CVE-2014-2234 in Mac OS X
Summary
by MITRE
A certain Apple patch for OpenSSL in Apple OS X 10.9.2 and earlier uses a Trust Evaluation Agent (TEA) feature without terminating certain TLS/SSL handshakes as specified in the SSL_CTX_set_verify callback function s documentation, which allows remote attackers to bypass extra verification within a custom application via a crafted certificate chain that is acceptable to TEA but not acceptable to that application.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/24/2017
The vulnerability described in CVE-2014-2234 represents a critical security flaw in Apple's implementation of OpenSSL within OS X versions 10.9.2 and earlier. This issue stems from the improper handling of TLS/SSL certificate verification processes, specifically when the Trust Evaluation Agent (TEA) feature is employed alongside custom SSL_CTX_set_verify callback functions. The fundamental problem lies in the inconsistency between the certificate validation performed by Apple's TEA system and the additional verification requirements imposed by individual applications. When a certificate chain passes TEA's validation but fails the application's custom verification checks, the system fails to properly terminate the TLS/SSL handshake, creating a security bypass opportunity for malicious actors.
The technical flaw manifests in the OpenSSL implementation where Apple's OS X operating system does not properly enforce the SSL_CTX_set_verify callback function's documented behavior. According to standard SSL/TLS protocols and security best practices, when a custom verification callback is established through SSL_CTX_set_verify, the system should terminate the handshake if the callback function determines that the certificate chain is unacceptable. However, Apple's implementation allows the connection to proceed even when TEA validation passes but application-specific validation fails, effectively undermining the security controls that developers have implemented. This creates a scenario where an attacker can craft a certificate chain that meets Apple's default trust requirements but violates the specific security policies of individual applications, thereby bypassing critical security controls.
The operational impact of this vulnerability extends beyond simple certificate validation failures, representing a significant threat to secure communications in environments where custom SSL/TLS verification is implemented. Attackers can exploit this weakness to establish secure connections with applications that have implemented strict certificate validation policies, potentially allowing them to impersonate trusted entities or bypass authentication mechanisms. The vulnerability is particularly concerning in enterprise environments where applications rely on custom certificate verification to ensure proper security posture, as it essentially provides a backdoor that allows malicious certificates to be accepted even when they would normally be rejected by application-specific security policies. This weakness affects the core trust model of TLS/SSL implementations and can compromise the integrity of secure communications across multiple applications.
Organizations affected by this vulnerability should implement immediate mitigations including updating to Apple OS X 10.9.3 or later versions where the issue has been addressed, or applying the relevant security patches provided by Apple. Additionally, system administrators should review their certificate validation policies to ensure that applications are not relying solely on default trust evaluation mechanisms, and should consider implementing additional verification layers. The vulnerability aligns with CWE-284, which describes improper access control, and maps to ATT&CK technique T1071.004 for application layer protocol, specifically targeting the TLS/SSL communication protocols. Security teams should also consider monitoring for unusual certificate validation patterns and implement more robust certificate pinning mechanisms to mitigate potential exploitation of this vulnerability across their networks.