CVE-2016-4674 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 local users to gain privileges or cause a denial of service (memory corruption and application crash) via unspecified vectors.
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Analysis
by VulDB Data Team • 09/28/2022
The vulnerability identified as CVE-2016-4674 resides within Apple's macOS operating system, specifically affecting versions prior to 10.12.1. This issue manifests within the ATS component, which stands for Apple Type Services, a core system framework responsible for font handling and text rendering operations. The ATS component serves as a critical interface for managing font data and text processing across various macOS applications, making it a potential attack surface for privilege escalation or system instability. The vulnerability's classification as a local privilege escalation issue indicates that an attacker with existing user-level access could potentially leverage this flaw to execute code with elevated privileges, while simultaneously creating conditions that could result in denial of service through memory corruption.
The technical nature of this vulnerability stems from improper memory management within the ATS framework's handling of font-related data structures. When macOS processes font files or text rendering operations through ATS, specific input validation or memory allocation routines contain flaws that can be exploited through crafted font data or text inputs. These memory corruption vulnerabilities typically arise from buffer overflows, use-after-free conditions, or improper bounds checking within the font processing code paths. The unspecified vectors mentioned in the description suggest that multiple attack scenarios could trigger the underlying memory corruption, potentially including malformed font files, specially crafted text documents, or even legitimate font processing operations that inadvertently expose the vulnerability. This broad attack surface makes the flaw particularly concerning as it could be exploited through various legitimate system usage patterns.
The operational impact of CVE-2016-4674 extends beyond simple denial of service conditions to potentially enable full system compromise. Local users who can execute code on the affected system could leverage this vulnerability to escalate their privileges from standard user level to administrative access, thereby gaining complete control over the affected macOS system. The memory corruption aspect creates instability that could cause application crashes or system-wide failures, disrupting normal operations and potentially leading to data loss or system unavailability. From an attacker's perspective, this vulnerability represents a valuable tool for establishing persistent access to target systems, as the privilege escalation capability would allow for long-term system control and data exfiltration. The impact is particularly severe in enterprise environments where macOS systems may be used for sensitive operations and where local privilege escalation could provide access to critical infrastructure components.
Mitigation strategies for CVE-2016-4674 primarily focus on immediate system updates and operational security measures. Apple addressed this vulnerability through the release of macOS 10.12.1, which included patches to the ATS framework that corrected the memory handling issues. Organizations should prioritize deploying these security updates across all affected macOS systems to eliminate the vulnerability exposure. Additionally, implementing application whitelisting policies and restricting font processing capabilities in critical applications can provide additional layers of defense. System administrators should monitor for any unusual application crashes or memory usage patterns that might indicate exploitation attempts, while also maintaining regular security audits of font handling processes. The vulnerability's nature aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write vulnerabilities, both of which are common in font processing and text rendering components. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and defense evasion methods, as exploitation could enable attackers to maintain persistent access while potentially evading detection through legitimate system processes.