CVSS stands for Common Vulnerability Scoring System. It is a standardized framework that provides a way to assess the severity of vulnerabilities in computer systems, networks, or software applications. The CVSS system uses a set of metrics to evaluate the characteristics and potential impact of a vulnerability, such as the ease of exploitation, the potential impact on confidentiality, integrity, and availability, and the level of user interaction required to exploit the vulnerability.

CVSS provides a numerical score that ranges from 0 to 10, with 10 representing the most severe vulnerabilities. The score can help security professionals and system administrators prioritize their efforts to address vulnerabilities and allocate resources to address the most critical issues first. CVSS is widely used by security researchers, vendors, and organizations to evaluate the risk posed by different types of vulnerabilities and develop mitigation strategies to protect against them.

 What are the different scores inside CVSS?

CVSS (Common Vulnerability Scoring System) has three versions: CVSSv1, CVSSv2, and CVSSv3. The most recent version is CVSSv3, which provides a more comprehensive and flexible scoring system than the previous versions. CVSSv3 scores vulnerabilities on three different levels:

1. Base Score: This score is determined based on the characteristics of a vulnerability and is intended to represent the intrinsic qualities of the vulnerability itself, independent of any specific environment or context. The Base Score ranges from 0.0 to 10.0, with higher scores indicating more severe vulnerabilities.
2. Temporal Score: This score reflects the current state of the vulnerability, taking into account factors such as the availability of a patch, the level of active exploitation, and the availability of other mitigations. The Temporal Score ranges from 0.0 to 10.0.
3. Environmental Score: This score reflects the potential impact of a vulnerability in a specific environment or context, taking into account factors such as the type of system or application, the level of access controls in place, and the potential business impact of an attack. The Environmental Score ranges from 0.0 to 10.0.

Each score is calculated based on a set of metrics that evaluate different aspects of a vulnerability, such as the attack vector, attack complexity, authentication requirements, confidentiality impact, integrity impact, and availability impact. By using these metrics, CVSS provides a standardized method for assessing the severity of vulnerabilities and helps organizations prioritize their efforts to mitigate them.

What are the versions in CVSS?

The Common Vulnerability Scoring System (CVSS) is a framework for assessing the severity of security vulnerabilities in computer systems. One important aspect of CVSS is the versioning system used to classify the severity of vulnerabilities.

CVSS versioning is based on a scale of 0 to 10, where 0 represents no impact and 10 represents the most severe impact. There are currently three versions of CVSS: CVSSv2, CVSSv3.0, and CVSSv3.1. Here is an overview of each version:

1. CVSSv2: CVSSv2 was released in 2007 and is the oldest version of the framework. It contains three metric groups: base, temporal, and environmental. The base metrics are used to determine the intrinsic severity of a vulnerability, while the temporal metrics take into account factors that may change over time, such as exploit availability or remediation level. Environmental metrics are used to determine the impact of a vulnerability in a specific environment. CVSSv2 scores range from 0 to 10.
2. CVSSv3.0: CVSSv3.0 was released in 2015 and introduced several changes to the framework. It contains two metric groups: base and environmental. The base metrics are similar to those in CVSSv2, but with some changes to improve accuracy. The environmental metrics are used to determine the impact of a vulnerability in a specific environment, just like in CVSSv2. One of the significant changes in CVSSv3.0 is the introduction of a new metric group called attack vector, which includes six possible values that reflect the ease or difficulty of exploiting a vulnerability. CVSSv3.0 scores range from 0 to 10.
3. CVSSv3.1: CVSSv3.1 was released in 2019 and is the latest version of the framework. It includes several updates and improvements over CVSSv3.0, such as additional metric values and new formulas for calculating scores. One of the significant changes in CVSSv3.1 is the introduction of the scope metric, which is used to determine whether a vulnerability affects only a specific component or the entire system. CVSSv3.1 scores range from 0 to 10.

In summary, CVSS provides a standardized method of assessing the severity of vulnerabilities in computer systems. The three versions of the framework provide a range of metrics and scores that allow security professionals to evaluate the potential impact of vulnerabilities on their systems.

Difference in CVSS 3 and CVSS 3.1

The Common Vulnerability Scoring System (CVSS) is a widely used framework for assessing the severity of security vulnerabilities. The latest version of the CVSS framework is CVSS version 3.1, which was released in 2019. While CVSS 3 and CVSS 3.1 share many similarities, there are some important differences between the two versions. Here are a few key differences:

1. Scope: One of the most significant differences between CVSS 3 and CVSS 3.1 is the definition of the "scope" metric. In CVSS 3, the scope metric only takes into account the impact of the vulnerability on the target system. In CVSS 3.1, the scope metric also considers the potential impact of the vulnerability on other systems that are connected to the target system. This change reflects the growing importance of supply chain security and the need to consider the broader impact of security vulnerabilities.
2. Attack Complexity: CVSS 3.1 includes a new metric called "Attack Complexity," which replaces the "Attack Vector" metric in CVSS 3. The Attack Complexity metric considers the level of skill or knowledge required by an attacker to exploit the vulnerability. This change reflects the fact that the complexity of an attack is an important factor in determining the overall risk posed by a vulnerability.
3. Exploit Code Maturity: CVSS 3.1 also includes a new metric called "Exploit Code Maturity," which reflects the level of maturity of any known exploits for the vulnerability. This metric considers factors such as the availability of exploit code, the reliability of the exploit code, and the existence of any mitigations or countermeasures that can reduce the risk posed by the vulnerability.
4. Privileges Required: The Privileges Required metric in CVSS 3.1 has been expanded to include three distinct levels: None, Low, and High. In CVSS 3, the Privileges Required metric only had two levels: None and Low. This change reflects the fact that the level of privileges required by an attacker to exploit a vulnerability can have a significant impact on the overall risk posed by the vulnerability.
5. Base Score Calculation: Finally, the way in which the Base Score is calculated in CVSS 3.1 has been revised to better reflect the impact of vulnerabilities on modern systems and networks. The new Base Score formula takes into account a wider range of factors, including the impact of the vulnerability on confidentiality, integrity, and availability, as well as the impact of any mitigations or workarounds that can reduce the risk posed by the vulnerability.

CVSS Metrics: Base Score, Temporal Score, and Environmental Score

 1.Base Score Metrics: The Base Score Metrics are the intrinsic characteristics of a vulnerability that do not change over time. The Base Score Metrics are used to calculate the Base Score, which reflects the inherent risk posed by a vulnerability. There are six Base Score Metrics in CVSS:

• Attack Vector (AV): This metric describes how the vulnerability is exploited. For example, is it exploited over a network or requires physical access?
• Attack Complexity (AC): This metric describes the level of knowledge or expertise required to exploit the vulnerability. For example, does it require special tools or techniques?
• Privileges Required (PR): This metric describes the level of privileges an attacker needs to exploit the vulnerability. For example, does the attacker need administrative access or can they exploit the vulnerability as a regular user?
• User Interaction (UI): This metric describes the level of user interaction required to exploit the vulnerability. For example, can the vulnerability be exploited without any user interaction or does it require the user to perform an action, such as clicking a link?
• Scope (S): This metric describes the extent of the impact of the vulnerability on the affected system. For example, does it affect only a single user or can it affect the entire system?
• Confidentiality, Integrity, and Availability (CIA) Impact: This metric describes the impact of the vulnerability on the confidentiality, integrity, and availability of the affected system.

Each of these metrics is assigned a value that reflects its severity, with higher values indicating higher severity.

 2.Temporal Score Metrics: The Temporal Score Metrics capture contextual information that can change over time, such as the availability of a patch or the maturity of exploit code. The Temporal Score Metrics are used to calculate the Temporal Score, which reflects the current risk posed by a vulnerability. There are three Temporal Score Metrics in CVSS:

• Exploit Code Maturity (E): This metric describes the level of maturity of exploit code for the vulnerability. For example, is there proof-of-concept code available or are there active exploits in the wild?
• Remediation Level (RL): This metric describes the level of remediation that is currently available for the vulnerability. For example, is a patch available or is the vulnerability unpatched?
• Report Confidence (RC): This metric describes the level of confidence in the existence of the vulnerability. For example, is the vulnerability confirmed or only suspected?

Each of these metrics is assigned a value that reflects its severity, with higher values indicating higher severity.

 3.Environmental Score Metrics: The Environmental Score Metrics describe the characteristics of the system on which the vulnerability exists. The Environmental Score Metrics are used to calculate the Environmental Score, which reflects the risk posed by a vulnerability in a specific environment. There are two Environmental Score Metrics in CVSS:

• Confidentiality, Integrity, and Availability (CIA) Requirements: This metric describes the importance of the affected CIA triad components to the organization. For example, is the confidentiality of the data critical to the organization or is it less important?
• Modified Base Score (MBS): This metric adjusts the Base Score to reflect the characteristics of the environment in which the vulnerability exists. For example, if the vulnerability only affects a non-critical system, the MBS may be lower than the Base Score.

Each of these metrics is assigned a value that reflects its severity, with higher values indicating higher severity.

why should security consulting companies follow CVSS

The Common Vulnerability Scoring System (CVSS) is a framework used to assess the severity of security vulnerabilities in computer systems and networks. Security consulting companies should follow CVSS because it provides a standardized way of evaluating the risk associated with a particular vulnerability. Here are a few reasons why:

1. Consistency: CVSS provides a consistent and objective way of assessing the severity of vulnerabilities. This allows security consulting companies to compare and prioritize vulnerabilities across different systems and networks, ensuring that the most critical vulnerabilities are addressed first.
2. Prioritization: By using CVSS, security consulting companies can prioritize vulnerabilities based on their severity and potential impact. This helps organizations focus their resources on the vulnerabilities that pose the greatest risk to their operations.
3. Communication: CVSS provides a common language for communicating the severity of vulnerabilities to stakeholders. This includes IT staff, executives, and other decision-makers who may not have a deep understanding of technical security issues. By using a standardized framework like CVSS, security consulting companies can ensure that everyone is on the same page when it comes to assessing and addressing security risks.
4. Efficiency: By following CVSS, security consulting companies can streamline their vulnerability assessment processes. This can help them identify and prioritize vulnerabilities more quickly, reducing the time it takes to remediate security issues and minimizing the risk of a successful cyberattack.
5. Compliance: Many regulatory frameworks and industry standards require organizations to assess and address vulnerabilities in their systems and networks. By following CVSS, security consulting companies can ensure that they are meeting these requirements in a consistent and standardized way.

Examples and Evidence:

Example1: Vulnerability Assessment and Scoring Tools Vulnerability assessment and scoring tools, such as Nessus and Qualys, use the CVSS score to assess the severity of vulnerabilities. These tools generate reports that show the CVSS score for each vulnerability, allowing security teams to prioritize their remediation efforts based on the severity of the vulnerabilities.

Evidence: The use of CVSS scores in vulnerability assessment tools has become a common practice in the cybersecurity industry. For example, the 2020 Gartner Magic Quadrant for Vulnerability Assessment rated multiple vendors based on their ability to integrate with CVSS scoring.

Example2: Cybersecurity Incident Response In the event of a cybersecurity incident, security teams can use the CVSS score to help determine the severity of the incident and prioritize their response efforts. The CVSS score can also be used to communicate the severity of the incident to stakeholders, such as executives or customers.

Evidence: The U.S. Cybersecurity and Infrastructure Security Agency (CISA) recommends using the CVSS score as part of incident response procedures. In its publication "Best Practices for Preventing and Handling Ransomware," CISA recommends using the CVSS score to help determine the severity of the incident and prioritize response efforts.

Example3: Compliance and Risk Management Many regulatory frameworks and industry standards require organizations to assess and address vulnerabilities in their systems and networks. The CVSS score can be used to help organizations meet these requirements by providing a standardized way of assessing and prioritizing vulnerabilities.

Evidence: The Payment Card Industry Data Security Standard (PCI DSS) requires organizations to identify and prioritize vulnerabilities based on risk. The CVSS score is listed as one of the factors that organizations should consider when assessing vulnerability risk in the PCI DSS standard.

Examples of how cvss is calculated:

SQL Injection Vulnerability: Suppose a security researcher discovers a SQL injection vulnerability in a web application. The vulnerability allows an attacker to execute arbitrary SQL commands on the backend database, potentially accessing sensitive data or modifying the database. Using CVSS, the vulnerability could be scored as follows:

• Base Score: 9.8 (CVSS score for a SQL injection vulnerability with high impact)
• Temporal Score: 6.5 (CVSS score for a vulnerability that can be easily exploited and has a known exploit in the wild)
• Environmental Score: 4.2 (CVSS score for a vulnerability that affects a low-impact system)

The overall CVSS score for this vulnerability would be 8.2 (weighted average of the base, temporal, and environmental scores).

Cross-Site Scripting (XSS) Vulnerability: Let's say a security analyst discovers a cross-site scripting vulnerability in a web application that allows an attacker to inject malicious JavaScript code into a website. This vulnerability could be scored using CVSS as follows:

• Base Score: 6.1 (CVSS score for a cross-site scripting vulnerability with medium impact)
• Temporal Score: 3.9 (CVSS score for a vulnerability that requires user interaction to exploit)
• Environmental Score: 2.5 (CVSS score for a vulnerability that affects a low-impact system)

The overall CVSS score for this vulnerability would be 4.8.

Privilege Escalation Vulnerability: Suppose a security researcher discovers a privilege escalation vulnerability in an operating system that allows an attacker to gain administrative access to the system. This vulnerability could be scored using CVSS as follows:

• Base Score: 7.8 (CVSS score for a privilege escalation vulnerability with high impact)
• Temporal Score: 5.3 (CVSS score for a vulnerability that can be exploited remotely)
• Environmental Score: 3.2 (CVSS score for a vulnerability that affects a high-impact system)

The overall CVSS score for this vulnerability would be 6.5.

These are just a few examples of how CVSS can be used to calculate the severity of different vulnerabilities. By using a standardized scoring system like CVSS, security professionals can more effectively prioritize and manage security risks.

Conclusion:

In conclusion, the Common Vulnerability Scoring System (CVSS) provides a standardized framework for assessing the severity of security vulnerabilities in computer systems and networks. By assigning a numerical score to each vulnerability, CVSS allows security professionals to prioritize and address vulnerabilities based on their potential impact. CVSS takes into account various factors such as the exploitability of the vulnerability, the impact on confidentiality, integrity, and availability, and the availability of mitigation measures. By following CVSS, security companies can streamline their vulnerability assessment processes and communicate more effectively with stakeholders about their security posture.

At digiALERT, we understand the importance of CVSS scoring in assessing and addressing security risks. We use CVSS as part of our vulnerability assessment process to evaluate the severity of security vulnerabilities and prioritize remediation efforts. Our team of security professionals has extensive experience in working with CVSS and other security frameworks to help our clients manage their security risks effectively. By following best practices and industry standards, including CVSS scoring, we help our clients stay ahead of the evolving threat landscape and protect their assets and data from cyber attacks.