CVE-2012-5789 in Payments Standard
Summary
by MITRE
PayPal Payments Standard PHP Library before 20120427 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, related to intentional disabling of certificate-validation checks through a "FALSE" value.
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Analysis
by VulDB Data Team • 02/06/2018
The vulnerability identified as CVE-2012-5789 affects the PayPal Payments Standard PHP Library version prior to 20120427, representing a critical security flaw in SSL/TLS certificate validation mechanisms. This issue stems from the library's failure to properly validate SSL certificates by not verifying that the server hostname matches either the Common Name field or the Subject Alternative Name fields within the X.509 certificate structure. The vulnerability manifests when certificate validation checks are intentionally disabled through the use of a "FALSE" value, creating an environment where malicious actors can exploit the lack of proper hostname verification.
The technical flaw in this vulnerability resides in the library's implementation of SSL certificate validation routines, specifically bypassing the standard hostname verification process that should occur during SSL handshakes. According to the certificate validation standards, when establishing secure connections, the SSL/TLS implementation should verify that the hostname being connected to matches one of the domain names listed in the certificate's subject or subject alternative name fields. This validation is crucial for preventing man-in-the-middle attacks where attackers present valid certificates for different domains to intercept communications.
This vulnerability creates significant operational risks for systems using the affected PayPal library, as it allows attackers to perform successful man-in-the-middle attacks by presenting arbitrary valid certificates. The impact extends beyond simple data interception, potentially enabling attackers to capture sensitive payment information, user credentials, and other confidential data transmitted through the vulnerable connections. The flaw essentially undermines the fundamental security assurance that SSL/TLS certificates provide, making it possible for attackers to establish seemingly legitimate connections while actually routing traffic through their own systems.
The vulnerability aligns with CWE-295, which specifically addresses "Improper Certificate Validation," and relates to ATT&CK technique T1573.002 for "Encrypted Channel: Asymmetric Cryptography." Organizations using the affected library face increased risk of credential theft, payment fraud, and data breaches. The flaw demonstrates poor security implementation practices where developers intentionally disabled security checks for convenience or compatibility reasons, creating a dangerous trade-off between functionality and security. This type of vulnerability is particularly concerning in payment processing systems where the integrity of SSL connections is paramount for protecting sensitive financial data.
Mitigation strategies for this vulnerability include immediate upgrading to the patched version of the PayPal Payments Standard PHP Library released after April 27, 2012, which properly implements certificate validation. Organizations should also implement additional security measures such as certificate pinning, regular security audits of SSL implementations, and monitoring for unauthorized certificate changes. System administrators must ensure that SSL/TLS configurations enforce proper hostname verification and disable any functionality that allows certificate validation to be bypassed. The incident highlights the importance of maintaining secure coding practices and avoiding intentional disabling of security features, even when such actions may seem to provide short-term benefits.