CVE-2011-5236 in Eselect Plus
Summary
by MITRE
Moneris eSelectPlus 2.03 PHP API 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 • 02/04/2018
The vulnerability identified as CVE-2011-5236 resides within the Moneris eSelectPlus 2.03 PHP API implementation, representing a critical SSL/TLS security flaw that fundamentally undermines the integrity of secure communications. This weakness stems from inadequate certificate validation mechanisms within the application's SSL handshake process, specifically failing to perform proper hostname verification against the X.509 certificates presented by remote servers. The vulnerability manifests when the API accepts any valid SSL certificate without confirming that the certificate's subject domain matches the intended server hostname, creating a significant attack surface for malicious actors.
This flaw directly corresponds to CWE-295, which addresses "Improper Certificate Validation," and operates under the broader category of weak cryptographic implementations that enable man-in-the-middle attacks. The technical implementation fails to validate the certificate's subject alternative name fields or the common name field against the expected hostname, allowing attackers to intercept communications by presenting a valid certificate for a different domain. The vulnerability exists in the PHP SSL/TLS verification layer where the application relies on basic certificate acceptance rather than comprehensive hostname matching, which is a fundamental requirement for secure SSL communications according to industry standards including the TLS protocol specifications and RFC 2818.
The operational impact of this vulnerability extends beyond simple data interception, as it enables sophisticated attack scenarios where adversaries can establish false SSL endpoints that appear legitimate to the client application. Attackers can leverage this weakness to perform session hijacking, capture sensitive payment information, and potentially gain access to backend systems that rely on the Moneris API for transaction processing. The implications are particularly severe for financial applications where eSelectPlus is used for payment processing, as the vulnerability could lead to unauthorized transactions and complete compromise of payment card data. This vulnerability falls under the MITRE ATT&CK framework's technique T1573.002 for "Reversible Encryption," as it enables attackers to establish secure communication channels that appear legitimate while actually facilitating data exfiltration.
The attack vector for this vulnerability requires an attacker to position themselves within the network path between the client application and the Moneris server, typically through network interception techniques such as ARP spoofing, DNS poisoning, or network traffic manipulation. The attacker must present a valid SSL certificate that is trusted by the client system but does not match the expected hostname, which can be achieved through various methods including certificate authority compromise or creation of self-signed certificates that are manually trusted. Organizations using this vulnerable API face significant risk of payment card data breaches, as the vulnerability directly enables the theft of sensitive information during SSL communications. The lack of proper hostname verification creates a false sense of security where the application believes it is communicating with a legitimate server while actually interacting with an attacker-controlled endpoint.
Mitigation strategies for this vulnerability require immediate implementation of proper SSL certificate validation procedures within the PHP application layer. Organizations should upgrade to patched versions of the Moneris eSelectPlus API that implement comprehensive hostname verification against both the common name and subject alternative name fields of X.509 certificates. The solution must enforce strict matching between the expected server hostname and certificate attributes, ensuring that any certificate presented during the SSL handshake must contain the target domain in either the CN or SAN fields. Additionally, implementing certificate pinning mechanisms and regular security audits of SSL implementations can help prevent similar vulnerabilities from emerging in the future. The remediation approach should align with PCI DSS requirements and industry best practices for secure SSL implementation, ensuring that all certificate validation processes adhere to the standards established by the TLS protocol and security frameworks such as NIST SP 800-57.