CVE-2015-5942 in Mac OS X
Summary
by MITRE
FontParser in Apple iOS before 9.1, OS X before 10.11.1, and watchOS before 2.0.1 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted font file, a different vulnerability than CVE-2015-5927.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 11/19/2024
The vulnerability identified as CVE-2015-5942 represents a critical memory corruption flaw within Apple's FontParser component that affected multiple operating systems including iOS versions prior to 9.1, macOS versions before 10.11.1, and watchOS versions before 2.0.1. This vulnerability resides in the system's font handling mechanisms and demonstrates how seemingly benign file processing can become a vector for severe security compromises. The flaw specifically manifests when the system processes crafted font files, which can trigger unpredictable behavior leading to either arbitrary code execution or denial of service conditions. This issue operates under the broader category of software security vulnerabilities related to input validation and memory management, making it particularly dangerous as it can be exploited remotely without user interaction.
The technical implementation of this vulnerability stems from insufficient validation of font file structures within Apple's rendering pipeline. When a maliciously crafted font file is processed, the FontParser fails to properly validate the file's internal structure and memory allocation patterns, leading to memory corruption that can be leveraged by attackers. The vulnerability operates at the intersection of multiple attack vectors as defined by the ATT&CK framework, particularly under the T1059.007 technique for process injection and T1203 for legitimate program execution. This memory corruption typically occurs during font rendering operations where the system allocates memory based on malformed font data, creating opportunities for attackers to manipulate memory layout and execute malicious code. The flaw is classified as a buffer overflow or memory corruption vulnerability, which aligns with CWE-121 which addresses stack-based buffer overflow conditions.
The operational impact of CVE-2015-5942 extends beyond simple denial of service scenarios to encompass full system compromise capabilities. Attackers can exploit this vulnerability remotely through various delivery mechanisms including email attachments, web downloads, or malicious websites that serve crafted font files. The vulnerability affects all affected Apple platforms and demonstrates the inherent risks in processing untrusted binary data formats. Once exploited, the vulnerability can allow attackers to execute arbitrary code with the privileges of the affected application, potentially leading to complete system compromise. This makes the vulnerability particularly concerning as it can be leveraged in targeted attacks against iOS devices, macOS systems, and Apple Watch devices, all of which are commonly used in enterprise and personal environments where sensitive data is stored.
Mitigation strategies for CVE-2015-5942 primarily focus on immediate system updates and patches provided by Apple. Organizations should prioritize deployment of the relevant security updates for iOS 9.1, macOS 10.11.1, and watchOS 2.0.1 to address the vulnerability. Additional defensive measures include implementing network-based filtering to block suspicious font file types, deploying application whitelisting policies, and monitoring for unusual font processing activities. Security teams should also consider implementing sandboxing mechanisms around font processing components and establishing network segmentation to limit the potential impact of successful exploitation. The vulnerability highlights the importance of robust input validation and memory safety practices in system design, emphasizing the need for regular security assessments of core system components. Organizations should also implement comprehensive monitoring solutions to detect potential exploitation attempts and maintain detailed incident response procedures specifically addressing font-based vulnerabilities.