CVE-2015-6983 in Mac OS X
Summary
by MITRE
Double free vulnerability in Apple iOS before 9.1 and OS X before 10.11.1 allows attackers to write to arbitrary files via a crafted app that accesses AtomicBufferedFile descriptors.
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Analysis
by VulDB Data Team • 11/21/2024
The CVE-2015-6983 vulnerability represents a critical double free condition affecting Apple iOS versions prior to 9.1 and OS X versions prior to 10.11.1. This flaw exists within the handling of AtomicBufferedFile descriptors, which are used for atomic file operations in the operating system's file management subsystem. The vulnerability stems from improper memory management where the same memory block gets freed twice during the processing of file operations, creating a predictable memory corruption scenario that can be exploited by malicious applications.
The technical implementation of this vulnerability involves the manipulation of file descriptor handling within the kernel-level file system operations. When a crafted application attempts to access AtomicBufferedFile descriptors, the system fails to properly validate or track the memory references associated with these file operations. This leads to a scenario where the same memory chunk is deallocated twice, potentially allowing an attacker to control the memory layout and redirect execution flow. The vulnerability is classified as a CWE-415 Double Free, which is a well-documented weakness in memory management where the same memory location is freed more than once.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with the capability to write to arbitrary files on the system. This arbitrary file write capability can be leveraged to modify system binaries, install malicious software, or compromise the integrity of the operating system. The attack vector requires a crafted application that can trigger the specific sequence of file operations leading to the double free condition, making it a targeted exploit rather than a broad-based vulnerability. The vulnerability falls under the ATT&CK technique T1059 Command and Scripting Interpreter and T1070 Indicator Removal on Host, as it can be used to establish persistence and hide malicious activities through file system modifications.
Mitigation strategies for CVE-2015-6983 primarily involve updating to the patched versions of iOS 9.1 and OS X 10.11.1, which contain memory management fixes that prevent the double free condition from occurring. System administrators should implement comprehensive patch management policies to ensure all devices are updated promptly. Additionally, monitoring for suspicious file system activities and implementing application whitelisting can help detect and prevent exploitation attempts. The vulnerability demonstrates the critical importance of proper memory management in operating system kernels and highlights the need for robust input validation and resource tracking mechanisms. Organizations should also consider implementing sandboxing techniques and privilege separation to limit the potential impact of such vulnerabilities even when present in the system.