CVE-2015-3677 in Mac OS X
Summary
by MITRE
The LZVN compression feature in AppleFSCompression in Apple OS X before 10.10.4 allows attackers to obtain sensitive memory-layout information for the kernel via a crafted app.
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Analysis
by VulDB Data Team • 05/22/2022
The vulnerability identified as CVE-2015-3677 resides within the AppleFSCompression component of Apple's operating system, specifically affecting macOS versions prior to 10.10.4. This issue manifests through the LZVN compression feature which is utilized for filesystem compression operations within the Apple File System. The flaw represents a significant information disclosure vulnerability that enables malicious actors to extract sensitive kernel memory layout information through carefully crafted applications. The vulnerability stems from insufficient input validation and memory handling within the compression algorithm implementation, creating an avenue for attackers to probe the kernel's memory structure through controlled data inputs.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious application that leverages the LZVN compression functionality in a manner designed to trigger memory disclosure behaviors. The compression library fails to properly validate the structure and content of compressed data streams, allowing crafted inputs to cause the system to reveal kernel memory addresses and layout information. This type of vulnerability falls under the CWE-20 category of "Improper Input Validation" and specifically relates to information exposure through memory disclosure mechanisms. The flaw operates at the kernel level within the Apple File System compression subsystem, making it particularly dangerous as it can provide attackers with critical information needed for more sophisticated exploitation techniques.
The operational impact of CVE-2015-3677 extends beyond simple information disclosure, as the revealed memory layout information can significantly aid in developing advanced persistent threats and kernel-level exploits. Attackers who successfully exploit this vulnerability can gain insights into kernel memory organization, which is essential for bypassing modern security mitigations such as address space layout randomization and kernel address space layout randomization. This information disclosure can be leveraged in conjunction with other vulnerabilities to enable privilege escalation attacks and kernel exploitation techniques. The vulnerability is particularly concerning because it affects the core filesystem compression functionality that is widely used throughout the operating system, making it a persistent threat vector that can be exploited through various legitimate application pathways.
Mitigation strategies for CVE-2015-3677 primarily involve updating to macOS version 10.10.4 or later, where Apple has implemented proper input validation and memory handling within the compression library. System administrators should also consider implementing additional monitoring and detection measures to identify potentially malicious applications that might attempt to exploit this vulnerability. The fix addresses the root cause by strengthening input validation mechanisms and ensuring that compressed data streams are properly sanitized before being processed by the kernel-level compression routines. This vulnerability demonstrates the importance of proper memory management and input validation in kernel-level components, aligning with ATT&CK technique T1068 which covers 'Local Privilege Escalation' and the broader category of kernel exploitation techniques. Organizations should also consider implementing application whitelisting policies and monitoring for unusual compression activities that might indicate exploitation attempts.