Definition
The Common Vulnerability Scoring System (CVSS) Score is a standardized method for evaluating the severity of security vulnerabilities in software. It assigns a numerical score from 0 to 10, with higher scores indicating more severe vulnerabilities.How It Works
- 1Base Metrics: These capture the inherent qualities of a vulnerability, such as its impact and how easily it can be exploited.
- 2Temporal Metrics: These adjust the base score based on factors that change over time, like the availability of exploits or patches.
- 3Environmental Metrics: These modify the score based on the specific environment, considering the importance of affected IT assets.
- 4Severity Ratings: CVSS scores translate into severity ratings: None (0.0), Low (0.1-3.9), Medium (4.0-6.9), High (7.0-8.9), and Critical (9.0-10.0).
Key Characteristics
- Scalable: Applicable to any vulnerability across systems.
- Structured: Uses three metric groups (Base, Temporal, Environmental) for thorough assessment.
- Version Updates: CVSS v3.1 offers refined metrics compared to v2.
Comparison
| Aspect | CVSS v2 | CVSS v3.1 |
|---|---|---|
| Metric Groups | Base, Temporal, Environmental | Base, Temporal, Environmental |
| Scoring Precision | Less granular | More granular |
| Severity Ratings | Less nuanced | More nuanced |
Real-World Example
CVE-2021-44228, known as Log4Shell, received a CVSS v3.1 score of 10.0, highlighting its critical nature due to easy exploitation and severe impact on confidentiality, integrity, and availability.Detection & Prevention
- Tools: Utilize nmap, Burp Suite, and OWASP ZAP to detect vulnerabilities.
- Patching: Prioritize patches based on CVSS scores.
- Environment Assessment: Regularly assess environmental changes affecting vulnerability severity.
Common Misconceptions
- Myth 1: "A high CVSS score means immediate exploitation." Not all high-scoring vulnerabilities are actively exploited.
- Myth 2: "CVSS scores are static." Scores can change with new information or environmental changes.
- Myth 3: "CVSS scores alone dictate patching priorities." Business impact and asset value should also be considered.