CVE-2016-1819 in iOS
Summary
by MITRE
Use-after-free vulnerability in the IOAccelContext2::clientMemoryForType method in Apple iOS before 9.3.2, OS X before 10.11.5, tvOS before 9.2.1, and watchOS before 2.2.1 allows attackers to execute arbitrary code in a privileged context or cause a denial of service (memory corruption) via a crafted app, a different vulnerability than CVE-2016-1817 and CVE-2016-1818.
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Analysis
by VulDB Data Team • 11/05/2024
The CVE-2016-1819 vulnerability represents a critical use-after-free condition within Apple's graphics acceleration subsystem, specifically affecting the IOAccelContext2::clientMemoryForType method. This flaw exists in multiple Apple operating systems including iOS versions prior to 9.3.2, macOS versions before 10.11.5, tvOS versions before 9.2.1, and watchOS versions before 2.2.1. The vulnerability stems from improper memory management where freed memory blocks are still referenced by subsequent operations, creating opportunities for malicious code execution. The issue manifests when a crafted application attempts to manipulate graphics memory contexts through the IOAccelerator framework, which is integral to Apple's graphics processing pipeline.
This use-after-free vulnerability operates at the kernel level within Apple's graphics driver architecture, making it particularly dangerous as it can be exploited to gain elevated privileges. The flaw occurs when the IOAccelContext2 object manages memory allocations for graphics processing tasks, specifically during the clientMemoryForType method execution. When memory is freed but not properly nullified, subsequent code references may access corrupted memory locations, leading to unpredictable behavior. Attackers can craft malicious applications that trigger the vulnerable code path, causing the system to execute arbitrary code with kernel privileges or induce system crashes through memory corruption. The vulnerability is classified under CWE-416 as a Use After Free condition, which is a common but severe class of memory safety issues.
The operational impact of CVE-2016-1819 extends beyond simple denial of service to include complete system compromise. An attacker with local application execution privileges can leverage this vulnerability to escalate privileges and gain root access to the affected system. The memory corruption can be exploited to overwrite critical kernel data structures, redirect execution flow, or inject malicious code into protected memory regions. This makes the vulnerability particularly attractive to advanced persistent threat actors and malware developers who seek to establish persistent access to target systems. The vulnerability's presence in multiple Apple platforms including mobile devices, desktop computers, and television systems creates a wide attack surface, potentially affecting millions of devices. The flaw is categorized under attack techniques such as privilege escalation and code injection within the MITRE ATT&CK framework.
Mitigation strategies for CVE-2016-1819 primarily involve applying official security patches from Apple, which address the underlying memory management issues in the IOAccelerator framework. System administrators should prioritize updating all affected Apple devices to the patched versions, particularly those running older operating system versions. Additional protective measures include implementing application sandboxing, monitoring for unusual memory access patterns, and deploying endpoint protection solutions that can detect exploitation attempts. Organizations should also consider network segmentation to limit the potential impact of successful exploitation and maintain regular security assessments of their Apple device fleets. The vulnerability highlights the importance of secure coding practices in kernel-level components and demonstrates how graphics acceleration subsystems can become attack vectors when proper memory management protocols are not followed.