CVE-2014-4438 in Mac OS X
Summary
by MITRE
Race condition in LoginWindow in Apple OS X before 10.10 allows physically proximate attackers to obtain access by leveraging an unattended workstation on which screen locking had been attempted.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 02/23/2022
The vulnerability identified as CVE-2014-4438 represents a critical race condition flaw within the LoginWindow component of Apple's macOS operating system affecting versions prior to 10.10. This security weakness arises from the improper handling of screen locking mechanisms during the transition between active user sessions and locked states. The vulnerability specifically exploits the timing window between when a user initiates a screen lock and when the system fully transitions to the locked state, creating an opportunity for unauthorized access.
The technical implementation of this race condition occurs within the LoginWindow service which manages the graphical login interface and screen locking functionality. When a user attempts to lock their workstation, the system undergoes a sequence of operations that includes terminating active sessions, switching to the login screen, and establishing the locked state. However, due to insufficient synchronization mechanisms, there exists a brief window where the system may appear locked while still maintaining active session components that can be exploited. This timing discrepancy allows an attacker with physical proximity to the device to potentially bypass the lock mechanism and gain access to the system.
The operational impact of this vulnerability is significant for organizations and individual users who rely on screen locking as a primary security control. Attackers can exploit this weakness by approaching an unattended workstation that has been in the process of locking but has not yet completed the transition. The vulnerability is particularly dangerous because it requires minimal sophistication and can be exploited by anyone with physical access to the device. This makes it especially concerning for environments where security is paramount, such as corporate offices, government facilities, or any location where unauthorized access to sensitive information could result in substantial damage.
The vulnerability aligns with CWE-367, which describes Time-of-Check to Time-of-Use (TOCTOU) flaws, and demonstrates how improper state management can create exploitable conditions in security-critical components. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and privilege escalation, as it allows adversaries to bypass authentication mechanisms that should prevent unauthorized access. The attack vector is classified as physical proximity, which represents a significant threat in environments where social engineering or opportunistic attacks are possible. Organizations should consider this vulnerability as part of their broader security posture assessment, particularly in environments where unattended devices are common.
Mitigation strategies for CVE-2014-4438 primarily involve upgrading to macOS version 10.10 or later, which includes fixes addressing the race condition in the LoginWindow component. System administrators should implement mandatory screen locking policies and ensure that all devices are configured to lock immediately upon screen inactivity. Additional protective measures include enabling automatic updates, implementing strong physical security controls for workstations, and educating users about the importance of manually locking their screens even when they step away from their devices. Organizations should also consider implementing additional security controls such as automatic screen dimming, device encryption, and network-based access controls to provide layered protection against this type of vulnerability. The fix implemented in macOS 10.10 addresses the underlying synchronization issues in the LoginWindow service, ensuring that the transition to locked state occurs atomically without leaving exploitable gaps in the security model.