CVE-2016-7099 in Node.js
Summary
by MITRE
The tls.checkServerIdentity function in Node.js 0.10.x before 0.10.47, 0.12.x before 0.12.16, 4.x before 4.6.0, and 6.x before 6.7.0 does not properly handle wildcards in name fields of X.509 certificates, which allows man-in-the-middle attackers to spoof servers via a crafted certificate.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability described in CVE-2016-7099 represents a critical flaw in Node.js's SSL/TLS certificate validation mechanism that has significant implications for secure communications. This issue affects multiple major versions of the Node.js runtime environment, specifically targeting the tls.checkServerIdentity function that is responsible for verifying server certificates during TLS handshakes. The flaw stems from improper handling of wildcard characters within the subject alternative name fields of X.509 certificates, creating a pathway for attackers to exploit the certificate validation process.
The technical root cause of this vulnerability lies in the insufficient validation of wildcard patterns within certificate name fields, which violates established security principles for certificate verification. When Node.js processes X.509 certificates containing wildcards, the function fails to properly validate that the wildcard pattern correctly matches the actual hostname being connected to. This allows attackers to craft certificates where wildcard patterns in the certificate do not align with the intended server identity, yet the validation function still accepts them as valid. The vulnerability specifically impacts the subject alternative name extension of certificates, which is a critical component of modern SSL/TLS implementations according to x509 certificate standards.
This flaw creates a significant man-in-the-middle attack vector that can be exploited by malicious actors to impersonate legitimate servers without detection. An attacker with access to create or modify certificates can generate a certificate that contains a wildcard pattern matching a domain name, but where the actual server being impersonated is different from what the certificate should represent. The attack works because the validation function does not properly enforce the constraints that wildcards should only match subdomains of the certificate's intended domain, allowing for broader matching patterns that could include entirely different domains. This vulnerability directly relates to CWE-295, which addresses improper certificate validation, and aligns with ATT&CK technique T1071.004 for application layer protocol traffic manipulation.
The operational impact of this vulnerability extends across numerous Node.js applications that rely on secure TLS connections, potentially affecting web services, API endpoints, and any system that uses Node.js for HTTPS communication. Organizations using affected Node.js versions face the risk of their applications being compromised through certificate spoofing attacks, where attackers can intercept and modify communications between clients and servers. The vulnerability affects not just individual applications but entire ecosystems built on Node.js, as the flaw exists within the core TLS validation library that is used by countless applications. The widespread nature of Node.js usage means that this vulnerability could potentially impact hundreds of thousands of systems globally, making it a high-priority security concern for organizations maintaining web infrastructure.
Mitigation strategies for CVE-2016-7099 require immediate patching of affected Node.js versions to the latest stable releases that contain the corrected certificate validation logic. Organizations should prioritize upgrading to Node.js 0.10.47, 0.12.16, 4.6.0, or 6.7.0 respectively, as these versions contain the necessary fixes for wildcard certificate validation. Additionally, security teams should implement monitoring for suspicious certificate usage patterns and consider implementing additional certificate validation layers beyond the default Node.js functionality. The fix implemented in these patched versions ensures proper handling of wildcard patterns in certificate subject alternative name fields, enforcing stricter matching rules that prevent the bypass conditions exploited by attackers. Organizations should also conduct thorough security assessments of their Node.js applications to identify any custom certificate validation logic that might be susceptible to similar issues and ensure that all systems are updated to versions that properly address this CVE.