CVE-2011-5238 in checkout-php
Summary
by MITRE
google-checkout-php-sample-code before 1.3.2 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 • 02/23/2019
The vulnerability described in CVE-2011-5238 affects the google-checkout-php-sample-code library version 1.3.1 and earlier, representing a critical SSL/TLS security flaw that undermines the integrity of secure communications. This issue stems from improper certificate validation mechanisms within the PHP implementation, creating a pathway for attackers to execute successful man-in-the-middle attacks against systems utilizing this codebase. The vulnerability specifically targets the SSL certificate verification process, where the system fails to properly validate that the server hostname matches the domain name present in either the Common Name field or subjectAltName field of the X.509 certificate. This flaw directly violates fundamental security principles of SSL/TLS protocol implementation and creates a significant risk for any system relying on this vulnerable code for payment processing or secure communications.
The technical nature of this vulnerability places it squarely within the scope of CWE-295, which addresses "Improper Certificate Validation" in security protocols. This weakness allows attackers to bypass hostname validation checks that are essential for preventing certificate forgery attacks. The implementation flaw specifically manifests when the PHP library performs SSL connections without properly verifying that the certificate presented by the server corresponds to the expected hostname. This failure creates a condition where any valid SSL certificate, regardless of its intended domain, can be accepted as legitimate, enabling attackers to intercept and manipulate communications between clients and servers. The vulnerability operates at the application layer, affecting the secure socket layer implementation within the PHP environment and represents a classic example of insufficient cryptographic validation that has been documented in numerous security advisories.
From an operational impact perspective, this vulnerability poses severe risks to e-commerce systems and payment processing environments that rely on the affected google-checkout-php-sample-code. Attackers can exploit this weakness to intercept sensitive payment information, customer data, and transaction details during SSL communications. The vulnerability's exploitation potential aligns with techniques described in the MITRE ATT&CK framework under the T1573.001 technique for "Tunneling through Secure Shell (SSH)" and T1041 for "Exfiltration Over C2 Channel," though the specific attack vector here is more directly related to man-in-the-middle protocol manipulation. Organizations using this vulnerable code may experience data breaches, financial losses, and regulatory compliance violations, particularly in environments subject to pci dss requirements where secure payment processing is mandatory. The impact extends beyond immediate financial harm to include reputational damage and potential legal consequences from failing to maintain proper security controls.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security hardening measures. The primary solution involves upgrading to google-checkout-php-sample-code version 1.3.2 or later, which includes proper hostname validation for SSL certificates. Organizations should implement comprehensive certificate management policies that enforce strict validation of certificate subject names and implement automated monitoring for vulnerable systems. Additional defensive measures include enabling strict SSL certificate verification flags, implementing certificate pinning where appropriate, and conducting regular security assessments of all third-party libraries and code components. The remediation process should also include network-level monitoring to detect potential exploitation attempts and implementation of intrusion detection systems that can identify man-in-the-middle attack patterns. Security teams must ensure that all systems using this library undergo thorough vulnerability scanning and that proper certificate validation is enforced at the application level, as this vulnerability represents a fundamental failure in the security architecture that could expose sensitive data to unauthorized access.