CVE-2016-7595 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 "CoreText" component. It allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted font.
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Analysis
by VulDB Data Team • 09/19/2024
The vulnerability identified as CVE-2016-7595 represents a critical memory corruption flaw within Apple's CoreText framework that affects multiple operating systems including iOS, macOS, and watchOS. This vulnerability stems from insufficient input validation within the font processing pipeline, specifically when handling crafted font files that contain malformed or maliciously constructed data structures. The CoreText component serves as a fundamental text rendering engine responsible for processing and displaying text across Apple's ecosystem, making it a prime target for attackers seeking to exploit system-level weaknesses. The flaw manifests when the system attempts to parse specially crafted font files that contain unexpected data patterns, leading to unpredictable memory behavior that can be leveraged for remote code execution or denial of service attacks.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read errors. These classifications reflect the fundamental memory corruption characteristics present in the CoreText implementation where attacker-controlled data can overwrite adjacent memory locations or trigger invalid memory access patterns. The attack vector requires remote delivery of malicious font files through various channels including email attachments, web downloads, or malicious websites that automatically trigger font rendering when viewed. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1059.007, which involves the use of scripting languages, as the exploitation can occur through automated font processing mechanisms within the operating system's text rendering stack.
The operational impact of this vulnerability extends across Apple's entire product portfolio, affecting iOS versions prior to 10.2, macOS versions before 10.12.2, and watchOS versions before 3.1.3, creating a significant attack surface that could compromise user devices without requiring any user interaction beyond viewing content that triggers font rendering. Attackers can exploit this vulnerability to execute arbitrary code with the privileges of the affected application, potentially leading to full system compromise, or cause application crashes that result in denial of service conditions. The memory corruption aspect of the flaw makes it particularly dangerous as it can lead to unpredictable system behavior, including privilege escalation opportunities and persistent system instability that could be exploited for more sophisticated attacks. The vulnerability's remote nature means that users can be compromised simply by encountering malicious content that triggers the font processing path, making it an attractive target for widespread exploitation campaigns.
Mitigation strategies for CVE-2016-7595 primarily focus on applying the official security updates released by Apple, which include patches to the CoreText framework that implement proper input validation and memory bounds checking for font processing operations. System administrators should prioritize immediate deployment of the relevant security patches for iOS 10.2, macOS 10.12.2, and watchOS 3.1.3, as these updates address the underlying memory corruption issues. Organizations should also consider implementing network-level controls to block or scan font files from untrusted sources, particularly in enterprise environments where users may encounter malicious content. Additional protective measures include disabling automatic font rendering for web content where possible, implementing application sandboxing to limit potential damage from exploitation attempts, and monitoring for unusual application crashes or memory access patterns that could indicate exploitation attempts. The vulnerability highlights the importance of proper input validation in system-level components and demonstrates how seemingly benign functionality like text rendering can become a critical attack surface when proper security controls are not implemented.