CVE-2016-4639 in Mac OS X
Summary
by MITRE
Login Window in Apple OS X before 10.11.6 does not properly initialize memory, which allows local users to cause a denial of service via unspecified vectors.
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Analysis
by VulDB Data Team • 09/30/2024
The vulnerability identified as CVE-2016-4639 affects Apple macOS versions prior to 10.11.6, specifically targeting the Login Window component that manages user authentication and system access. This issue represents a memory initialization flaw that can be exploited by local attackers to disrupt system operations. The vulnerability resides within the core authentication framework of the operating system, making it particularly concerning given its potential to impact system availability and user access to critical resources.
The technical flaw manifests in the improper initialization of memory structures within the Login Window application, which is responsible for handling user authentication processes. When the system attempts to process login requests, insufficient memory initialization can lead to unpredictable behavior including application crashes, system freezes, or complete denial of service conditions. This type of vulnerability falls under CWE-457, which specifically addresses the use of uninitialized variables, and represents a classic example of memory safety issues that can be exploited to cause system instability. The vulnerability does not require network connectivity or external exploitation, as it can be triggered through local system interactions, making it particularly dangerous in environments where local access is possible.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can potentially disrupt critical system functions and user productivity. Local attackers who can access the system may exploit this weakness to repeatedly crash the login window, forcing users to repeatedly restart authentication processes or potentially causing complete system lockouts. This vulnerability directly impacts the availability aspect of the system security triad and can be leveraged by malicious actors to create persistent disruptions. The attack surface is broad since any local user with access to the system can potentially trigger the vulnerability, making it particularly dangerous in multi-user environments or shared computing scenarios where unauthorized access might be possible.
Organizations should prioritize immediate patching of affected systems to address this vulnerability, as the remediation process is straightforward and involves updating to macOS version 10.11.6 or later. The fix implemented by Apple addresses the root cause by ensuring proper memory initialization within the Login Window component, thereby preventing the exploitation vectors that could lead to denial of service conditions. System administrators should also implement monitoring solutions to detect potential exploitation attempts and maintain regular security updates to prevent similar vulnerabilities from being exploited. Additionally, implementing proper access controls and user privilege management can help limit the potential impact of local exploitation attempts, aligning with the principle of least privilege as recommended in various security frameworks and standards. The vulnerability demonstrates the critical importance of proper memory management in system components and highlights the need for comprehensive security testing of authentication mechanisms.