CVE-2020-15104 : Exploit Details and Defense Strategies

In Envoy before versions 1.12.6, 1.13.4, 1.14.4, and 1.15.0, a TLS validation vulnerability allowed wildcard DNS Subject Alternative Names to apply to multiple subdomains, potentially leading to security risks.

Understanding CVE-2020-15104

This CVE pertains to a vulnerability in Envoy's TLS certificate validation process, impacting specific versions of the software.

What is CVE-2020-15104?

The vulnerability in Envoy allowed wildcard DNS Subject Alternative Names to be incorrectly applied to multiple subdomains, potentially enabling unauthorized access.

The Impact of CVE-2020-15104

CVSS Base Score: 4.6 (Medium Severity)
Attack Vector: Network
User Interaction: Required
Confidentiality Impact: Low
Integrity Impact: Low
Privileges Required: Low
Scope: Unchanged
Attack Complexity: Low
Availability Impact: None

Technical Details of CVE-2020-15104

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The vulnerability allowed wildcard DNS Subject Alternative Names to be incorrectly applied to multiple subdomains in Envoy, potentially compromising the security of TLS certificate validation.

Affected Systems and Versions

Affected Product: Envoy
Vendor: envoyproxy
Vulnerable Versions: < 1.12.6, >= 1.13.0, < 1.13.4, >= 1.14.0, < 1.14.4

Exploitation Mechanism

The vulnerability could be exploited by using a signed wildcard TLS certificate for a domain to gain unauthorized access to subdomains, bypassing intended security measures.

Mitigation and Prevention

To address CVE-2020-15104, follow these mitigation strategies:

Immediate Steps to Take

Update Envoy to versions 1.12.6, 1.13.4, 1.14.4, or 1.15.0, where the issue has been resolved.
Review and update TLS certificate validation configurations to ensure proper validation of Subject Alternative Names.

Long-Term Security Practices

Regularly monitor for security advisories and updates related to Envoy.
Implement strict certificate management practices to prevent unauthorized certificates.

Patching and Updates

Apply patches and updates provided by Envoy to address the vulnerability and enhance overall security.