CVE-2018-8039 in Communications Session Route Manager
Summary
by MITRE
It is possible to configure Apache CXF to use the com.sun.net.ssl implementation via 'System.setProperty("java.protocol.handler.pkgs", "com.sun.net.ssl.internal.www.protocol");'. When this system property is set, CXF uses some reflection to try to make the HostnameVerifier work with the old com.sun.net.ssl.HostnameVerifier interface. However, the default HostnameVerifier implementation in CXF does not implement the method in this interface, and an exception is thrown. However, in Apache CXF prior to 3.2.5 and 3.1.16 the exception is caught in the reflection code and not properly propagated. What this means is that if you are using the com.sun.net.ssl stack with CXF, an error with TLS hostname verification will not be thrown, leaving a CXF client subject to man-in-the-middle attacks.
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Analysis
by VulDB Data Team • 07/16/2024
The vulnerability described in CVE-2018-8039 resides within the Apache CXF web services framework, specifically in how it handles TLS hostname verification when configured to use legacy SSL implementations. This issue stems from the configuration option that allows developers to specify the system property java.protocol.handler.pkgs to point to com.sun.net.ssl.internal.www.protocol, which instructs the application to utilize the older Sun SSL implementation rather than the standard Java Secure Socket Extension. The vulnerability manifests when CXF attempts to perform hostname verification using reflection mechanisms designed to bridge compatibility between different SSL interfaces. When the default CXF HostnameVerifier implementation lacks the required method signature expected by the legacy com.sun.net.ssl.HostnameVerifier interface, an exception should normally be thrown to indicate the mismatch.
The technical flaw in this vulnerability lies in the improper exception handling within CXF's reflection code, which was present in versions prior to 3.2.5 and 3.1.16. The system catches the exception that would normally indicate a hostname verification failure and suppresses it rather than propagating it to the calling application. This design flaw creates a false sense of security where TLS hostname verification errors are silently ignored, allowing potentially malicious actors to perform man-in-the-middle attacks without the application detecting the compromised connection. The vulnerability directly maps to CWE-295 which addresses improper certificate validation and CWE-310 which covers cryptographic issues related to key management and validation. From an operational perspective, this vulnerability represents a critical security gap that undermines the fundamental purpose of TLS hostname verification, which is to ensure that clients are communicating with the intended server and not an attacker positioned in the network path.
The impact of this vulnerability extends beyond simple network security concerns into broader application integrity risks, as it allows attackers to bypass critical authentication mechanisms that are supposed to protect against impersonation attacks. The ATT&CK framework categorizes this issue under T1557 which covers "Adversary-in-the-Middle" techniques, where attackers can intercept and manipulate communications without detection. Organizations using affected versions of Apache CXF with legacy SSL configurations are particularly at risk, as the vulnerability remains undetected even when TLS connections appear to succeed. The suppressed exception means that applications continue to operate with potentially compromised connections, creating a false positive security state where the system believes it is properly validating server identities. Security teams should prioritize patching affected systems, as the vulnerability cannot be mitigated through configuration changes alone, and organizations must upgrade to versions 3.2.5 or 3.1.16 where the exception handling has been corrected to properly propagate hostname verification failures. The vulnerability underscores the importance of proper exception handling in cryptographic libraries and demonstrates how seemingly minor implementation details can create significant security holes that expose applications to active attack vectors.