CVE-2019-8634 in macOS
Summary
by MITRE
An authentication issue was addressed with improved state management. This issue is fixed in macOS Mojave 10.14.5. A user may be unexpectedly logged in to another user?s account.
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Analysis
by VulDB Data Team • 06/10/2020
The vulnerability described in CVE-2019-8634 represents a critical authentication flaw in macOS Mojave versions prior to 10.14.5, specifically related to improper state management during user session handling. This issue falls under the category of privilege escalation and unauthorized access, where an attacker could potentially gain access to another user's account without proper authentication credentials. The vulnerability exploits weaknesses in the operating system's session management mechanisms, allowing for unexpected account switching during active user sessions.
The technical root cause of this vulnerability stems from inadequate state management within the macOS authentication framework, particularly in how the system handles user session transitions and account switching operations. When a user logs out or when certain system events occur, the operating system should properly terminate the previous session and establish a clean state for the next user. However, the flaw allows for session state to persist incorrectly, enabling unauthorized access to another user's account. This issue is classified as a CWE-284 access control vulnerability, specifically related to improper privileges management and session handling. The vulnerability is particularly concerning because it operates at the system level, affecting the fundamental authentication mechanisms that protect user data and privacy.
The operational impact of CVE-2019-8634 extends beyond simple unauthorized access, potentially enabling attackers to access sensitive user data, modify files, execute commands, and compromise the confidentiality and integrity of the affected system. This vulnerability could be exploited by local attackers who have physical access to the machine or through more sophisticated attack vectors that leverage the authentication bypass to escalate privileges. The issue particularly affects environments where multiple users share the same system, making it a significant concern for enterprise environments, educational institutions, and any organization relying on multi-user macOS systems. From an attack perspective, this vulnerability aligns with ATT&CK technique T1078 legitimate credentials, as it allows unauthorized access using existing user accounts without requiring additional credential theft or cracking efforts.
Organizations affected by this vulnerability should immediately implement the recommended security patches provided by Apple, specifically upgrading to macOS Mojave 10.14.5 or later versions. System administrators should conduct comprehensive vulnerability assessments to identify any systems running vulnerable macOS versions and ensure all user sessions are properly terminated when switching between accounts. Additional mitigations include implementing strict physical security controls, monitoring user session activity, and establishing robust account management policies that require explicit logout procedures. The vulnerability demonstrates the critical importance of proper session management and state handling in operating system security frameworks, highlighting the need for continuous security testing and validation of authentication mechanisms. Organizations should also consider implementing additional monitoring solutions to detect unauthorized account access attempts and establish incident response procedures specifically tailored to address authentication-related security events.