CVE-2019-8668 in watchOS
Summary
by MITRE • 10/28/2020
A denial of service issue was addressed with improved validation. This issue is fixed in iOS 12.4, tvOS 12.4, watchOS 5.3. Processing a maliciously crafted image may lead to a denial of service.
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Analysis
by VulDB Data Team • 11/28/2020
The vulnerability identified as CVE-2019-8668 represents a critical denial of service flaw within Apple's mobile operating systems that was addressed through enhanced input validation mechanisms. This issue specifically affects iOS 12.4, tvOS 12.4, and watchOS 5.3, indicating that the flaw existed in Apple's image processing pipelines across multiple device platforms. The vulnerability arises from insufficient validation of image file formats when the operating system attempts to render or process maliciously crafted image data, creating a potential attack surface that could be exploited by adversaries to disrupt normal system operations.
The technical nature of this vulnerability aligns with CWE-20, which describes improper input validation as a fundamental weakness in software security. When a system fails to properly validate input data, it becomes susceptible to various forms of exploitation including denial of service attacks that can cause applications or entire operating system components to crash or become unresponsive. In this case, the flaw manifests specifically during image processing operations where the system encounters malformed or specially crafted image files that trigger unexpected behavior in the graphics rendering subsystem. The vulnerability demonstrates how seemingly benign file processing operations can become attack vectors when proper validation mechanisms are absent or insufficient.
The operational impact of CVE-2019-8668 extends beyond simple service disruption to potentially affect user productivity and device reliability across Apple's ecosystem. When exploited, this vulnerability could cause applications to crash or the entire operating system to become unresponsive, effectively rendering devices unusable until a reboot occurs. This type of denial of service attack represents a significant concern for users who depend on their mobile devices for critical communications and business operations, particularly in enterprise environments where device availability is paramount. The vulnerability affects not only individual users but also organizations that rely on Apple's mobile platforms for their operational infrastructure.
From a threat modeling perspective, this vulnerability maps to several ATT&CK techniques including T1499 which covers network denial of service attacks, and T1566 which addresses spearphishing with malicious attachments. Attackers could potentially deliver malicious image files through various vectors including email attachments, malicious websites, or social media platforms, targeting users who might inadvertently open these files on vulnerable devices. The remediation approach for this vulnerability focuses on implementing stricter input validation mechanisms that can detect and reject malformed image files before they reach the core processing components. This aligns with security best practices outlined in the OWASP Top Ten and other industry standards that emphasize the importance of defensive programming and input sanitization as primary defenses against injection and processing-based vulnerabilities. Organizations should prioritize updating affected systems to the patched versions of iOS 12.4, tvOS 12.4, and watchOS 5.3 to mitigate this risk effectively.