In the broad expanse of the digital realm, where hazards lurk around every virtual corner, having a reliable standard is critical. Common Vulnerability Scoring System (CVSS) serves as a standard for scoring, prioritizing, and mitigating vulnerabilities based on their likelihood of being attacked and the impact they would have on organizations if attacked successfully. Its purpose is to evaluate and communicate information regarding the seriousness of vulnerabilities in security across networks and computer systems. It provides a standardized method for evaluating and prioritizing vulnerabilities, helping effectively to manage and address potential threats. In regards to Software as a Medical Device (SaMD), CVSS serves as a method of assigning scores to security vulnerabilities to rank them in order of severity. The main technical features of vulnerabilities found in software, hardware, and firmware are recorded in CVSS.
With the introduction of version 1 in 2005, CVSS has undergone changes throughout time; having the latest version as CVSS version 4.0. The system is maintained by the Forum of Incident Response and Security Teams (FIRST).
The score assigned to a vulnerability using CVSS guidelines ranges from 0 to 10, depending on the metrics evaluated while analyzing the vulnerability. This score indicates the level of severity of vulnerability having low risk at 1 to critical risk at 10.
The Common Vulnerability Scoring System (CVSS) is a standardized framework for assessing the severity of software vulnerabilities. It provides a numerical score (0–10) based on exploitability, impact, and environmental factors, helping organizations prioritize and address security risks effectively. CVSS is widely used for vulnerability management and risk assessment.
CVSS comprises four metric groups: Base, Threat, Environmental, and Supplemental.
Since the base metric provides fundamental analysis of intrinsic characteristics, this metric forms the foundation for calculating CVSS score. Hence, here we will be discussing the same in detail:
The Threat metrics in the Common Vulnerability Scoring System (CVSS) evaluate the dynamic aspects of a vulnerability, focusing on its potential exploitation and the current threat landscape. These metrics consider factors such as active exploitation in the wild, availability of exploit tools, and the sophistication required to exploit the vulnerability. Unlike static metrics like the Base group, Threat metrics are highly variable, reflecting real-time intelligence. This helps organizations assess the urgency of mitigation efforts by understanding how likely and imminent an attack is. While not a core CVSS component, threat metrics enhance risk assessment and prioritization in cybersecurity strategies.
The Environmental metrics in the Common Vulnerability Scoring System (CVSS) assess the specific impact of a vulnerability within an organization’s unique context. These metrics consider factors like the criticality of affected systems, the sensitivity of data, and the presence of mitigating controls in the environment. Unlike Base metrics, which are static, Environmental metrics are customizable, allowing organizations to adjust scores based on their risk tolerance and business priorities. By incorporating these metrics, CVSS enables tailored vulnerability assessments, helping organizations prioritize remediation efforts effectively based on their operational environment and the potential impact on their specific assets.
The Supplemental metrics in the Common Vulnerability Scoring System (CVSS) provide additional, non-mandatory information to enhance vulnerability assessments. These metrics address factors not covered in the Base, Threat, or Environmental groups, such as the vulnerability’s exploit code maturity, potential societal impact, or additional technical details. Supplemental metrics are designed to offer context-specific insights, aiding organizations in refining their risk evaluations. While not officially included in CVSS scoring calculations, they can be valuable for stakeholders needing deeper analysis or broader considerations, such as compliance, reputation risk, or long-term planning for cybersecurity strategies.
Scenario: The medical image processing software utilizes VirtualBox as its platform to host and manage virtual machines (VMs). These VMs are responsible for storing sensitive medical images and patient data. However, a vulnerability has been discovered in VirtualBox that could be exploited by an attacker with high privileges on the virtualization infrastructure.
Explanation: The medical image processing software relies on VirtualBox as its platform to manage VMs, which are used to store sensitive medical images and patient data. A vulnerability has been identified in VirtualBox which could potentially allow an attacker to exploit flaws in security mechanisms, enabling them to gain unauthorized access to the underlying infrastructure. The attacker in this scenario possesses high privileges on the virtualization infrastructure where VirtualBox is executed. This means that they have elevated access rights, potentially allowing them to gain unauthorized access to critical data like sensitive medical images, patient records, diagnostic information, and other confidential healthcare data.
CVSS score will be 5.9 which has associated severity rating of Medium and CVSS-B metric scoring for the same will be:
METRIC | VALUE | COMMENTS |
Attack Vector | Local | An attacker must be able to access the vulnerable system with a local, interactive session. |
Attack Complexity | Low | No specialized conditions or advanced knowledge are required. |
Attack Requirements | None | No attack requirements are present. |
Privileges Required | High | An attacker must have administrative control over a virtual machine within the virtual machine host. |
User Interaction | None | No user interaction is required for an attacker to successfully exploit the vulnerability. |
Vulnerable System Confidentiality | None | There is no impact to the vulnerable system confidentiality. |
Vulnerable System Integrity | None | There is no impact to the vulnerable system integrity. |
Vulnerable System Availability | None | There is no impact to the vulnerable system availability. |
Subsequent System Confidentiality | High | An attacker could exploit this vulnerability to access confidential information stored within the VM host hypervisor system. |
Subsequent System Integrity | None | There is no impact to subsequent systems. |
Subsequent System Availability | None | There is no impact to subsequent systems. |
Thus, overall CVSS provides consumer detailed information to understand the amount of risk associated with vulnerabilities and helps to prioritize vulnerabilities. This way, they can protect their systems and data better from cyber threats.
Common Vulnerability Scoring System version 4.0: Specification Document
Author – Fatimah Narmawala
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