CVE-2016-7636 in watchOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 10.2 is affected. macOS before 10.12.2 is affected. watchOS before 3.1.3 is affected. The issue involves the "Security" component, which allows man-in-the-middle attackers to cause a denial of service (application crash) via vectors related to OCSP responder URLs.
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Analysis
by VulDB Data Team • 09/23/2024
This vulnerability resides within Apple's security infrastructure and affects multiple operating systems including iOS, macOS, and watchOS. The flaw specifically targets the Online Certificate Status Protocol implementation within these platforms, creating a potential pathway for malicious actors to disrupt normal application functionality. The vulnerability stems from insufficient validation of OCSP responder URLs which are critical components in certificate verification processes. Attackers can exploit this weakness by crafting malicious OCSP responder URLs that trigger application crashes when processed by affected systems. This represents a significant concern for enterprise environments where certificate validation plays a crucial role in maintaining secure communications and network integrity.
The technical nature of this vulnerability aligns with CWE-20, which describes improper input validation, and specifically relates to weaknesses in certificate validation mechanisms. The flaw allows attackers to manipulate the certificate status checking process by providing specially crafted OCSP responder URLs that cause applications to crash or become unresponsive. This occurs because the affected systems fail to properly sanitize or validate the URLs before attempting to establish connections with the specified responders. The implementation does not adequately handle malformed or malicious URLs, leading to memory corruption or resource exhaustion that results in application termination. This type of vulnerability falls under the ATT&CK technique T1557.001 for "Adversary-in-the-Middle" and T1499.004 for "Network Denial of Service" within the enterprise security framework.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the overall security posture of affected systems. When applications crash due to malformed OCSP responder URLs, it can create denial of service conditions that prevent legitimate users from accessing services or applications that rely on certificate validation. This becomes particularly problematic in enterprise environments where certificate validation is critical for secure web browsing, email communications, and internal network services. The vulnerability affects systems running iOS before 10.2, macOS before 10.12.2, and watchOS before 3.1.3, representing a substantial user base that requires immediate remediation. Organizations using these affected versions face increased risk of service interruptions and potential exploitation for more sophisticated attacks that could leverage the initial denial of service as a stepping stone for further compromise.
Mitigation strategies for this vulnerability primarily focus on applying the relevant security updates provided by Apple. The recommended approach involves upgrading to iOS 10.2, macOS 10.12.2, or watchOS 3.1.3, which contain patches addressing the OCSP responder URL validation issue. Network administrators should also implement monitoring solutions to detect unusual certificate validation activity or potential exploitation attempts. Additional protective measures include configuring firewalls to restrict access to potentially malicious OCSP responder endpoints and implementing certificate pinning where appropriate to reduce reliance on dynamic OCSP validation. Organizations should conduct thorough testing of updates in controlled environments before deployment to ensure compatibility with existing applications and services. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and highlights the need for robust input validation mechanisms in security-critical components of operating systems and applications.