CVE-2016-4621 in Mac OS X
Summary
by MITRE
libc++abi in Apple OS X before 10.11.6 allows attackers to execute arbitrary code in a privileged context or cause a denial of service (memory corruption) via a crafted app.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 09/30/2024
The vulnerability identified as CVE-2016-4621 affects the libc++abi library component within Apple's macOS operating system versions prior to 10.11.6. This issue represents a critical security flaw that exists within the C++ standard library's exception handling mechanisms, specifically within the C++ ABI (Application Binary Interface) implementation. The vulnerability stems from improper handling of exception objects during the unwinding process, creating a pathway for malicious actors to exploit memory corruption weaknesses in the system's runtime environment.
The technical flaw manifests through a buffer overflow condition that occurs when the system processes malformed exception objects within the libc++abi library. When a crafted application attempts to throw and handle exceptions in a specific manner, the library fails to properly validate the size and structure of exception metadata, leading to memory corruption that can be leveraged for arbitrary code execution. This vulnerability operates at the kernel level execution context, allowing attackers to escalate privileges and execute malicious code with the same permissions as the target process, which typically runs with elevated privileges. The flaw is classified under CWE-121 as a stack-based buffer overflow, though it operates in a more complex memory management context within the C++ runtime environment.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can be exploited to achieve complete system compromise when combined with other attack vectors. An attacker who successfully exploits this vulnerability can execute arbitrary code in a privileged context, effectively bypassing standard security controls and potentially gaining access to sensitive system resources, user data, and network communications. The memory corruption aspect also presents a denial of service risk, where the targeted system may crash or become unresponsive due to corrupted memory structures, making the vulnerability particularly dangerous in enterprise environments where system stability is paramount. This weakness aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1499 which addresses 'Endpoint Denial of Service'.
Mitigation strategies for CVE-2016-4621 primarily focus on applying the official security patches released by Apple as part of macOS 10.11.6 updates. System administrators should prioritize immediate deployment of these patches across all affected systems, particularly in environments where the targeted applications might be exposed to untrusted input or potentially malicious applications. Additional protective measures include implementing application sandboxing policies that limit the execution of untrusted code, monitoring for unusual exception handling patterns that might indicate exploitation attempts, and maintaining comprehensive system logging to detect potential abuse of the vulnerability. Organizations should also consider network segmentation and access controls to limit the potential impact if an attacker successfully exploits this vulnerability, while ensuring that all development environments are updated to prevent the introduction of vulnerable code. The vulnerability demonstrates the critical importance of maintaining up-to-date system libraries and the potential risks associated with runtime environment flaws that can be exploited across multiple applications and system components.