CVE-2011-0182 in Mac OS X
Summary
by MITRE
The i386_set_ldt system call in the kernel in Apple Mac OS X before 10.6.7 does not properly handle call gates, which allows local users to gain privileges via vectors involving the creation of a call gate entry.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability described in CVE-2011-0182 represents a critical privilege escalation flaw within the kernel-level i386_set_ldt system call implementation in Apple Mac OS X versions prior to 10.6.7. This issue stems from improper handling of call gate entries during the process of setting up the Local Descriptor Table, which serves as a fundamental component of the x86 architecture's memory management and protection mechanisms. The vulnerability specifically manifests when local users attempt to create call gate entries through the i386_set_ldt system call, exploiting a weakness in the kernel's validation and processing of these specialized descriptor entries.
The technical flaw occurs because the kernel fails to properly validate or sanitize the parameters associated with call gate creation within the Local Descriptor Table structure. Call gates are special descriptor types that allow controlled transitions between different privilege levels, typically from user mode to kernel mode, and they require strict validation to prevent unauthorized privilege escalation. When the i386_set_ldt system call processes call gate entries, it does not adequately verify the integrity of the descriptor fields, particularly the segment selector and privilege level fields that control access permissions. This insufficient validation creates a pathway for malicious code to manipulate the call gate structure in ways that bypass normal kernel security controls and elevate privileges to root level.
The operational impact of this vulnerability is significant as it enables local attackers with minimal privileges to execute arbitrary code with kernel-level privileges, effectively compromising the entire system security model. The attack vector involves a local user creating a malicious call gate entry through the i386_set_ldt system call, which then allows the attacker to redirect execution flow to arbitrary code with elevated privileges. This privilege escalation capability undermines the fundamental security assumptions of the operating system's kernel protection mechanisms and could lead to complete system compromise. The vulnerability affects all Mac OS X versions before 10.6.7, making it particularly dangerous as it impacted a substantial user base of the operating system.
From a cybersecurity perspective, this vulnerability aligns with CWE-119 Improper Access Control and CWE-200 Information Exposure, as it represents a failure in proper privilege validation and a potential information disclosure mechanism. The vulnerability also maps to ATT&CK technique T1068, which covers legitimate credentials and privilege escalation paths, and T1059, which involves command and scripting interpreter usage for exploitation. The attack requires local system access and knowledge of kernel-level programming concepts, but once exploited, provides attackers with complete control over the target system. The vulnerability demonstrates the critical importance of proper kernel-level input validation and privilege boundary enforcement in preventing unauthorized access to system resources and maintaining the integrity of operating system security models.
Mitigation strategies for this vulnerability include immediate installation of Apple's security patches and updates, particularly the Mac OS X 10.6.7 update that addressed this specific issue. System administrators should also implement comprehensive monitoring for suspicious system calls related to i386_set_ldt and Local Descriptor Table modifications. The vulnerability highlights the necessity of kernel-level security hardening and proper input validation procedures. Organizations should maintain up-to-date patch management processes and consider implementing additional security controls such as kernel extension whitelisting and system integrity protection mechanisms to prevent exploitation of similar vulnerabilities. Regular security assessments of kernel-level components and proper privilege separation practices are essential to prevent similar privilege escalation attacks in the future.