CVE-2017-18911:Mattermost Server X.509 Certificate Validation Bypass Vulnerability

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A vulnerability was discovered in Mattermost Server before versions 3.8.2, 3.7.5, and 3.6.7 where the application fails to properly validate X.509 certificates for TLS-based email servers. This could allow attackers to perform man-in-the-middle attacks by bypassing the certificate validation process, potentially intercepting sensitive communications between the Mattermost server and email servers.

Overview

This vulnerability (CVE-2017-18911) is a certificate validation bypass issue (CWE-295) affecting Mattermost Server. The flaw allows the application to skip X.509 certificate validation when connecting to TLS-based email servers. When certificate validation is bypassed, the server cannot verify the authenticity of the email server it's connecting to, which breaks the trust model of TLS. An attacker positioned between the Mattermost server and the email server could intercept, view, or modify email communications without detection. This vulnerability could lead to unauthorized access to sensitive information, including account credentials and email content.

Remediation

To remediate this vulnerability, users should upgrade to the following patched versions:

  • Version 3.8.2 or later if using the 3.8.x branch
  • Version 3.7.5 or later if using the 3.7.x branch
  • Version 3.6.7 or later if using the 3.6.x branch

If immediate patching is not possible, consider implementing the following temporary mitigations:

  1. Restrict network access to email servers to trusted networks only
  2. Implement network-level monitoring to detect potential man-in-the-middle attacks
  3. Consider using alternative methods for email notifications until the system can be patched

System administrators should verify proper certificate validation after upgrading by checking server logs and configuration settings.

References

  1. Mattermost Security Updates: https://mattermost.com/security-updates/
  2. CWE-295: Certificate Validation Issues: https://cwe.mitre.org/data/definitions/295.html
  3. MITRE CVE Entry: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-18911

Industry ExposureMost to least
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.

  1. Accommodation & Food Services
    Accommodation & Food Services
  2. Administrative, Support, Waste Management & Remediation Services
    Administrative, Support, Waste Management & Remediation Services
  3. Agriculture, Forestry Fishing & Hunting
    Agriculture, Forestry Fishing & Hunting
  4. Arts, Entertainment & Recreation
    Arts, Entertainment & Recreation
  5. Construction
    Construction
  6. Educational Services
    Educational Services
  7. Finance and Insurance
    Finance and Insurance
  8. Health Care & Social Assistance
    Health Care & Social Assistance
  9. Information
    Information
  10. Management of Companies & Enterprises
    Management of Companies & Enterprises
  11. Manufacturing
    Manufacturing
  12. Mining
    Mining
  13. Other Services (except Public Administration)
    Other Services (except Public Administration)
  14. Professional, Scientific, & Technical Services
    Professional, Scientific, & Technical Services
  15. Public Administration
    Public Administration
  16. Real Estate Rental & Leasing
    Real Estate Rental & Leasing
  17. Retail Trade
    Retail Trade
  18. Transportation & Warehousing
    Transportation & Warehousing
  19. Utilities
    Utilities
  20. Wholesale Trade
    Wholesale Trade

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  3. Proactively Mitigate Threats.

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