CVE-2018-4176 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13.4 is affected. The issue involves the "Disk Images" component. It allows attackers to trigger an app launch upon mounting a crafted disk image.
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Analysis
by VulDB Data Team • 02/07/2021
The vulnerability identified as CVE-2018-4176 represents a significant security flaw within Apple's macOS operating system affecting versions prior to 10.13.4. This issue resides within the Disk Images component which is responsible for handling various types of disk image files including those used for software distribution and data storage. The vulnerability specifically targets the automatic mounting behavior of disk images and exploits a design weakness that allows malicious actors to craft specially formatted disk images capable of triggering unauthorized application execution. The flaw demonstrates how seemingly benign file handling operations can be leveraged for malicious purposes, creating a vector for privilege escalation and potential system compromise.
The technical implementation of this vulnerability stems from insufficient validation of disk image metadata during the mounting process. When a user mounts a crafted disk image, the system automatically processes certain metadata fields that can contain executable commands or references to applications that should not be launched without explicit user consent. This behavior aligns with CWE-787 which describes out-of-bounds writes and related issues that can occur when systems fail to properly validate input data. The vulnerability specifically enables attackers to manipulate the automatic execution behavior of disk images through carefully constructed metadata that bypasses normal security controls. The flaw operates at the system level where the disk image mounting process does not properly sanitize or validate the content that triggers application launches, creating an environment where malicious payloads can execute without user interaction.
The operational impact of CVE-2018-4176 extends beyond simple unauthorized execution of applications as it represents a potential pathway for more sophisticated attacks. Attackers can leverage this vulnerability to deliver malware payloads through seemingly legitimate disk images that users might encounter during normal operations such as software updates, system recovery images, or third-party distribution media. The vulnerability can be particularly dangerous in enterprise environments where users may mount disk images from untrusted sources or where automated mounting features are enabled. This issue directly maps to several techniques described in the MITRE ATT&CK framework under the category of "Execution" and "Persistence" where attackers can establish initial access and maintain presence through automated system processes. The vulnerability essentially transforms routine system operations into potential attack vectors, allowing adversaries to execute malicious code without requiring user interaction or explicit consent.
Mitigation strategies for this vulnerability should focus on immediate system updates to macOS 10.13.4 or later versions where Apple has implemented proper validation of disk image metadata during mounting operations. System administrators should also consider implementing additional security controls such as disabling automatic mounting of external media, configuring disk image verification settings, and monitoring for suspicious disk image mounting activities. Organizations should conduct thorough security assessments of their existing disk image handling processes and ensure that users are educated about the risks associated with mounting unknown or untrusted disk images. The vulnerability highlights the importance of input validation and proper security boundaries in system components that handle user-provided data, emphasizing the need for defense-in-depth approaches that protect against multiple attack vectors. Regular security updates and patch management programs become critical in addressing such vulnerabilities that can be exploited through seemingly innocuous system operations.