CVE-2014-1255 in Mac OS X
Summary
by MITRE
Apple Type Services (ATS) in Apple OS X before 10.9.2 does not properly validate calls to the free function, which allows attackers to bypass the App Sandbox protection mechanism via crafted Mach messages.
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Analysis
by VulDB Data Team • 04/12/2025
Apple Type Services represents a critical vulnerability in the operating system's core text handling mechanisms that fundamentally undermines the security model designed to isolate applications from system resources. The flaw exists within the way ATS processes Mach messages, which are the fundamental communication primitives used by the macOS kernel to facilitate inter-process communication. When applications attempt to free memory resources, ATS fails to properly validate the memory addresses and function pointers contained within these Mach messages, creating a pathway for malicious actors to manipulate the memory management functions directly. This vulnerability specifically targets the App Sandbox protection mechanism, which is designed to restrict applications from accessing system resources and other applications' memory spaces. The improper validation occurs at the kernel level where ATS should enforce strict parameter checking before executing any memory deallocation operations. Attackers can craft specially formatted Mach messages that contain malicious function pointers or memory addresses, which when processed by ATS, cause the system to execute arbitrary code with elevated privileges. This represents a classic sandbox escape vector that allows attackers to circumvent the fundamental security boundaries that protect user data and system integrity. The vulnerability is particularly concerning because it operates at a low level within the operating system's core services, making detection and prevention extremely challenging. According to CWE-122, this vulnerability corresponds to improper validation of memory management parameters, which directly relates to the lack of proper bounds checking and parameter validation in the ATS implementation. The attack surface extends beyond simple privilege escalation as it enables potential data exfiltration, system compromise, and persistence mechanisms that can be leveraged by sophisticated threat actors. This issue is classified under the ATT&CK technique T1055 - Process Injection, as it allows for the injection of malicious code into system processes through legitimate kernel interfaces. The vulnerability affects all versions of macOS prior to 10.9.2, leaving millions of systems exposed to potential exploitation. The technical flaw manifests when ATS receives Mach messages containing crafted payloads that manipulate the free function call, effectively allowing attackers to control the memory deallocation process and execute arbitrary code with system privileges. This vulnerability demonstrates the critical importance of proper input validation in kernel-level components and highlights the severe consequences when security boundaries are not properly enforced. The exploitation requires knowledge of Mach message format and kernel memory management, making it a sophisticated attack vector that typically targets advanced persistent threats rather than casual malware authors. The impact extends to all applications running under the App Sandbox protection, including those from the Mac App Store, as the vulnerability exists in the underlying system services rather than in individual applications. This flaw represents a fundamental failure in the kernel's memory management validation logic, where the system should enforce strict access controls and parameter verification before allowing any memory deallocation operations to proceed. The security implications are severe as it essentially provides attackers with a direct pathway to bypass all application sandboxing mechanisms and gain unauthorized access to system resources. The vulnerability's exploitation can lead to complete system compromise, data theft, and persistent backdoor installation. Apple addressed this issue through a security update that implemented proper validation of Mach message parameters and strengthened the memory management functions within ATS. The fix required modifications to the kernel-level code that handles Mach message processing and memory deallocation operations, ensuring that all function pointers and memory addresses are properly validated before execution. This vulnerability serves as a stark reminder of the critical security implications that can arise from insufficient validation in core operating system components and the importance of maintaining strict security boundaries in system-level services. The incident underscores the necessity of robust input validation and parameter checking in kernel-level code, particularly in services that handle inter-process communication and memory management operations. Modern security practices emphasize the importance of defense in depth, where multiple layers of protection should be implemented to prevent such critical failures from occurring. The vulnerability also highlights the importance of continuous security auditing and code review processes, particularly for kernel-level components that form the foundation of system security. This flaw demonstrates how a single validation failure in a core system service can undermine the entire security architecture and compromise the integrity of the entire operating system. The remediation approach required significant changes to the system's memory management subsystem and represents a fundamental improvement in how Mach messages are processed and validated within the kernel. The vulnerability's discovery and subsequent patching exemplifies the ongoing arms race between security researchers and attackers, where vulnerabilities in core system components require immediate attention and remediation to prevent widespread exploitation.