CVE-2012-6153 in Commons-httpclient
Summary
by MITRE
http/conn/ssl/AbstractVerifier.java in Apache Commons HttpClient before 4.2.3 does 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, which allows man-in-the-middle attackers to spoof SSL servers via a certificate with a subject that specifies a common name in a field that is not the CN field. NOTE: this issue exists because of an incomplete fix for CVE-2012-5783.
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Analysis
by VulDB Data Team • 06/20/2018
The vulnerability described in CVE-2012-6153 represents a critical security flaw in Apache Commons HttpClient library versions prior to 4.2.3, specifically within the ssl/conn/AbstractVerifier.java component. This issue fundamentally undermines the SSL/TLS certificate validation process that is essential for establishing secure communications between clients and servers. The vulnerability stems from an incomplete implementation of hostname verification mechanisms that should ensure the server certificate presented during SSL handshakes matches the domain name being accessed by the client.
The technical flaw manifests in the improper handling of X.509 certificate validation where the system fails to properly validate that the server hostname matches the domain name contained within the certificate's subject field. This occurs specifically when the certificate contains a common name in a field other than the traditional Common Name (CN) field, which is a valid certificate structure according to X.509 standards. The vulnerability exploits the fact that the verification process does not adequately check all relevant fields in the certificate's subject section, allowing malicious actors to craft certificates that appear valid to the client while actually pointing to a different server. This represents a classic man-in-the-middle attack vector that bypasses fundamental security controls designed to prevent such impersonation attacks.
The operational impact of this vulnerability is severe and far-reaching across any system utilizing Apache Commons HttpClient library versions before 4.2.3 for SSL/TLS communications. Attackers can successfully impersonate legitimate servers by presenting certificates that contain the target domain name in non-CN fields while leaving the CN field empty or containing irrelevant information. This allows them to intercept and potentially modify communications without detection, compromising sensitive data transmission, authentication processes, and overall system integrity. The vulnerability is particularly dangerous in environments where SSL/TLS is used for protecting web services, database connections, and other critical communication channels.
The root cause of this vulnerability can be traced to an incomplete fix for CVE-2012-5783, indicating that the previous remediation efforts were insufficient to address all possible certificate validation scenarios. This demonstrates the complexity of implementing proper SSL/TLS certificate verification mechanisms and the potential for subtle flaws in cryptographic library implementations. The issue aligns with CWE-295, which specifically addresses improper certificate validation, and relates to ATT&CK technique T1573.002 for secure communication channel protocols. Organizations that failed to update their Apache Commons HttpClient implementations remained exposed to attacks that could compromise their entire SSL/TLS infrastructure, making this vulnerability particularly concerning for enterprise environments with extensive use of this library.
The recommended mitigations for CVE-2012-6153 include immediate upgrade to Apache Commons HttpClient version 4.2.3 or later, which contains the complete fix for the hostname verification implementation. Additionally, organizations should implement comprehensive monitoring to detect any suspicious certificate validation behaviors and consider deploying additional security controls such as certificate pinning for critical applications. System administrators should also verify that all applications using the affected library have been properly updated and tested to ensure compatibility with the newer version. The vulnerability highlights the importance of thorough security testing and validation of cryptographic implementations, particularly those handling SSL/TLS certificate validation processes that are fundamental to secure communications.