CVE-2013-4366 in HttpClient
Summary
by MITRE
http/impl/client/HttpClientBuilder.java in Apache HttpClient 4.3.x before 4.3.1 does not ensure that X509HostnameVerifier is not null, which allows attackers to have unspecified impact via vectors involving hostname verification.
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Analysis
by VulDB Data Team • 12/02/2019
The vulnerability identified as CVE-2013-4366 affects Apache HttpClient version 4.3.x prior to 4.3.1, specifically within the http/impl/client/HttpClientBuilder.java component. This flaw represents a critical security oversight that undermines the certificate validation process during secure communications. The vulnerability stems from the HttpClientBuilder implementation failing to properly validate the presence of X509HostnameVerifier instances, creating a potential security gap that could be exploited by malicious actors.
The technical flaw manifests when the X509HostnameVerifier parameter is not explicitly set or validated during the HttpClient configuration process. In normal operation, this verifier should ensure that the hostname specified in the SSL/TLS certificate matches the actual host being connected to, preventing man-in-the-middle attacks. However, when the verifier is null or improperly handled, the system may proceed with connections without proper hostname verification, potentially accepting certificates for incorrect hosts. This issue falls under CWE-295 which specifically addresses improper certificate validation and hostname verification failures in security implementations.
The operational impact of this vulnerability is significant as it allows attackers to exploit the missing hostname verification mechanism to perform various malicious activities. An attacker could potentially intercept communications by presenting a valid certificate for a different host, or manipulate connections to redirect traffic to malicious endpoints. The unspecified impact mentioned in the CVE description suggests that the consequences could range from data interception to complete system compromise depending on the specific attack vector and target environment. This vulnerability directly aligns with ATT&CK technique T1046 which covers network service scanning and T1566 which covers credential harvesting through social engineering, as it creates opportunities for attackers to establish unauthorized connections.
Organizations using affected Apache HttpClient versions should immediately upgrade to 4.3.1 or later to address this vulnerability. The mitigation strategy involves ensuring that all HttpClient configurations explicitly set a valid X509HostnameVerifier implementation, typically using the default hostname verifier provided by the library. Security teams should also conduct comprehensive audits of all applications using Apache HttpClient to verify proper certificate validation implementation. Additionally, network monitoring should be enhanced to detect unusual connection patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and security parameter handling in cryptographic libraries, emphasizing that even seemingly minor configuration oversight can create substantial security risks in enterprise environments.