CVE-2016-4631 in tvOS
Summary
by MITRE
ImageIO in Apple iOS before 9.3.3, OS X before 10.11.6, tvOS before 9.2.2, and watchOS before 2.2.2 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted TIFF file.
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Analysis
by VulDB Data Team • 09/06/2022
The vulnerability identified as CVE-2016-4631 represents a critical memory corruption flaw within Apple's ImageIO framework that affects multiple operating systems including iOS, macOS, tvOS, and watchOS. This vulnerability stems from insufficient input validation when processing TIFF image files, creating a pathway for remote attackers to exploit memory handling mechanisms through maliciously crafted image content. The flaw exists in the ImageIO component responsible for processing various image formats including TIFF, which is widely used across Apple platforms for image display and manipulation tasks. The vulnerability is particularly concerning because it can be triggered through various attack vectors including email attachments, web content, and file downloads, making it highly exploitable in real-world scenarios. The memory corruption occurs during the parsing and rendering process of TIFF files, where the ImageIO framework fails to properly validate the structure and content of image metadata, leading to potential buffer overflows or other memory management errors that could be leveraged for code execution.
The technical implementation of this vulnerability involves the improper handling of TIFF file structures where the ImageIO framework does not adequately validate the size parameters and metadata fields within the image file format. When processing a specially crafted TIFF file, the framework attempts to allocate memory based on malformed size values or excessive metadata entries, resulting in memory corruption that can be exploited to execute arbitrary code with the privileges of the affected application. This type of vulnerability is classified as a memory safety issue and aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient validation of buffer sizes leads to memory corruption. The vulnerability demonstrates characteristics of a remote code execution flaw that can be triggered without user interaction, as the exploitation can occur during automatic image processing by applications or system components that automatically parse image files. The attack surface is extensive since TIFF files are commonly encountered in email attachments, web browsing, and file sharing scenarios, making the vulnerability particularly dangerous for widespread exploitation.
The operational impact of CVE-2016-4631 extends beyond simple denial of service conditions to encompass full system compromise potential through remote code execution capabilities. Attackers can leverage this vulnerability to gain unauthorized access to affected systems, potentially leading to data theft, system takeover, or deployment of additional malicious software. The vulnerability affects a broad range of Apple devices including iPhones, iPads, Mac computers, Apple TV sets, and Apple Watch devices, creating a significant security risk across the entire Apple ecosystem. The memory corruption can manifest in various ways including application crashes, system instability, or complete system compromise depending on the exploitation method and target system configuration. Organizations and users face substantial risk as this vulnerability can be exploited through automated attacks without requiring user interaction, making it particularly dangerous for enterprise environments where Apple devices are prevalent. The vulnerability also impacts the broader security posture of Apple's platform, as it demonstrates weaknesses in the image processing pipeline that could be indicative of broader memory safety issues within the operating system framework.
Mitigation strategies for CVE-2016-4631 primarily focus on immediate system updates and patch management to address the underlying memory handling flaws in Apple's ImageIO framework. Apple released security updates for all affected operating systems including iOS 9.3.3, macOS 10.11.6, tvOS 9.2.2, and watchOS 2.2.2, which contain fixes for the memory corruption issues in TIFF file processing. System administrators should prioritize deployment of these security patches across all affected devices to eliminate the exploitation risk. Additional protective measures include implementing email filtering and web content security controls that can prevent automatic processing of TIFF files from untrusted sources, along with network-level filtering to block suspicious image file transfers. The vulnerability also highlights the importance of input validation and memory safety practices in image processing libraries, aligning with ATT&CK technique T1059.007 for command and scripting interpreter usage in exploitation scenarios. Organizations should also consider implementing sandboxing mechanisms for image processing applications and monitoring for unusual memory allocation patterns that could indicate exploitation attempts. Regular security assessments of image processing components and adherence to secure coding practices for buffer management and input validation are essential long-term strategies to prevent similar vulnerabilities from emerging in the future.