Vulnerability Prioritization: What It Is and Why It Matters in Security
The digital world is a minefield. Every day, new vulnerabilities that malicious actors can exploit get discovered. In fact, more than 25,000 new common vulnerabilities and exposures (CVEs) were detected worldwide from January to August 2024.
With 261,900 CVEs already on the National Vulnerability Database (NVD), this rapid increase in vulnerabilities is a daunting challenge for cybersecurity leaders and their teams. Without proper prioritization, they cannot efficiently address even a proportion of these vulnerabilities.
This in-depth guide will help you understand the importance of vulnerability prioritization and implement a strategy that works for your organization.
PART 1
What Is Vulnerability Prioritization?
Vulnerability prioritization is the strategic process of evaluating and ranking vulnerabilities according to their potential impact and likelihood of exploitation. This process enables organizations to allocate their cybersecurity resources efficiently, focusing on the most critical threats to their security first.
Vulnerability prioritization is a key component of external attack surface management (EASM), following the initial step of uncovering an organization’s external attack surface.
What Are the Different Vulnerability Prioritization Methods?
Vulnerability prioritization is one of the foundations of a robust and effective cybersecurity program. In fact, agencies like the National Infrastructure Advisory Council (NIAC) and the Cybersecurity Infrastructure Security Agency (CISA) have developed valuable frameworks and guidelines to assist organizations with this process.
Below are some of the most commonly employed vulnerability prioritization methods.
Common Vulnerability Scoring System
The Common Vulnerability Scoring System (CVSS) is a standardized framework organizations use to assess the severity and impact of cybersecurity vulnerabilities. It provides a numerical score between 1 and 10 that helps organizations evaluate the severity of a vulnerability. The security issues can then be categorized into “low,” “medium,” “high,” or “critical.”
CISA Known Exploited Vulnerabilities Catalog
CISA’s Known Exploited Vulnerabilities (KEV) Catalog is an authoritative source of vulnerabilities that threat actors are actively exploiting. Organizations are strongly encouraged to incorporate the CISA KEV Catalog into their vulnerability management and attack surface management (ASM) frameworks to enhance vulnerability management and prioritize remediation efforts.
Exploit Prediction Scoring System
The Exploit Prediction Scoring System (EPSS) is a vulnerability scoring system that predicts the likelihood of a vulnerability getting exploited in the wild. The higher the score, the greater the probability that a security issue will get exploited.
EPSS generates a score between 0 and 1, representing the probability that the vulnerability will get exploited within the next 30 days.
Contextualized Approach
While CISA KEV, CVSS, EPSS, and other frameworks offer valuable guidance, they may not fully capture the unique risks and priorities individual organizations face when used independently.
As such, most organizations take into account their unique business context and employ a combination of the prioritization methods mentioned earlier. They also typically incorporate business-specific factors, such as asset criticality, risk appetite, regulatory compliance, and potential business impact, to effectively tailor the prioritization process to their specific needs.
What Factors Affect Vulnerability Prioritization?
We’ll talk about these factors in greater detail below.
Severity and Exploitability
Severity and exploitability are among the primary factors influencing how vulnerabilities are ranked. These factors can be measured using CVSS and CISA KEV status.
Severity refers to the potential damage a vulnerability can cause, such as data loss, financial loss, or operational disruption. A high-severity vulnerability can have significant consequences for an organization, including reputational damage, legal issues, and financial penalties.
Exploitability is the likelihood and ease with which an attacker can exploit the vulnerability. Attackers can use a highly exploitable vulnerability with minimal technical skills or resources. This factor can be influenced by the availability of exploits, the complexity of the attack, and the required user interaction.
Criticality of the Affected Assets
An asset’s criticality varies from one organization to another and depends on factors like:
- The asset’s role in core business functions
- The type and sensitivity of data handled by the asset
- Its relevance to regulatory requirements
- The potential damage breaching the asset can wreak on the organization’s reputation
A vulnerability may be ranked higher than other security issues if it affects critical assets. For example, security teams may prioritize a vulnerability affecting the domain hosting the organization’s software-as-a-service (SaaS) products.
That said, security teams must know which assets are affected by a certain security issue to assess the criticality of that vulnerability.
Figure 4: List of a vulnerability’s affected assets.
Risk Appetite
Risk appetite reflects the level of risk an organization is willing to accept. In the context of cybersecurity, this appetite dictates how organizations implement risk-based vulnerability management.
Some organizations may be more risk-averse and decide to eliminate a broader spectrum of vulnerabilities. They may invest heavily in security solutions to minimize their threat exposure. Meanwhile, organizations with a higher risk appetite, lower security budgets, or very complex infrastructure may be more willing to accept certain risks and focus on mitigating the most critical ones instead. Either way, they need to prioritize vulnerabilities accurately.
Patch Availability
The availability of a patch or workaround to address a vulnerability may impact its urgency. For instance, a vulnerability with medium severity but no available patch may require more attention and work hours to fix than a high-severity vulnerability with a readily available patch. This situation, especially if known to attackers, occurs because the lack of a patch increases the risk of exploitation, and the organization may need to implement temporary mitigation measures or workarounds until a patch becomes available.
Attack Surface Visibility
Since vulnerability prioritization comes after attack surface discovery in the EASM process, organizations ideally have a comprehensive and accurate inventory of their assets and vulnerabilities by the time they are ready to rank vulnerabilities.
Therefore, an organization’s understanding of its external-facing assets and their vulnerabilities directly affects its ability to implement vulnerability prioritization. After all, security teams cannot effectively evaluate and rank undetected vulnerabilities or scan unseen assets.
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PART 2
How Does Vulnerability Prioritization Work?
CISA is working toward automating vulnerability management, including prioritization, to reduce threat actors’ attack windows.
That said, here are the critical steps in vulnerability prioritization that can be followed both manually by security teams and automatically by EASM platforms and other security solutions.
Step #1: Vulnerability Assessment
This exercise aims to evaluate the detected vulnerabilities’ severity and relevance to the organization. The key questions to ask at this stage are:
- What assets are directly or indirectly affected by the security issue?
- Are any of the affected assets critical to business operations?
- Is the vulnerability being exploited in your industry? If so, attackers will also likely exploit it in your environment.
- What are the potential consequences of a successful exploitation (e.g., data loss, financial loss, and business disruption)?
Step #2: Risk Analysis
After evaluating the vulnerabilities, the next step is to quantify each vulnerability’s risks. This stage is where EPSS, CVSS, and other vulnerability scoring methods come into play. These frameworks provide numerical scores that help evaluate the severity and impact of vulnerabilities.
However, it’s important to remember that these scores are just one piece of the puzzle. Organizations must consider additional factors (e.g., risk appetite, patch availability, and others previously mentioned) beyond numerical scores to gain a comprehensive understanding of the risks posed by vulnerabilities.
Additionally, organizations must also consider qualitative factors. The experience and judgment of security professionals can provide valuable insights into risks that quantitative metrics may not fully capture.
Step #3: Rank the Vulnerabilities
At this stage, security teams use the insights gained from vulnerability assessment and risk analysis to effectively prioritize vulnerabilities.
For example, vulnerabilities with high EPSS and CVSS scores and are found in the CISA KEV Catalog are likely to pose significant risks.
On the other hand, vulnerabilities with a high CVSS rating and low EPSS score that are not found on the CISA KEV Catalog (such as CVE-2021-3618 in the screenshot below) may not be considered as high-risk as the previous example.
PART 3
How Do Various Industries Use Vulnerability Prioritization?
Effective vulnerability prioritization can benefit organizations across all sectors, notably as part of their EASM strategy. Here are some specific ways prioritization addresses industry-specific challenges.
Government Agencies
Vulnerability prioritization is crucial for government agencies to protect critical infrastructure and aid in complying with standards like the National Institute of Standards and Technology (NIST) Cybersecurity Framework. Government agencies can maintain cyber resilience and continuity of essential services by addressing vulnerabilities that can impact power grids, transportation systems, communication networks, and other critical systems.
Additionally, vulnerability prioritization is essential for national security. Government agencies must prioritize vulnerabilities actively exploited by advanced threat actors, including nation-states and organized crime groups, to protect sensitive information and national interests from cyber attacks.
Financial Organizations
Financial institutions handle a vast amount of personal information and financial records, making them prime targets for cyber attacks. Specifically, vulnerability prioritization helps them:
- Safeguard sensitive customer data
- Comply with industry-specific compliance frameworks like the Payment Card Industry Data Security Standard (PCI DSS)
- Prevent significant financial losses stemming from data breaches, operational disruptions, and noncompliance
Online Marketplaces
Online marketplaces collect and store a wealth of customer data, making them prime targets for cyber attacks. Vulnerability prioritization helps address security issues that can compromise customer data, enabling online marketplaces to safeguard their customers’ privacy and maintain their reputation.
Additionally, vulnerability prioritization helps maintain the uninterrupted operation of online marketplaces, which is essential for customer satisfaction and revenue generation.
IT and Software Companies
Ranking security issues and addressing the most critical ones first allow tech companies to:
- Protect their products from vulnerabilities introduced by third-party components
- Reduce the risk of data breaches
- Improve digital trust or the customers’ confidence in the security, privacy, and reliability of digital interactions and transactions
- Gain a competitive advantage over competitors with less robust cybersecurity practices
Healthcare Organizations
Healthcare organizations handle vast volumes of sensitive patient data, including medical records, financial information, and personal details. Vulnerability prioritization helps identify and address vulnerabilities that can expose this data to unauthorized access, resulting in data breaches and identity theft.
The process also enables them to comply with the Health Insurance Portability and Accountability Act (HIPAA) and avoid violations and potential fines.
It’s also important to note that vulnerabilities in healthcare systems can disrupt operations and lead to patient safety risks. By prioritizing vulnerabilities that can impact critical systems, healthcare organizations can prevent disruptions and ensure uninterrupted delivery of care.
PART 4
How Can Attaxion Help with Vulnerability Prioritization?
Attaxion is an EASM platform designed to assist organizations in proactively identifying and mitigating a wide range of vulnerabilities. Since the platform is built around industry- and government-initiated security standards, users can automatically see each vulnerability’s CVSS and EPSS ratings and CISA KEV status for immediate vulnerability prioritization and remediation.
Ready to see Attaxion in action? Schedule a customized demo now.
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PART 5
Frequently Asked Questions
How Can I Measure the Effectiveness of My Vulnerability Prioritization Process?
Track key attack surface metrics to measure the effectiveness of your vulnerability prioritization method. These metrics include the number of exploitable issues over time, the number of affected assets, and the distribution of vulnerabilities by severity.
What Is the CVE System?
CVE is a standardized naming system used to identify and catalog publicly known security vulnerabilities. Each CVE entry includes a unique identifier (e.g., CVE-2023-1234); a description of the vulnerability; and information about its severity, affected products, and potential exploits.
Why Is Vulnerability Prioritization Important?
As part of the EASM process, vulnerability prioritization helps security teams focus on the most critical threats first. In effect, it helps organizations reduce risks, comply with regulations, and ensure business continuity.
What Are the Challenges in Vulnerability Prioritization?
Some of the most common obstacles to effective vulnerability prioritization are budget constraints, staff shortages, lack of expertise, changing threat landscapes, and the complexity of modern IT environments.
How Can I Choose the Right Vulnerability Prioritization Method?
Selecting the most appropriate vulnerability prioritization method for your organization depends on several important factors, such as your organization’s size and the complexity of your IT environment.
Your industry and regulatory requirements may also influence your choice. Healthcare organizations may choose a method that allows them to protect essential healthcare services, while financial institutions may focus on protecting sensitive financial information. Some sectors may also be mandated by compliance standards like the NIST Cybersecurity Framework or International Organization for Standardization (ISO) 27001, which indicate their vulnerability prioritization method.
How Often Should I Reevaluate My Vulnerability Prioritization?
Reevaluating your vulnerability prioritization must be done regularly to maintain a strong cybersecurity posture. Some factors that trigger the need for reassessment are:
- Discovery of new vulnerabilities
- Changes to your organization’s risk profile changes
- Security incidents within the organization or industry
- New regulatory requirements