CVE-2016-4634 in Mac OS X
Summary
by MITRE
The Graphics Drivers subsystem in Apple OS X before 10.11.6 allows local users to gain privileges or cause a denial of service (memory corruption) via unspecified vectors.
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Analysis
by VulDB Data Team • 09/06/2022
The vulnerability identified as CVE-2016-4634 resides within the Graphics Drivers subsystem of Apple's operating system, specifically affecting versions prior to 10.11.6. This issue represents a critical security flaw that demonstrates the inherent risks associated with graphics driver components in operating systems, particularly when they handle untrusted input from local users. The vulnerability's classification as a privilege escalation flaw indicates that attackers with local access could potentially elevate their system privileges, while the denial of service component suggests memory corruption that could disrupt normal system operations. Such vulnerabilities in graphics drivers are particularly concerning because these components often run with elevated privileges and maintain direct hardware access, creating a substantial attack surface that can be exploited to compromise system integrity and availability.
The technical nature of this vulnerability stems from unspecified vectors within the graphics drivers subsystem, which typically handles complex rendering operations and hardware abstraction tasks. Graphics drivers operate at a low level within the operating system, interfacing directly with GPU hardware and managing memory allocation for graphical operations. When memory corruption occurs in such components, it can result in unpredictable behavior that may manifest as privilege escalation opportunities or system crashes. The unspecified nature of the vectors suggests that multiple attack paths within the graphics driver implementation could lead to the same underlying memory corruption issue, making the vulnerability particularly challenging to fully understand and remediate. This type of flaw often originates from improper input validation, buffer overflow conditions, or memory management errors that occur during graphics processing operations.
The operational impact of CVE-2016-4634 extends beyond simple privilege escalation to encompass potential system instability and unauthorized access to sensitive system resources. Local users who exploit this vulnerability could potentially execute arbitrary code with elevated privileges, effectively bypassing standard security controls and gaining access to protected system functions. The memory corruption aspect of the vulnerability could also lead to system crashes, rendering the affected system unusable and potentially causing data loss or system downtime. From an attacker's perspective, this vulnerability represents a valuable tool for achieving persistent access to target systems, as graphics drivers typically run continuously and maintain elevated privileges. The impact aligns with ATT&CK framework techniques such as privilege escalation through driver manipulation and defense evasion through system instability, making this vulnerability particularly dangerous in enterprise environments where local user access may be more prevalent.
Mitigation strategies for CVE-2016-4634 primarily focus on applying the official security patches released by Apple for macOS 10.11.6 and subsequent versions. System administrators should prioritize updating affected systems to ensure the graphics drivers receive the necessary security fixes that address the memory corruption issues. Additionally, implementing network segmentation and access controls can help limit the potential impact of local privilege escalation attacks by reducing the attack surface available to local users. Security monitoring should include detection of unusual graphics driver behavior or memory allocation patterns that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date system components, particularly those with direct hardware access such as graphics drivers, which are often overlooked in traditional security management approaches. Organizations should also consider implementing application whitelisting policies and restricting local user privileges where possible to minimize the potential damage from such local exploitation vectors. This vulnerability serves as a reminder of the critical need for comprehensive security practices that extend beyond traditional network-based protections to include system-level components that may be exploited by local attackers.