CVE-2016-4638 in Mac OS X
Summary
by MITRE
Login Window in Apple OS X before 10.11.6 allows attackers to gain privileges via a crafted app that leverages a "type confusion."
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Analysis
by VulDB Data Team • 10/01/2024
The vulnerability identified as CVE-2016-4638 represents a critical privilege escalation flaw within the login window component of Apple macOS operating systems prior to version 10.11.6. This issue specifically targets the authentication mechanism that governs user access to the system, creating a pathway for malicious actors to bypass normal security controls and elevate their privileges. The vulnerability manifests through a type confusion error that occurs during the processing of crafted applications, fundamentally undermining the integrity of the system's authentication framework. Type confusion vulnerabilities typically arise when a program incorrectly handles data types, leading to unpredictable behavior that can be exploited by attackers to manipulate program execution flow.
The technical exploitation of this vulnerability relies on a carefully constructed malicious application that can manipulate the login window's internal type handling mechanisms. When such an application is processed by the system, the type confusion error causes the program to interpret data in unexpected ways, potentially allowing the attacker to inject malicious code or manipulate authentication states. This flaw operates at a fundamental level within the operating system's security architecture, specifically targeting the login window interface that serves as the primary entry point for user authentication. The vulnerability's impact extends beyond simple unauthorized access, as successful exploitation can result in full system compromise and persistent administrative privileges. According to CWE classification, this represents a type confusion vulnerability (CWE-128) that falls under the broader category of improper type handling, which is a well-documented weakness in software security.
The operational impact of CVE-2016-4638 is significant for organizations and individual users running affected versions of macOS, as it provides a direct route to privilege escalation without requiring additional attack vectors. Attackers can leverage this vulnerability to gain root access to systems, potentially leading to data exfiltration, persistent backdoor installation, or further network reconnaissance activities. The vulnerability's stealth nature makes it particularly dangerous, as the malicious application can be designed to appear legitimate while simultaneously exploiting the type confusion flaw. From an attacker's perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under privilege escalation tactics, specifically targeting the login process as an entry point for system compromise. The vulnerability affects the core authentication infrastructure of macOS, making it a high-value target for threat actors seeking persistent access to compromised systems.
Mitigation strategies for CVE-2016-4638 primarily focus on updating to Apple macOS version 10.11.6 or later, which includes patches addressing the type confusion vulnerability in the login window component. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive timely updates, as the vulnerability can be exploited remotely or through social engineering tactics. Additional protective measures include monitoring for suspicious application installations and implementing application whitelisting policies to prevent unauthorized software execution. System administrators should also consider enabling security features such as System Integrity Protection (SIP) that was strengthened in subsequent macOS releases to provide additional layers of defense against privilege escalation attacks. The vulnerability underscores the importance of maintaining current operating system versions and highlights the critical need for proactive security maintenance to protect against known exploits that target fundamental system components.