CVE-2008-4218 in Mac OS X
Summary
by MITRE
Multiple integer overflows in the kernel in Apple Mac OS X before 10.5.6 on Intel platforms allow local users to gain privileges via a crafted call to (1) i386_set_ldt or (2) i386_get_ldt.
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Analysis
by VulDB Data Team • 08/22/2019
The vulnerability described in CVE-2008-4218 represents a critical security flaw in Apple Mac OS X kernel implementations prior to version 10.5.6 on Intel platforms. This issue manifests through integer overflow conditions that occur during specific kernel system calls, creating opportunities for privilege escalation attacks. The vulnerability specifically affects the i386_set_ldt and i386_get_ldt functions, which are responsible for managing local descriptor tables in the x86 architecture. These functions handle memory management operations that are fundamental to operating system security and process isolation. The integer overflows occur when the kernel fails to properly validate input parameters, particularly when processing user-supplied values that are used to calculate array indices or buffer sizes. This flaw falls under the CWE-190 category of Integer Overflow or Wraparound, which is a well-documented weakness in software security where arithmetic operations produce values that exceed the maximum representable value for the data type. The vulnerability is particularly dangerous because it resides within the kernel space, meaning that successful exploitation can lead to complete system compromise and privilege escalation from user-level processes to kernel-level privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with the ability to execute arbitrary code with the highest system privileges. When local users can manipulate the i386_set_ldt and i386_get_ldt system calls, they can potentially overflow integer values to manipulate kernel memory structures or bypass security checks. This creates a pathway for attackers to modify critical system components, install rootkits, or gain persistent access to the compromised system. The attack vector requires local access to the system, but this is often achievable through various social engineering techniques or by exploiting other vulnerabilities that provide initial access. The vulnerability's presence in the kernel means that any successful exploitation can result in complete system takeover, as the attacker gains the ability to manipulate memory, execute code, and potentially access all system resources. This aligns with the ATT&CK framework's privilege escalation techniques, particularly those that involve kernel exploits and system call manipulation.
Mitigation strategies for CVE-2008-4218 primarily focus on updating to Apple Mac OS X 10.5.6 or later versions where the integer overflow issues have been patched. System administrators should also implement proper access controls and monitoring to detect potential exploitation attempts, as the vulnerability requires local system access to exploit. The patched versions include proper input validation and integer overflow protection mechanisms that prevent malicious values from causing the kernel to compute invalid memory addresses or manipulate critical data structures. Additionally, organizations should conduct regular security assessments and maintain up-to-date system patches to prevent similar vulnerabilities from being exploited. The fix typically involves implementing bounds checking for input parameters and ensuring that integer arithmetic operations do not produce values that exceed the maximum representable range for the target data types. This vulnerability demonstrates the critical importance of kernel security and proper input validation in preventing privilege escalation attacks, as even seemingly minor flaws in system calls can lead to complete system compromise.