CVE-2007-4684 in Mac OS X
Summary
by MITRE
Integer overflow in the kernel in Apple Mac OS X 10.4 through 10.4.10 allows local users to execute arbitrary code via a large num_sels argument to the i386_set_ldt system call.
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Analysis
by VulDB Data Team • 03/15/2025
The vulnerability described in CVE-2007-4684 represents a critical integer overflow condition within the kernel of Apple Mac OS X versions 10.4 through 10.4.10. This flaw exists in the i386_set_ldt system call which is responsible for managing the local descriptor table in x86 architecture systems. The vulnerability specifically manifests when a local attacker provides an excessively large num_sels argument to this system call, creating a scenario where integer arithmetic exceeds the maximum representable value for the data type used in the kernel implementation. This type of vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which is a well-documented weakness in software security that occurs when an integer value is incremented beyond its maximum limit and wraps around to a small or negative value. The operational impact of this vulnerability is severe as it allows local users to escalate privileges and execute arbitrary code with kernel-level privileges, effectively bypassing the system's security model and potentially compromising the entire operating system.
The technical exploitation of this vulnerability requires a local user to have access to the system and the ability to execute code within the context of the operating system. The integer overflow specifically occurs in the kernel's handling of the num_sels parameter which determines the number of selector entries to be set in the local descriptor table. When this parameter exceeds the maximum value that can be represented by the underlying integer data type, the overflow causes unpredictable behavior in the kernel memory management routines. The system call implementation fails to properly validate the input parameter before performing arithmetic operations or memory allocations, leading to a situation where the kernel may allocate insufficient memory or corrupt existing memory structures. This memory corruption can then be leveraged by an attacker to manipulate kernel data structures or overwrite critical function pointers, ultimately enabling code execution with the highest privilege level. The vulnerability is particularly dangerous because it operates within kernel space, meaning that successful exploitation bypasses all user-space security mechanisms and can result in complete system compromise.
The implications of this vulnerability extend beyond simple privilege escalation as it represents a fundamental flaw in the kernel's input validation and memory management processes. According to the ATT&CK framework, this vulnerability could be categorized under privilege escalation techniques, specifically leveraging kernel vulnerabilities to gain root access. The attack vector requires local system access, making it particularly concerning for environments where multiple users share systems or where the operating system is deployed in multi-user configurations. From a security perspective, this vulnerability demonstrates the critical importance of proper integer overflow protection in kernel code, as even a single unvalidated parameter can provide a complete path to system compromise. The vulnerability's impact is amplified by the fact that it affects a wide range of Mac OS X versions, making it a significant concern for system administrators who must maintain multiple affected systems. The exploitation of such vulnerabilities often leads to persistent backdoors or additional compromise vectors, as attackers who gain kernel-level access can modify system files, disable security mechanisms, or establish covert communication channels.
Mitigation strategies for CVE-2007-4684 focus on both immediate patching and system hardening measures. Apple addressed this vulnerability through the release of security updates that included proper input validation and bounds checking for the num_sels parameter in the i386_set_ldt system call. System administrators should immediately apply the relevant security patches to all affected Mac OS X systems to prevent exploitation. Additionally, implementing proper access controls and limiting local user privileges can reduce the attack surface, as the vulnerability requires local access to execute. Monitoring for unusual system calls or memory allocation patterns may help detect exploitation attempts, though such detection is challenging given the kernel-level nature of the vulnerability. The vulnerability also highlights the importance of regular security assessments and code reviews focusing on kernel components, particularly around integer handling and input validation. Organizations should consider implementing automated patch management systems to ensure timely deployment of security updates and maintain comprehensive system inventory to identify all affected systems. The incident serves as a reminder of the critical need for robust software security practices in operating system kernels where even subtle flaws can result in complete system compromise.