CVE-2015-3996 in AFNetworking
Summary
by MITRE
The default AFSecurityPolicy.validatesDomainName configuration for AFSSLPinningModeNone in the AFNetworking framework before 2.5.3, as used in the ownCloud iOS Library, disables verification of a server hostname against the domain name in the subject's Common Name (CN) of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 06/25/2022
The vulnerability described in CVE-2015-3996 represents a critical security flaw in the AFNetworking iOS framework that affected versions prior to 2.5.3. This issue specifically impacts the SSL certificate validation mechanism within the ownCloud iOS Library, creating a significant pathway for attackers to conduct man-in-the-middle attacks. The flaw stems from the default configuration of AFSecurityPolicy that operates under the AFSSLPinningModeNone setting, which fundamentally undermines the cryptographic security assurances that SSL/TLS connections are designed to provide.
The technical implementation of this vulnerability resides in the improper handling of X.509 certificate validation processes within the AFNetworking framework. When AFSSLPinningModeNone is configured, the system fails to validate that the server hostname matches the domain name specified in the certificate's Common Name field, which is a fundamental requirement for establishing trust in SSL/TLS communications. This validation step is crucial because it prevents attackers from using valid certificates issued for different domains to impersonate legitimate servers. The absence of this verification creates a scenario where any valid certificate can be used to establish a seemingly legitimate connection, effectively bypassing the certificate authority validation process that forms the backbone of web security.
The operational impact of this vulnerability extends far beyond simple network communication issues, as it fundamentally compromises the integrity of SSL/TLS connections within affected applications. Attackers can exploit this weakness by obtaining any valid SSL certificate and using it to establish connections to servers that appear to be legitimate, making it extremely difficult for end users to detect malicious activity. This vulnerability directly aligns with CWE-295, which addresses improper certificate validation, and represents a significant deviation from the established security practices outlined in industry standards such as RFC 2818 and RFC 6125 that specify the requirements for hostname verification in SSL/TLS contexts. The implications are particularly severe for applications like ownCloud that handle sensitive user data, as this vulnerability could enable attackers to intercept, modify, or steal confidential information transmitted between users and servers.
The mitigation strategy for this vulnerability involves updating to AFNetworking version 2.5.3 or later, which implements proper SSL certificate validation by default. Organizations should also consider implementing additional security measures such as certificate pinning to provide defense-in-depth against potential certificate-based attacks. System administrators and security teams should conduct thorough vulnerability assessments to identify all applications using affected versions of AFNetworking and ensure proper certificate validation is enabled. The remediation process must include not only software updates but also security awareness training for developers to prevent similar issues in future implementations. This vulnerability serves as a critical reminder of the importance of proper cryptographic implementation and the potential consequences of inadequate security controls in mobile application development environments.