CVE-2015-6989 in Mac OS X
Summary
by MITRE
Grand Central Dispatch in Apple iOS before 9.1, OS X before 10.11.1, and watchOS before 2.0.1 allows attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted package that is mishandled during dispatch calls.
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Analysis
by VulDB Data Team • 11/19/2024
The vulnerability identified as CVE-2015-6989 represents a critical memory corruption flaw within Apple's Grand Central Dispatch (GCD) framework that affected multiple operating systems including iOS versions prior to 9.1, macOS versions before 10.11.1, and watchOS versions before 2.0.1. This issue resides in the core concurrency management system that Apple uses to handle asynchronous operations and task scheduling across its platforms. The vulnerability stems from improper handling of crafted packages during dispatch calls, creating a pathway for attackers to exploit memory management inconsistencies within the GCD subsystem. The flaw specifically manifests when the system processes malformed or specially crafted packages that are intended to be dispatched for execution, leading to unpredictable memory state corruption that can be leveraged for privilege escalation.
From a technical perspective, this vulnerability operates at the intersection of memory management and concurrency control within Apple's operating systems, making it particularly dangerous due to its potential for arbitrary code execution. The GCD framework serves as a fundamental component for parallel processing and task management across Apple's ecosystem, handling everything from user interface updates to background processing tasks. When attackers submit maliciously crafted packages designed to exploit the dispatch mechanism, the system's memory corruption occurs during the internal processing of these packages, potentially leading to stack or heap corruption that can be manipulated to execute arbitrary code. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow conditions, both of which are common precursors to privilege escalation attacks.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it provides attackers with the capability to achieve arbitrary code execution on affected systems. Attackers can potentially leverage this vulnerability to escalate privileges and gain unauthorized access to system resources, making it particularly concerning for enterprise environments and users who rely on Apple devices for sensitive operations. The memory corruption aspect of this vulnerability means that exploitation could lead to system instability, crashes, or more sinister outcomes such as persistent backdoor installation. The attack surface is broad due to the widespread use of GCD across various applications and system processes, making any application that utilizes dispatch functionality a potential target for exploitation. Organizations and individuals running affected versions of Apple operating systems face significant risk of compromise, as the vulnerability can be triggered through various attack vectors including email attachments, malicious websites, or compromised applications.
Mitigation strategies for CVE-2015-6989 primarily focus on applying official security updates from Apple, which address the underlying memory handling issues in the GCD framework. System administrators should prioritize patching affected systems and ensuring all devices are updated to the latest versions of iOS, macOS, and watchOS that contain the necessary security fixes. Additionally, organizations should implement network monitoring to detect potential exploitation attempts and maintain robust incident response procedures. The vulnerability's nature suggests that defensive measures should include runtime protection mechanisms and application sandboxing to limit the potential impact of successful exploitation attempts. Security teams should also consider implementing behavioral monitoring to detect anomalous dispatch activity that might indicate exploitation attempts. According to ATT&CK framework methodology, this vulnerability would map to techniques involving privilege escalation and code execution through system-level components, making it a critical target for both preventive and detective security controls. The remediation process should also include thorough testing of patches in controlled environments to ensure compatibility with existing applications and system configurations.