CVE-2016-4467 in Qpid
Summary
by MITRE
The C client and C-based client bindings in the Apache Qpid Proton library before 0.13.1 on Windows do not properly verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate when using the SChannel-based security layer, which allows man-in-the-middle attackers to spoof servers via an arbitrary valid certificate.
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Analysis
by VulDB Data Team • 09/05/2022
The Apache Qpid Proton library vulnerability CVE-2016-4467 represents a critical security flaw in the client-side certificate validation mechanism on Windows platforms. This vulnerability specifically affects the C client and C-based client bindings within the Proton library version 0.13.0 and earlier, where the implementation fails to properly validate SSL/TLS certificates during secure communications. The flaw manifests when using the SChannel-based security layer on Windows operating systems, which is the native Windows security API for handling secure communications. This issue creates a significant attack vector that directly violates fundamental principles of secure communication protocols and certificate-based authentication.
The technical root cause of this vulnerability lies in the improper implementation of X.509 certificate validation logic within the SChannel integration layer. When establishing secure connections, the vulnerable library fails to perform proper hostname verification against the certificate's subject alternative name fields or the common name field in the certificate's subject. This validation process is crucial for preventing man-in-the-middle attacks, as it ensures that the certificate presented by the server actually corresponds to the expected hostname. The flaw specifically affects how the library processes the certificate chain and performs the comparison between the expected server name and the names contained within the certificate, allowing attackers to present any valid certificate that happens to be signed by a trusted authority without triggering the necessary security checks.
The operational impact of this vulnerability is severe and directly enables sophisticated man-in-the-middle attacks against systems using the affected Proton library. Attackers can intercept communications between clients and servers by presenting a valid certificate that matches the expected domain name but is actually controlled by the attacker. This allows them to decrypt and potentially modify communications without detection, effectively breaking the confidentiality and integrity guarantees that SSL/TLS protocols are designed to provide. The vulnerability affects any application that relies on the affected Proton library for secure messaging, particularly in enterprise environments where message brokers and distributed systems depend on secure communication channels. The attack surface is particularly concerning in scenarios involving financial services, healthcare systems, or any environment where secure data transmission is critical.
This vulnerability maps directly to CWE-295, which specifically addresses "Improper Certificate Validation," and aligns with ATT&CK technique T1552.001 for "Unsecured Credentials" and T1041 for "Exfiltration Over C2 Channel." The flaw represents a classic case of insufficient certificate validation that violates security best practices established by industry standards such as RFC 2818 and RFC 6125. Organizations using affected versions of Apache Qpid Proton should immediately implement mitigation strategies including upgrading to version 0.13.1 or later, which contains the necessary certificate validation fixes. Additional mitigations include implementing additional network-level security controls such as firewall rules, network segmentation, and monitoring for unusual certificate usage patterns. The vulnerability also highlights the importance of proper security testing and validation of cryptographic implementations, particularly when integrating with platform-specific security APIs like SChannel. Organizations should conduct thorough security assessments of their messaging infrastructure and ensure that all components are updated to versions that properly implement certificate validation according to established security standards and best practices.