CVE-2016-7621 in watchOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 10.2 is affected. macOS before 10.12.2 is affected. watchOS before 3.1.3 is affected. The issue involves the "Kernel" component. It allows local users to execute arbitrary code in a privileged context or cause a denial of service (use-after-free) via unspecified vectors.
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Analysis
by VulDB Data Team • 09/22/2024
The vulnerability identified as CVE-2016-7621 represents a critical use-after-free flaw within the kernel component of multiple Apple operating systems including iOS, macOS, and watchOS. This type of vulnerability occurs when a program continues to access memory that has already been freed, creating opportunities for malicious code execution or system instability. The affected versions include iOS versions prior to 10.2, macOS versions prior to 10.12.2, and watchOS versions prior to 3.1.3, indicating a widespread impact across Apple's ecosystem. The kernel component serves as the core of the operating system, managing system resources and providing essential services, making any vulnerability in this area particularly dangerous as it can provide attackers with elevated privileges and system control.
The technical nature of this use-after-free vulnerability stems from improper memory management within the kernel's implementation. When the kernel allocates and deallocates memory blocks, a flaw in the reference counting or memory tracking mechanisms allows for a situation where an attacker can manipulate the system to access memory that should have been freed. This memory access pattern creates opportunities for arbitrary code execution within the privileged kernel context, potentially enabling attackers to bypass security restrictions and gain unauthorized access to system resources. The unspecified vectors suggest that multiple attack surfaces within the kernel could be exploited, making the vulnerability particularly challenging to defend against as it may be reachable through various legitimate system functions or interfaces.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can lead to complete system compromise and persistent backdoor access. Local users with minimal privileges can exploit this flaw to execute malicious code with kernel-level permissions, potentially allowing them to modify system files, install persistent malware, or create unauthorized user accounts. The vulnerability also presents a denial of service risk, where a carefully crafted exploit could cause system crashes or reboot loops, disrupting normal operations. From a cybersecurity perspective, this vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions, and represents a significant weakness in Apple's memory management implementation that could be leveraged by sophisticated attackers to establish persistent footholds within affected systems.
Mitigation strategies for CVE-2016-7621 primarily focus on applying the relevant security updates provided by Apple, which include kernel patches that correct the memory management flaws. Organizations should prioritize immediate deployment of iOS 10.2, macOS 10.12.2, and watchOS 3.1.3 updates across all affected devices to eliminate the vulnerability. System administrators should also implement additional security measures such as monitoring for unusual kernel activity, network segmentation to limit lateral movement, and regular security assessments to identify potential exploitation attempts. The vulnerability demonstrates the critical importance of timely patch management and the need for organizations to maintain robust update processes for all operating systems and applications. From an ATT&CK framework perspective, this vulnerability could map to techniques such as privilege escalation and persistence, with potential TTPs including kernel rootkits and system modification. Organizations should also consider implementing endpoint detection and response solutions to identify and block exploitation attempts, as the use-after-free nature of the vulnerability may leave detectable artifacts in system memory or network traffic patterns.