CVE-2017-13907 in macOS
Summary
by MITRE • 12/23/2021
A state management issue was addressed with improved state validation. This issue is fixed in macOS High Sierra 10.13.1, Security Update 2017-001 Sierra, and Security Update 2017-004 El Capitan. The screen lock may unexpectedly remain unlocked.
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Analysis
by VulDB Data Team • 12/27/2021
The vulnerability identified as CVE-2017-13907 represents a critical state management flaw in Apple's macOS operating system that directly impacts the security posture of affected systems. This issue resides within the operating system's screen lock mechanism, where improper state validation allows for unexpected screen unlock conditions that can persist beyond normal security boundaries. The vulnerability specifically affects macOS High Sierra 10.13.0, as well as older versions Sierra and El Capitan, creating a persistent security risk for users who rely on screen locking as a primary access control mechanism. The root cause of this vulnerability stems from inadequate validation of the system's power state and screen lock status, allowing malicious actors or system anomalies to potentially bypass the intended security controls.
The technical implementation of this vulnerability demonstrates a failure in proper state machine management within the macOS security subsystem. When the system transitions between different power states or screen lock conditions, the validation mechanisms fail to properly verify that the screen lock has been successfully enforced. This flaw falls under the CWE-284 access control vulnerability category, specifically related to improper access control due to inadequate state management. The issue manifests when the system's internal state tracking becomes inconsistent, potentially allowing unauthorized access to the system when screen locking should be active. The vulnerability essentially creates a race condition or state inconsistency where the system believes the screen is locked while in reality it remains accessible to unauthorized users.
From an operational perspective, this vulnerability poses significant risks to organizations and individual users who depend on screen locking as a primary security control. The persistent nature of the issue means that once exploited, the screen lock may remain unlocked indefinitely, potentially allowing unauthorized access to sensitive data, applications, and system resources. Attackers could exploit this vulnerability by triggering specific system conditions that cause the state validation to fail, thereby maintaining access to the system without proper authentication. This vulnerability particularly impacts environments where physical security is paramount, such as corporate offices, government facilities, or any location where unauthorized access to computing resources could result in data breaches or system compromise. The security implications extend beyond simple unauthorized access, as the vulnerability could potentially enable further exploitation through privilege escalation or information disclosure attacks.
The remediation for CVE-2017-13907 was addressed through Apple's security updates released in late 2017, specifically targeting macOS High Sierra 10.13.1, Security Update 2017-001 for Sierra, and Security Update 2017-004 for El Capitan. These updates implemented improved state validation mechanisms that properly track and enforce screen lock conditions throughout system transitions. Organizations should prioritize applying these security updates immediately to mitigate the risk of unauthorized access. Additionally, system administrators should consider implementing supplementary security measures such as automatic screen locking policies, enhanced monitoring of screen lock states, and regular security assessments to identify potential state management issues. The vulnerability serves as a reminder of the critical importance of proper state management in security-critical systems and aligns with ATT&CK technique T1070.004 for indicator removal and T1547.001 for registry run keys to maintain persistent access. Organizations should also review their security policies to ensure that screen locking is properly enforced and monitored, particularly in high-risk environments where physical access controls are essential for maintaining overall security posture.