Definition: The Exploit Prediction Scoring System (EPSS) is a predictive model developed to estimate the likelihood that a software vulnerability will be exploited. It is designed by the FIRST.org community and aims to help organizations prioritize vulnerabilities based on the probability of exploitation.
Scoring System Overview:
- EPSS scores are represented as probabilities, ranging from 0 (least likely to be exploited) to 1 (most likely to be exploited).
- The scoring model considers a variety of factors, such as the characteristics of the vulnerability, the nature of the affected software, and historical exploit data.
- EPSS Score Range:
- The scores are presented as decimal values close to 0 for less likely to be exploited vulnerabilities, and closer to 1 for those with a higher likelihood of exploitation.
Importance of EPSS:
- Enhanced Vulnerability Management: Provides a probabilistic approach to vulnerability management, helping organizations prioritize patches based on the likelihood of exploitation.
- Complement to CVSS: While CVSS rates the severity of vulnerabilities, EPSS adds a predictive dimension, estimating the likelihood of exploitation.
- Strategic Resource Allocation: Enables more strategic allocation of security resources, focusing on vulnerabilities more likely to be exploited.
- Predictive Nature: EPSS provides estimations, not guarantees, regarding the likelihood of exploitation.
- Data-Driven Accuracy: The model’s accuracy depends on the quality and quantity of the data it’s trained on, which may evolve over time.
- Contextual Relevance: The relevance and applicability of EPSS scores can vary based on an organization’s specific environment and context.
The Exploit Prediction Scoring System represents a significant advancement in cybersecurity risk management, offering a data-driven, probabilistic approach to prioritize vulnerabilities. While not a definitive predictor, EPSS is a valuable tool that complements the CVSS framework, providing a more rounded understanding of vulnerabilities in terms of both severity and exploitability.