CVE-2012-5662 in x3270
Summary
by MITRE
x3270 before 3.3.12ga12 does not 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 an arbitrary valid certificate.
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Analysis
by VulDB Data Team • 03/10/2019
The vulnerability identified as CVE-2012-5662 affects the x3270 terminal emulator version 3.3.12ga12 and earlier, presenting a critical security flaw in the SSL/TLS certificate validation process. This issue resides in the certificate verification mechanism that fails to properly validate the hostname against the X.509 certificate's subject common name or subject alternative name fields, creating a significant security gap that can be exploited by malicious actors. The vulnerability specifically targets the SSL/TLS hostname validation process, which is a fundamental security control designed to prevent man-in-the-middle attacks by ensuring that the server presenting the certificate is indeed the legitimate entity it claims to be.
The technical flaw manifests in the improper implementation of certificate hostname validation within the x3270 application, which operates under the CWE-295 weakness category related to improper certificate validation. This weakness allows attackers to perform successful man-in-the-middle attacks by presenting any valid SSL certificate, regardless of whether it matches the target server's hostname. The vulnerability occurs because the application does not perform the standard hostname verification procedure that checks if the certificate's subject common name or subject alternative name fields contain a domain name that matches the server being connected to. This omission leaves the application susceptible to attacks where an attacker can intercept communications and present a valid certificate for a different domain, fooling the client into trusting the fraudulent connection.
The operational impact of this vulnerability is severe, as it fundamentally undermines the security of SSL/TLS communications within the x3270 terminal emulator. Organizations using affected versions of x3270 may experience unauthorized access to sensitive data, as attackers can intercept and potentially modify communications between clients and servers. This vulnerability is particularly dangerous in enterprise environments where mainframe connections are common, as it can lead to the compromise of critical business data and systems. The attack vector requires minimal sophistication, as attackers only need to possess a valid SSL certificate and can exploit the trust relationship established by the vulnerable application to gain access to network resources. This vulnerability directly aligns with ATT&CK technique T1046 which involves network service scanning, and T1566 which involves credential harvesting through social engineering, as the compromised system can be used to capture credentials and sensitive information.
The mitigation strategy for CVE-2012-5662 involves upgrading to x3270 version 3.3.12ga12 or later, which implements proper certificate hostname validation. Organizations should also consider implementing additional security controls such as certificate pinning, where specific certificate fingerprints are hardcoded into applications to prevent the acceptance of unauthorized certificates. Network administrators should monitor for unusual certificate usage patterns and implement certificate monitoring solutions to detect potential attacks. The fix addresses the core issue by implementing proper hostname verification against the certificate's subject alternative name and common name fields, ensuring that the server certificate matches the expected domain name. This remediation aligns with industry best practices outlined in NIST SP 800-57 and RFC 6125, which specify the requirements for proper certificate validation and hostname verification in secure communications. Organizations should also review their certificate management policies and ensure that all applications performing SSL/TLS connections implement proper certificate validation mechanisms to prevent similar vulnerabilities from occurring in other systems.