CVE-2008-3609 in Mac OS X
Summary
by MITRE
The kernel in Apple Mac OS X 10.5 through 10.5.4 does not properly flush cached credentials during recycling (aka purging) of a vnode, which might allow local users to bypass the intended read or write permissions of a file.
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Analysis
by VulDB Data Team • 05/31/2025
The vulnerability described in CVE-2008-3609 represents a critical credential caching flaw within the kernel of Apple Mac OS X versions 10.5 through 10.5.4. This issue stems from improper handling of vnode recycling processes where cached credentials fail to be adequately flushed when file system objects are purged from memory. The vulnerability operates at the kernel level, exploiting fundamental memory management mechanisms that govern how file system metadata and access control information are maintained in system cache. From a security perspective, this represents a privilege escalation vector that allows local attackers to bypass intended file access controls through manipulation of the credential caching system.
The technical implementation of this vulnerability involves the kernel's vnode management subsystem where file system objects are cached in memory for performance optimization purposes. When these cached vnodes undergo the recycling process, the system should properly invalidate or flush associated credential information to prevent unauthorized access. However, the flaw occurs during this purging operation where stale credentials remain cached, enabling attackers to leverage these outdated permissions. This behavior aligns with CWE-200, which addresses improper exposure of sensitive information, and specifically relates to credential management within kernel space. The vulnerability exploits the fundamental assumption that cached credentials should be invalidated when their associated file system objects are recycled, creating a window where stale access rights persist beyond their intended lifecycle.
From an operational standpoint, this vulnerability enables local users to gain unauthorized access to files that should normally be restricted based on their read or write permissions. The impact extends beyond simple privilege escalation as it undermines the entire file system access control model that Mac OS X implements. Attackers can potentially read sensitive data, modify protected files, or execute unauthorized operations on system resources that should be inaccessible. The vulnerability is particularly concerning because it operates silently within the kernel, making detection difficult and allowing persistent unauthorized access. This type of flaw falls under ATT&CK technique T1068, which covers local privilege escalation through kernel exploits, and demonstrates how memory management weaknesses can be leveraged to circumvent security controls.
The mitigation strategies for this vulnerability require immediate system updates to patched versions of Mac OS X, as Apple would have addressed the credential flushing mechanism in subsequent releases. System administrators should implement comprehensive patch management processes to ensure all affected systems receive the necessary security updates. Additionally, monitoring for unusual file access patterns and implementing enhanced logging of file system operations can help detect exploitation attempts. The vulnerability highlights the importance of proper cache invalidation mechanisms in kernel space and demonstrates how seemingly minor memory management flaws can have significant security implications. Organizations should also consider implementing additional access control measures such as mandatory access controls or enhanced auditing to provide defense-in-depth against similar credential-based vulnerabilities that may exist in other system components.