Vulnerability management plays a crucial role in all effective cybersecurity programs. Security teams face an overwhelming number of reported vulnerabilities because many reports prove to be false positives or non-exploitable in their specific environment. Security teams spend countless hours investigating vulnerabilities that pose little to no actual risk. The blog post demonstrates how to minimize time wasted on false positives by focusing on reachability and exploitability and using exceptions and suppression lists effectively.
1. The process of CVE Reporting faces the significant challenge of false positive results.
Organizations regularly conduct vulnerability scans on their systems and software, leading modern scanning tools to generate extensive lists of Common Vulnerabilities and Exposures (CVEs). Comprehensive coverage is essential but it creates a major challenge.
- Volume of detections: Each scan usually results in the discovery of hundreds to thousands of potential vulnerabilities.
- False positives: Certain vulnerabilities receive a “critical” rating despite their non-exploitability in the organization’s environment which results in squandered time.
- Repetitive triaging: Different systems or software versions often show the same or similar false positives multiple times.
- If security teams devote excessive time to non-threatening issues they will likely overlook the organization’s most important vulnerabilities.
2. Understanding Reachability
Reachability determines if a vulnerability can be accessed and triggered within your specific environment. There may be underlying code vulnerabilities that cannot be activated within actual operating conditions. For example:
- The application may not use the vulnerable function.
- Network segmentation may protect a service or it could be disabled.
- Specific settings or permission levels may block attackers from taking advantage of the vulnerability.
Assessing reachability allows you to allocate resources more effectively between patching or investigating potential issues. Reachability typically involves:
- Code Review or Dependency Analysis: Check whether the vulnerable function or dependency gets executed or loads into memory during runtime.
- Network Architecture: Check for the accessibility of the vulnerable component across the network and ensure it can be accessed especially from untrusted areas.
- Configuration Checks: Inspect system settings and permissions along with feature flags to determine if they disable the vulnerability.
- If a vulnerability cannot be reached during evaluation, teams may choose to deprioritize it, suppress it from upcoming scans, or record it as a recognized non-exploitable problem.
3. Leveraging Exploitability with KEV and EPSS
Even when a vulnerability is accessible, you must evaluate its potential to be exploited. The Known Exploited Vulnerabilities (KEV) catalog from CISA and FIRST’s Exploit Prediction Scoring System (EPSS) become crucial in this evaluation process.
3.1 Known Exploited Vulnerabilities (KEV)
What is KEV?
CISA maintains the KEV catalog which details all vulnerabilities currently exploited in active attacks.
How to use KEV:
The inclusion of a CVE in the KEV catalog represents an urgent warning sign. Security teams must focus on reviewing and remediating these vulnerabilities first since threat actors are known to be targeting them.
3.2 Exploit Prediction Scoring System (EPSS)
What is EPSS?
The Forum of Incident Response and Security Teams (FIRST) created EPSS which offers a data-driven probability that a specific vulnerability will be exploited within 30 days.
How to use EPSS:
Security teams should integrate EPSS scores into their vulnerability management processes. Vulnerabilities with higher EPSS scores demonstrate an increased probability of being exploited. A comprehensive risk assessment emerges from merging CVSS severity scores with EPSS exploit probability scores.
By combining reachability data with exploitability scores (KEV, EPSS), security teams can prioritize their efforts more effectively. When a vulnerability exists within your environment and attackers actively exploit it in real-world scenarios it requires immediate attention while vulnerabilities that are inaccessible and show very low EPSS scores can be assigned lower priority levels.
4. Effective Use of Exceptions and Suppression Lists
Despite having solid prioritization methods that consider reachability and exploitability levels, security teams might find vulnerabilities which do not require immediate resolution upon each scan. Organizations can use exceptions and suppression lists to optimize their vulnerability management processes when facing specific scenarios.
4.1 Exceptions
An exception represents formal consent to delay vulnerability remediation for a specific period. This can be based on:
- Business Impact: The process of patching or upgrading systems can produce operational risks which may surpass the security advantages.
- Compensating Controls: The risk of exploitation can be mitigated through alternative security measures such as strict network segmentation and intrusion detection systems.
- Non-Exploitable State: If the vulnerability remains inaccessible it loses its impact.
Key considerations:
- Review Period: Exceptions should include expiration dates which require regular reviews to ensure that the associated risk remains unchanged.
- Documentation: Maintaining compliance alongside accountability requires documentation of justification and approval authority together with review dates.
4.2 Suppression Lists
Although exceptions must have expiration dates with justifications, suppression lists provide a way to permanently filter out vulnerabilities that are repeatedly identified but assessed as non-risky or false positives.
- Permanent Suppression: The permanent suppression category includes vulnerabilities that have been conclusively identified as false positives or unreachable.
- Conditional Suppression: Conditional suppression applies to vulnerabilities that stay unexploited as long as specific conditions continue to exist (such as when a non-default feature remains turned off).
Key considerations:
- Regular Re-validation: Carry out regular audits of the suppression list to ensure that the conditions which justified the suppressions remain unchanged. This process ensures that recognized problems stay visible even as the environment undergoes changes.
- Controlled Access: The ability to modify the suppression list should be restricted to specific users to prevent misuse.
5. Reducing Time Spent on False Positives
Security teams that merge reachability analysis with exploitability data (KEV, EPSS) and efficient exception/suppression management observe a substantial reduction in time spent investigating false positives. Here’s how:
5.1 Automated Triage
Security teams can configure automated tools to match vulnerabilities against KEV or EPSS scores. Vulnerabilities absent from KEV and showing low EPSS scores should be deprioritized unless strong evidence indicates they are exploitable in your particular environment.
5.2 Streamlined Workflow
Applying exceptions to non-critical cases prevents security teams from repeatedly analyzing false positives. Security teams can prioritize genuine threats instead of redoing identical analyses.
5.3 Consistent Documentation
Documenting the reasons behind a vulnerability being unreachable or having low exploit potential prevents future repetitive evaluations of the same issues. The maintained history eliminates redundant work and guides subsequent decision-making processes.
5.4 Better Communication
Security teams can clearly explain to stakeholders such as auditors and management why they have not patched specific vulnerabilities through a structured exception and suppression process. By being transparent you build stakeholder trust and demonstrate that you are appropriately prioritizing threats instead of ignoring them.
Conclusion
Proper handling of CVE false positives requires informed decisions to identify real threats instead of simply overlooking potential problems. Security teams can identify genuine threats more effectively by analyzing reachability assessments alongside exploitability metrics (KEV and EPSS). Using suppression lists and exceptions makes sure that non-actionable vulnerabilities do not waste time in future scans.
Ultimately, the goal is to allocate finite security resources where they matter most: Your organization needs to focus on securing critical assets while stopping actual exploitation attempts. Implementing smart prioritization together with managed processes for dealing with false positives enables you to uphold strong security without becoming overwhelmed by excessive alerts.
About OpsMx
OpsMx is a leading innovator and thought leader in the Application Security space. Leading technology companies such as Google, Cisco, Western Union, among others rely on OpsMx to secure their application lifecycle.
OpsMx Secure CD is the industry’s first CI/CD solution designed for software supply chain security. With built-in compliance controls, automated security assessment, and policy enforcement, OpsMx Secure CD can help you deliver software quickly without sacrificing security.
OpsMx Delivery Shield adds DevSecOps capabilities to enterprise deployments by providing Application Security Posture Management (ASPM), unified visibility, compliance automation, and security policy enforcement to your existing application lifecycle.
0 Comments