CVE-2015-5824 in Watch
Summary
by MITRE
The NSURL implementation in the CFNetwork SSL component in Apple iOS before 9 does not properly verify X.509 certificates from SSL servers after a certificate change, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/21/2024
The vulnerability described in CVE-2015-5824 represents a critical flaw in Apple iOS's secure communication stack that persisted across versions prior to iOS 9. This issue resides within the CFNetwork SSL component's NSURL implementation, which forms the foundation for secure network communications in iOS applications. The vulnerability specifically targets the certificate verification process during SSL handshakes, creating a window where malicious actors can exploit the system's failure to properly validate X.509 certificates. The flaw becomes particularly dangerous when certificate changes occur during an active SSL session, as the system fails to revalidate the authenticity of the new certificate presented by the server.
The technical nature of this vulnerability stems from insufficient certificate validation logic that fails to properly authenticate X.509 certificates when they undergo changes during an established SSL connection. This represents a direct violation of standard security protocols where certificate verification should occur consistently throughout the entire communication lifecycle. The flaw allows attackers to perform man-in-the-middle attacks by presenting crafted certificates that appear legitimate to the iOS system, thereby bypassing the normal certificate validation mechanisms. This vulnerability directly maps to CWE-295, which addresses improper certificate validation, and aligns with ATT&CK technique T1573.002 for "Encrypted Channel" by enabling attackers to establish fraudulent secure connections.
The operational impact of CVE-2015-5824 is severe and far-reaching across iOS devices running vulnerable versions. Applications that rely on secure communications, including banking apps, email clients, and corporate communication tools, become vulnerable to interception and data theft. Attackers can exploit this vulnerability to eavesdrop on sensitive communications, steal session tokens, intercept login credentials, and access confidential information transmitted over supposedly secure connections. The vulnerability affects not only individual users but also enterprise environments where iOS devices handle sensitive corporate data, potentially leading to significant financial and reputational damage. Organizations with mobile device management policies may find their security postures weakened as this vulnerability exists in the core operating system rather than in specific applications.
Mitigation strategies for CVE-2015-5824 primarily focus on immediate system updates and enhanced security monitoring. The most effective solution involves upgrading to iOS 9 or later versions where Apple has implemented proper certificate validation mechanisms. System administrators should conduct comprehensive vulnerability assessments to identify devices running vulnerable iOS versions and prioritize their upgrade schedules. Network monitoring solutions should be enhanced to detect anomalous SSL traffic patterns that might indicate exploitation attempts. Additionally, organizations should implement certificate pinning techniques in their applications as an additional layer of defense, though this approach has limitations and requires careful implementation to avoid disrupting legitimate communications. The vulnerability highlights the importance of maintaining current operating system versions and demonstrates how fundamental security components can introduce systemic risks when not properly validated.