CVE-2020-3835 in macOS
Summary
by MITRE
A validation issue existed in the handling of symlinks. This issue was addressed with improved validation of symlinks. This issue is fixed in macOS Catalina 10.15.3. A malicious application may be able to access restricted files.
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Analysis
by VulDB Data Team • 04/06/2024
The vulnerability described in CVE-2020-3835 represents a critical security flaw in macOS Catalina 10.15.3 that stems from inadequate validation of symbolic links within the operating system's file handling mechanisms. This issue falls under the broader category of path traversal vulnerabilities and specifically relates to how the system processes symbolic link references, creating potential pathways for unauthorized access to restricted system files and directories.
The technical flaw manifests when the operating system fails to properly validate symbolic link targets during file operations, allowing malicious applications to exploit this weakness by creating or manipulating symbolic links that point to sensitive system locations. This validation gap enables attackers to bypass normal access controls and potentially read or modify files that should be protected from unauthorized access. The vulnerability is particularly concerning because it operates at a fundamental level of file system operations, where symbolic links are commonly used for legitimate system functions but can be abused for privilege escalation or information disclosure attacks.
The operational impact of CVE-2020-3835 extends beyond simple file access violations, as it represents a potential vector for more sophisticated attacks that could compromise system integrity and confidentiality. Attackers could leverage this vulnerability to access sensitive system files, configuration data, or user information that should remain protected by the operating system's security model. The vulnerability's exploitation potential is heightened because symbolic links are frequently used in legitimate system operations, making the malicious behavior harder to detect through standard monitoring mechanisms. This issue directly impacts the principle of least privilege and could enable attackers to escalate their privileges or gain unauthorized access to restricted resources.
Security professionals should implement comprehensive monitoring for suspicious symbolic link creation or manipulation activities, particularly in system directories and user home folders where such attacks might occur. The fix provided in macOS Catalina 10.15.3 addresses the core validation issue by implementing stricter checks on symbolic link targets and ensuring that all symbolic link operations are properly validated against the system's access control policies. Organizations should prioritize immediate deployment of this update and conduct thorough security assessments to identify any potential exploitation attempts that may have occurred prior to the patch deployment. This vulnerability aligns with attack patterns documented in the attack tree methodology where path traversal and privilege escalation are common initial access vectors. The remediation approach follows industry best practices for mitigating symbolic link vulnerabilities and demonstrates the importance of proper input validation in preventing unauthorized system access.