CVE-2017-13851 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13 is affected. The issue involves the "DesktopServices" component. It allows local users to bypass intended access restrictions on home folder files.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 01/20/2020
The vulnerability identified as CVE-2017-13851 represents a significant security flaw within Apple's macOS operating system affecting versions prior to 10.13. This issue resides within the DesktopServices component which is responsible for managing various desktop-related functionalities including file indexing and metadata processing. The flaw allows local attackers to circumvent the intended access controls that normally restrict unauthorized access to files within user home directories, creating a persistent security risk that undermines the fundamental security model of the operating system.
The technical nature of this vulnerability stems from improper access control mechanisms within the DesktopServices framework. When the system processes files in user home directories for desktop services such as file indexing or metadata generation, the component fails to properly validate access permissions and user privileges. This weakness creates a path for local users to access files that should normally be restricted based on user permissions, effectively bypassing the operating system's discretionary access control mechanisms. The vulnerability specifically impacts the way the system handles file access during desktop service operations, where insufficient validation allows unauthorized access to home folder contents.
The operational impact of this vulnerability extends beyond simple unauthorized file access, creating potential risks for data confidentiality and system integrity. Local users who exploit this flaw can access sensitive personal files, documents, and potentially system configuration data that should remain protected within user home directories. This represents a direct violation of the principle of least privilege and can enable attackers to gather intelligence about system users, access personal information, or potentially escalate their privileges through further exploitation. The vulnerability is particularly concerning because it affects the core desktop services functionality that runs continuously, providing persistent access to the exploited system.
This vulnerability aligns with CWE-284 which describes improper access control issues, and specifically relates to the broader category of privilege escalation and access control bypass flaws. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and persistence through access to restricted system resources. The flaw demonstrates how seemingly benign system services can become attack vectors when access controls are improperly implemented. Organizations and users should consider this vulnerability in the context of broader security hygiene practices, as it represents a fundamental breakdown in the operating system's security boundaries. The recommended mitigation strategy involves upgrading to macOS 10.13 or later versions where Apple has implemented proper access control measures within the DesktopServices component to prevent unauthorized file access.
The persistence of this vulnerability across multiple system components highlights the importance of comprehensive security testing and validation of system services. DesktopServices is a critical component that runs with elevated privileges and interacts with user files regularly, making it an attractive target for exploitation. The flaw demonstrates how access control mechanisms must be rigorously validated across all system services, particularly those that process user data and interact with file systems. This vulnerability underscores the necessity of regular security updates and patch management programs to address such access control bypass issues that can compromise user privacy and system security.