Full Report
Rising vulnerability reports and an increasing backlog of critical vulnerabilities and exposures (CVE) conspire to put companies at risk. The new NIST Likely Exploited Vulnerabilities (LEV) metric can help.
Analysis Summary
# Regulation/Compliance: Adoption of NIST Likely Exploited Vulnerabilities (LEV) Metric for Prioritization
## Overview
This summary focuses on the introduction of the National Institute of Standards and Technology (NIST) **Likely Exploited Vulnerabilities (LEV)** metric, a proposed method designed to help organizations manage the growing backlog of Critical Vulnerabilities and Exposures (CVEs) by focusing remediation efforts on vulnerabilities with the highest immediate risk profile.
## Key Details
- Issuing Authority: National Institute of Standards and Technology (NIST)
- Effective Date: The LEV metric is proposed and its implementation is dependent on the adoption and integration by organizations. The context references a "new metric" and a final whitepaper, suggesting it is available for immediate use or near-term integration.
- Jurisdiction: Primarily frameworks and standards guidance for U.S. federal agencies and any organization voluntarily implementing NIST standards, though highly influential globally.
- Status: Proposed/Published Guidance (As a formal metric within a NIST publication).
## Requirements
### Mandatory Requirements
*The LEV metric itself is a **guidance/recommendation** rather than a mandatory regulation. However, if an organization is mandated to follow specific NIST risk management frameworks (like those required by US Federal Executive Orders or subsequent agency directives), incorporating LEV for remediation prioritization may become implicitly required.*
1. **Integration of LEV Data:** Utilize the LEV calculated data (probability of past exploitation, matched CPEs) to inform vulnerability remediation prioritization decisions.
2. **Continuous Monitoring:** Integrate daily LEV updates into the vulnerability management process.
### Recommended Practices
1. **Supplemental Use:** Employ LEV data in conjunction with the CISA Known Exploited Vulnerabilities (KEV) catalog and the Exploit Prediction Scoring System (EPSS) for a comprehensive risk assessment.
2. **Contextual Analysis:** Do not rely solely on LEV/KEV scores; perform contextual analysis to determine if listed vulnerabilities are technically exploitable or specifically relevant to the organization's deployed software/code inventory (CPEs).
3. **Proactive Posture:** Use the predictive elements of $\mathrm{LEV}$ to move beyond reactive patching toward proactive cybersecurity defense.
## Affected Organizations
- Industries: All organizations engaged in robust vulnerability management, particularly those managing critical infrastructure or those adhering to US government security mandates (e.g., defense industrial base, federal contractors).
- Organization Size: Not explicitly defined by size, but highly relevant to organizations processing large volumes of CVEs.
- Geographic Scope: Primarily US-centric guidance, but influential worldwide.
## Compliance Timeline
- **Initial Release/Publication:** The LEV whitepaper is published, detailing the formula and data outputs.
- **Recommendation Timeliness:** Organizations are recommended to begin integrating LEV calculations immediately, as the LEV provides **daily updates**.
- **Final Deadline:** Not applicable, as this is a guidance metric for risk-based remediation prioritization, not a mandated compliance deadline.
## Implementation Guidance
### Assessment Phase
- **Gap Analysis:** Assess current vulnerability prioritization methods against a baseline that includes KEV and EPSS. Determine the gap in utilizing *historical and likely exploitation probability*.
- **Inventory Mapping:** Ensure a robust, current inventory of software and code (using CPEs) exists to effectively map listed LEV findings to internal assets.
### Implementation Phase
- **Data Ingestion:** Establish an automated mechanism to ingest and process the daily LEV output data streams.
- **Prioritization Integration:** Modify existing patch management workflows to use the LEV score as a primary factor (alongside severity) when queueing remediation work.
### Validation Phase
- **Effectiveness Measurement:** Measure the reduction in time-to-remediate for vulnerabilities identified via LEV compared to those identified only by CVSS scoring.
- **Cross-Validation:** Validate LEV findings against internal penetration testing results or threat intelligence feeds to confirm prioritization accuracy.
## Technical Requirements
1. **Data Output:** The LEV calculation provides: CVE name/description, Probability of past exploitation, Maximum EPSS score windows, and a list of affected software/code via **Common Product Enumeration (CPE)**.
2. **Correlation:** Requires the ability to correlate LEV findings with existing vulnerability scanner data and asset management systems via CPE matching.
## Penalties & Enforcement
- Fines: **None directly associated with the LEV metric itself**, as it is a risk management standard guidance, not a legal mandate.
- Other Consequences: Failing to prioritize known-exploited or highly likely-to-be-exploited vulnerabilities (as flagged by derivative sources like KEV or LEV) could lead to increased incident response costs, reputational damage, and potential liability if regulatory bodies (like CISA or SEC) cite failure to adopt industry best practices after an incident.
- Enforcement: Enforcement pathways would apply if an organization is found non-compliant with a higher-level regulation (e.g., FedRAMP, HIPAA, or sector-specific rules) that explicitly mandates adoption of NIST guidelines for risk management.
## Related Standards
- **Common Vulnerabilities and Exposures (CVE):** The base data structure upon which LEV operates.
- **Known Exploited Vulnerabilities (KEV) Catalog (CISA):** LEV results can be used to measure the comprehensiveness of the KEV list.
- **Exploit Prediction Scoring System (EPSS) (FIRST):** LEV incorporates the maximum EPSS score over selected windows into its final output for richer data.
- **Common Product Enumeration (CPE):** Used to describe the affected software components.
## Resources
- Official Documentation: NIST LEV Whitepaper (Link provided in source context: `https://csrc.nist.gov/pubs/cswp/41/likely-exploited-vulnerabilities-a-proposed-metric/final`)
- Guidance Documents: CISA KEV Catalog documentation; FIRST EPSS documentation.
- Tools: Vulnerability scanners capable of ingesting and correlating CVE, KEV, and EPSS/LEV data points.
## Practical Recommendations
1. **Adopt Daily Intake:** Treat LEV vulnerability data as high-priority input requiring integration into daily threat intelligence feeds.
2. **Focus on High Probability:** Prioritize remediation efforts on assets linked to CVEs showing a high probability of past exploitation as determined by the LEV calculation.
3. **Contextualize KEV:** Use LEV to move beyond simply patching *everything* in the KEV list; use LEV to determine which 1,300 KEV items are most immediately dangerous to *your* specific environment.
4. **Layer Defenses:** Implement advanced detection controls, such as multimodal AI threat detection, to catch sophisticated attacks targeting vulnerabilities that are not yet widely publicized or present in initial public lists.