CVE-2016-4667 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.12.1 is affected. The issue involves the "ATS" 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 • 09/28/2022
The vulnerability identified as CVE-2016-4667 represents a critical security flaw within Apple's operating system ecosystem, specifically affecting macOS versions prior to 10.12.1. This issue resides within the Apple Type Services (ATS) component, which serves as the core font handling system responsible for processing and rendering various font formats across the macOS platform. The ATS component plays a fundamental role in the operating system's graphic rendering pipeline, making it a prime target for exploitation due to its widespread usage and deep integration with core system functions. The vulnerability manifests when the system processes specially crafted malicious font files, creating a dangerous attack vector that can be leveraged by remote threat actors to compromise system integrity.
The technical nature of this flaw stems from improper memory handling within the ATS font processing routines, specifically when parsing font files that contain malformed or maliciously constructed data structures. This memory corruption vulnerability falls under the category of heap-based buffer overflows or use-after-free conditions, where the system fails to properly validate font metadata and glyph information before processing. The vulnerability is particularly concerning because it operates at a low system level within the font rendering stack, allowing attackers to manipulate memory structures that control how fonts are displayed and processed. When a vulnerable system encounters a crafted font file, the improper validation leads to memory corruption that can result in arbitrary code execution or system crashes, effectively providing attackers with either complete system compromise or denial of service capabilities.
The operational impact of CVE-2016-4667 extends beyond simple system instability, presenting significant risks to enterprise environments and individual users alike. Attackers can leverage this vulnerability through various delivery mechanisms including email attachments, malicious websites, or compromised software installations that contain the malicious font files. The remote exploitation capability means that users do not need to perform any specific actions beyond viewing or interacting with the malicious font content, making it particularly dangerous in phishing campaigns or social engineering attacks. Organizations using affected macOS versions face potential data breaches, system compromise, and service disruption, as the vulnerability can be exploited to gain unauthorized access to sensitive information or to establish persistent footholds within network environments. The memory corruption aspect also makes this vulnerability difficult to detect through traditional security monitoring, as the system behavior may appear normal until the memory corruption triggers a crash or allows code execution.
The mitigation strategy for this vulnerability primarily involves updating to macOS 10.12.1 or later versions where Apple has implemented proper input validation and memory management fixes within the ATS component. System administrators should prioritize patch management and ensure all macOS devices are updated to the latest secure versions. Additionally, organizations should implement network-level controls such as web content filtering and email scanning to prevent the delivery of malicious font files. Security teams should monitor for indicators of compromise related to this vulnerability, including unusual system crashes or memory corruption patterns. From a cybersecurity framework perspective, this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write conditions, both of which are common in font processing and memory management contexts. The attack pattern follows ATT&CK technique T1203, which involves exploiting software vulnerabilities for privilege escalation and system compromise, demonstrating how seemingly benign font processing can become a critical attack surface in modern computing environments.