CVE-2013-6799 in Mac OS X
Summary
by MITRE
Apple Mac OS X 10.9 allows local users to cause a denial of service (memory corruption or panic) by creating a hard link to a directory. NOTE: this vulnerability exists because of an incomplete fix for CVE-2010-0105.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 12/28/2024
The vulnerability described in CVE-2013-6799 represents a significant flaw in Apple Mac OS X 10.9 that enables local attackers to trigger system instability through a specific file system manipulation technique. This issue stems from an incomplete remediation of a previously identified vulnerability, CVE-2010-0105, which demonstrates the complexity of addressing file system security weaknesses in operating systems. The vulnerability specifically targets the handling of hard links to directories within the macOS file system implementation, creating a scenario where legitimate system operations can be exploited to cause system-wide disruptions. This represents a classic example of how partial fixes can leave residual security gaps that attackers can leverage for denial of service attacks.
The technical root cause of this vulnerability lies in the kernel-level file system handling code that fails to properly validate directory hard link operations. When a local user creates a hard link to a directory, the system's file system layer does not adequately check the integrity of this operation, leading to memory corruption conditions that can result in kernel panics or system crashes. The flaw manifests in the way the operating system processes directory references and maintains file system metadata when hard links are created to directory objects. This type of memory corruption vulnerability falls under the CWE-119 category of "Improper Access to Memory" and can be classified as a kernel-level buffer overflow or memory management error that directly impacts system stability. The vulnerability operates at the kernel level, making it particularly dangerous as it can bypass user-space protections and directly affect the core operating system functionality.
The operational impact of this vulnerability extends beyond simple system crashes, as it provides attackers with a reliable method to disrupt system availability through a simple local operation. Local users who can execute commands on the system can exploit this flaw to cause repeated kernel panics, effectively rendering the system unstable and unusable for legitimate users. The attack requires minimal privileges since it operates locally and only requires the ability to create file system links, making it accessible to any user account on the system. This denial of service condition can be particularly problematic in enterprise environments where system uptime is critical, as attackers can repeatedly exploit this vulnerability to maintain persistent disruptions. The vulnerability also aligns with ATT&CK technique T1499.004 for "Endpoint Denial of Service" and demonstrates how file system manipulation can be weaponized for system compromise.
Mitigation strategies for this vulnerability should focus on both immediate system updates and operational security measures. The primary solution involves applying the official macOS security updates that contain the complete fix for this issue, which would address the underlying file system handling code that was inadequately patched in the previous remediation attempt. System administrators should prioritize patching affected systems and monitor for any signs of exploitation attempts, particularly in environments where multiple users have local access to systems. Additional protective measures include implementing strict file system access controls, monitoring for unusual hard link creation activities, and maintaining robust system monitoring to detect kernel panics or memory corruption events. The vulnerability highlights the importance of thorough vulnerability remediation processes and the need for comprehensive testing of security patches before deployment. Organizations should also consider implementing network segmentation and access control policies to limit local user privileges where possible, reducing the attack surface for such local privilege escalation and denial of service scenarios.