CVE-2025-27110

Remediation/Mitigation Strategy for CVE-2025-27110

This document outlines the remediation and mitigation strategy for CVE-2025-27110, affecting Libmodsecurity3 version 3.0.13.

1. Vulnerability Description:

  • Vulnerability: In Libmodsecurity3 version 3.0.13, the library is unable to correctly decode encoded HTML entities if they contain leading zeroes (e.g., < instead of <). This means potentially malicious or unintended data could bypass ModSecurity’s inspection, leading to vulnerabilities.
  • Affected Component: Libmodsecurity3
  • Affected Version: 3.0.13

2. Severity:

  • CVSS v3 Score: 8.6 (High)
  • Vector: AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N (Network, Low Attack Complexity, No Privileges Required, No User Interaction, Changed Scope, High Confidentiality, High Integrity, No Availability Impact)
  • Explanation: This vulnerability is rated as high severity because it allows an unauthenticated attacker to potentially bypass ModSecurity’s protections by crafting malicious payloads with HTML entities containing leading zeroes. Successful exploitation could lead to significant impact on the confidentiality and integrity of the protected application. The lack of impact on availability reduces the score slightly, but the potential for data breaches and unauthorized actions remains high.

3. Known Exploits:

  • Exploit Availability: According to the provided information, there are currently no known exploits publicly available. However, the vulnerability itself is understood, and creating a proof-of-concept exploit is relatively straightforward.

4. Remediation Strategy:

  • Primary Remediation: Upgrade Libmodsecurity3 to version 3.0.14 or later. This is the only known permanent fix for the vulnerability. All systems using Libmodsecurity3 version 3.0.13 should be upgraded immediately.

    • Steps:
      1. Identify all systems using Libmodsecurity3 version 3.0.13. This includes web servers, load balancers, and any other systems that incorporate ModSecurity for security purposes.
      2. Plan the upgrade process. Coordinate with application owners and system administrators to schedule a maintenance window for the upgrade. Consider testing the upgrade in a non-production environment first.
      3. Upgrade Libmodsecurity3. Follow the instructions provided by your operating system or package manager to upgrade Libmodsecurity3 to version 3.0.14 or later. This will typically involve using commands like apt-get update && apt-get upgrade libmodsecurity3 (Debian/Ubuntu), yum update libmodsecurity3 (CentOS/RHEL), or similar.
      4. Verify the upgrade. After the upgrade, verify that Libmodsecurity3 is running version 3.0.14 or later by checking the version information using the appropriate command-line tool or configuration file.
      5. Retest affected applications. After the upgrade, thoroughly test the applications that rely on ModSecurity to ensure that they are functioning correctly.

  • Rollback Plan:

    • Document the existing configuration and versioning of all components before the upgrade.
    • Have procedures in place to quickly revert to the previous Libmodsecurity3 version if the upgrade introduces unforeseen issues.

5. Mitigation Strategy (If Immediate Upgrade is Not Possible):

  • While upgrading is the required solution, if an immediate upgrade is impossible, consider the following (limited) mitigation options:

    • Input Sanitization and Validation: Implement strict input sanitization and validation on the application side, before the data reaches ModSecurity. This can help to remove or neutralize HTML entities with leading zeroes before they are processed by Libmodsecurity3. This is not a foolproof solution but can reduce the attack surface. Example include:

      • Rejecting input containing HTML entities with leading zeroes.
      • Converting HTML entities with leading zeroes to their equivalent characters before ModSecurity processes the request.
      • Implement a WAF rule in front of Modsecurity to detect and block payloads containing suspicious HTML entities with leading zeroes.

    • Considerations: These mitigation strategies are not guaranteed to be effective against all possible attack vectors and should be considered temporary measures until Libmodsecurity3 can be upgraded. They may also introduce performance overhead or compatibility issues.

    • Limitations: These approaches are complex to implement correctly and can be easily bypassed. It is vital to upgrade as soon as practically possible.

6. Monitoring and Detection:

  • Monitor ModSecurity logs for suspicious activity: Monitor the ModSecurity logs for attempts to bypass ModSecurity rules using HTML entities with leading zeroes. Look for patterns that indicate malicious activity.

7. Communication:

  • Communicate this vulnerability and the remediation/mitigation steps to all affected teams and stakeholders.
  • Provide regular updates on the progress of the remediation effort.

8. Timeline:

  • Immediate Action: Identify affected systems and begin planning the upgrade process.
  • Short-Term (Within 1 week): Upgrade all affected systems to Libmodsecurity3 version 3.0.14 or later. If an immediate upgrade is not possible, implement the mitigation strategies outlined above.
  • Long-Term: Continuously monitor for new ModSecurity vulnerabilities and apply updates promptly. Review security best practices for input sanitization and validation to prevent similar vulnerabilities in the future.

Disclaimer:

This document provides a general remediation/mitigation strategy for CVE-2025-27110. The specific steps required may vary depending on your environment. Consult with your security team and system administrators to determine the best course of action for your organization. The mitigation strategies are not a substitute for upgrading to a patched version of Libmodsecurity3.

Assigner

Date

  • Published Date: 2025-02-25 20:15:38
  • Updated Date: 2025-02-25 20:15:38

More Details

CVE-2025-27110