CVE-2017-13887 in macOS
Summary
by MITRE
In macOS High Sierra before 10.13.2, a logic issue existed in APFS when deleting keys during hibernation. This was addressed with improved state management.
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Analysis
by VulDB Data Team • 04/28/2020
The vulnerability identified as CVE-2017-13887 represents a critical logic flaw within the Apple File System (APFS) implementation in macOS High Sierra versions prior to 10.13.2. This issue specifically manifests during the hibernation process when the system attempts to delete cryptographic keys from memory, creating a potential security risk that could be exploited by malicious actors. The flaw stems from inadequate state management within the APFS subsystem, which governs how data is stored and retrieved on modern Apple devices including Mac computers, iPhones, and iPads. When a system enters hibernation mode and subsequently attempts to clean up cryptographic keys used for encryption, the improper handling of these key deletion operations creates a window where sensitive data could remain accessible or where the system could enter an inconsistent state. This vulnerability directly impacts the security model of macOS systems that rely on APFS for encrypted storage, potentially allowing unauthorized access to encrypted data or compromising the integrity of the encryption keys themselves. The issue falls under the category of improper state management as classified by CWE-362, which deals with concurrent execution using shared resources without proper synchronization mechanisms. From an operational perspective, this vulnerability could enable attackers to exploit the inconsistent state of key deletion during hibernation, potentially leading to data exposure or system compromise. The security implications extend beyond simple data access, as the improper handling of cryptographic keys during system transitions could undermine the entire encryption framework that protects user data. This flaw aligns with ATT&CK technique T1003.003 which involves OS credential dumping, as compromised key management during hibernation could provide attackers with access to encryption keys used for system protection. The vulnerability demonstrates a fundamental flaw in how APFS manages cryptographic state transitions, particularly during power state changes where systems must reliably handle sensitive data cleanup operations. The root cause lies in the insufficient validation and management of key deletion operations within the hibernation context, creating a potential attack surface that could be leveraged for privilege escalation or data theft. System administrators and security professionals should recognize that this vulnerability affects not just individual user data but also the overall integrity of the macOS security architecture, particularly in enterprise environments where data protection is paramount. The fix implemented by Apple in version 10.13.2 addresses the core issue through enhanced state management protocols that ensure proper cleanup of cryptographic keys during hibernation cycles, thereby preventing the logic error that previously allowed for potential exploitation. This remediation demonstrates the importance of proper state management in cryptographic systems and highlights the need for robust handling of sensitive data during system transitions. The vulnerability serves as a reminder of the critical nature of secure key management in modern operating systems, where improper handling of encryption keys during routine operations like hibernation can create significant security risks. Organizations should prioritize updating to affected systems to prevent potential exploitation of this logic flaw that could compromise the confidentiality and integrity of encrypted data stored on affected macOS devices.