CVE-2014-4375 in Mac OS X
Summary
by MITRE
Double free vulnerability in Apple iOS before 8 and Apple TV before 7 allows local users to gain privileges or cause a denial of service (device crash) via vectors related to Mach ports.
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Analysis
by VulDB Data Team • 02/23/2022
The CVE-2014-4375 vulnerability represents a critical double free error in Apple's operating systems that affected iOS versions prior to 8 and Apple TV versions prior to 7. This vulnerability resides in the kernel-level handling of Mach ports, which are fundamental communication mechanisms used by the operating system for inter-process communication and system service access. The flaw occurs when the kernel improperly manages memory allocation and deallocation processes during Mach port operations, creating conditions where the same memory block can be freed twice. This memory corruption issue arises from inadequate validation of port reference counts and improper handling of port cleanup routines within the kernel's Mach port subsystem.
The technical exploitation of this vulnerability leverages the inherent design of Mach ports within the XNU kernel to create a scenario where a local attacker can manipulate port reference counters to trigger the double free condition. When the kernel attempts to free memory associated with Mach ports, it processes the same memory block multiple times due to flawed reference counting logic. This occurs during normal port disposal operations when the kernel fails to properly track port usage and cleanup sequences. The vulnerability is particularly dangerous because it operates at the kernel level where privilege escalation is possible, allowing local users to potentially execute arbitrary code with system-level privileges. The flaw can be triggered through malicious applications that create and manipulate Mach ports in specific sequences designed to exploit the reference counting race condition.
The operational impact of CVE-2014-4375 extends beyond simple denial of service scenarios to encompass serious privilege escalation capabilities. Local attackers can leverage this vulnerability to execute code with kernel-level privileges, potentially compromising the entire device and enabling persistent access to sensitive data and system resources. The device crash resulting from the double free condition represents the most common exploitation outcome, but the underlying memory corruption opens pathways for more sophisticated attacks including system takeover and data exfiltration. This vulnerability directly maps to CWE-415, which describes improper behavior in memory management where a program attempts to free the same memory block twice, and aligns with ATT&CK technique T1068 which covers local privilege escalation through kernel exploits. The attack surface is particularly concerning as it requires no special privileges or external network access, making it exploitable through local applications that can manipulate Mach port operations.
Mitigation strategies for CVE-2014-4375 primarily involve applying official security updates from Apple that address the underlying kernel memory management issues. System administrators should ensure immediate deployment of iOS 8 and Apple TV 7 updates which contain patches for the Mach port handling logic. The fixes typically involve strengthening reference counting mechanisms and implementing proper memory deallocation procedures within the kernel's Mach port subsystem. Organizations should also consider implementing additional security controls such as application whitelisting to prevent malicious applications from creating exploitable port manipulation scenarios. Network monitoring solutions should be configured to detect anomalous Mach port usage patterns that might indicate exploitation attempts. Regular security assessments of iOS and Apple TV environments should include verification of patch compliance and monitoring for signs of kernel-level memory corruption. The vulnerability highlights the importance of proper memory management practices in kernel code and serves as a reminder of the critical security implications of improper resource handling in operating system components.