steps in. It predicts the probability of a vulnerability being exploited in the wild, giving us an entirely new dimension to consider.

Think about the Log4j debacle. EPSS provided predictions before any official CVSS scores were even available, guiding us on which vulnerabilities required immediate attention. 

CVSS scores can be useful, but they are static. They don't change as more information becomes available. EPSS, on the other hand, updates regularly as new data comes in. It isn't just about the numbers; it's about real exploitation activity happening out there.

Complexity vs narrow focus

A criticism often labeled at CVSS is that it is too complicated or doesn't take into account organizational nuances or supply chain risks. 

Others argue that EPSS, while providing valuable insights, doesn't address the entire risk spectrum. It focuses solely on the likelihood of exploitation, and critics point out that this means it might not be as helpful for zero-day vulnerabilities or vulnerabilities that haven't been assigned a CVE ID yet.

EPSS and CVSS complement each other

Using these systems isn't an either/or decision. They complement each other. CVSS rates the technical severity, while EPSS sheds light on the exploitability aspect. 

Together, these two models offer a more rounded view of vulnerability management. It's about balancing those insights to prioritize your patching efforts effectively.

Those who lean into EPSS scores do so because it gives them the edge they need. Knowing which vulnerabilities are more likely to be exploited helps them concentrate resources where they matter most. But they also keep CVSS in mind for understanding the potential damage a vulnerability can cause. It's this blend of severity and probability that allows you to navigate the overwhelming world of cybersecurity threats with a bit more confidence.

Implementing EPSS in company networks

Integrate EPSS with your existing security tools

It is crucial to ensure that EPSS scores can be seamlessly utilized alongside other data sources like CVSS scores. This integration allows you to create a more comprehensive risk assessment framework.

For example, during the Log4j vulnerability incident, the EPSS scores proved invaluable. They helped security experts identify which vulnerabilities needed immediate attention even before any CVSS scores were available. It was a clear demonstration of the power and relevance of EPSS in real-world scenarios. 

Using EPSS in conjunction with CVSS allows you to prioritize effectively. While CVSS gives you an understanding of the severity of a vulnerability, EPSS provides insights into the likelihood of it being exploited. This combination empowers you to direct resources toward the vulnerabilities that pose the most significant threat.

In real-world terms, this means fewer sleepless nights worrying about impending cyber threats. Knowing which vulnerabilities are likely to be exploited helps you channel your efforts where they matter most. With limited resources, it is a huge relief to focus on critical vulnerabilities rather than trying to patch everything blindly.

Educate your team about its role in your security strategy. 

You should devote time to explaining how EPSS scores are derived, using real-world exploit data and insights from diverse sources like intrusion detection systems. 

This understanding is essential for everyone involved in your security operations, ensuring they appreciate why certain vulnerabilities were prioritized over others.

How Netmaker Helps Enhance Network Security

Netmaker can significantly enhance network security and management by providing a robust, secure way to connect machines across different locations. By setting up a virtual overlay network, organizations can ensure that their systems are interconnected securely, minimizing potential exposure to vulnerabilities. 

Netmaker's ability to create flat networks allows for seamless communication, facilitating efficient deployment of security updates and patches as prioritized by tools like EPSS. Features like Remote Access Gateways and Egress Gateways allow external clients to securely access internal network resources, ensuring that even remote or external machines are protected while accessing sensitive data.

Moreover, Netmaker's integration with WireGuard enhances security by ensuring encrypted communications between devices, reducing the risk of exploitation. With its user management capabilities, organizations can define roles and access levels, ensuring that only authorized personnel can make critical network changes. 

The use of ACLs (Access Control Lists) enables the control of peer-to-peer communications, allowing organizations to restrict unnecessary connections and focus on securing critical nodes. 

Sign up here to explore Netmaker and get started improving your network security and management.