CVE-2020-27896 in macOS
Summary
by MITRE • 12/09/2020
A path handling issue was addressed with improved validation. This issue is fixed in macOS Big Sur 11.0.1. A remote attacker may be able to modify the file system.
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Analysis
by VulDB Data Team • 12/18/2020
The vulnerability identified as CVE-2020-27896 represents a path handling issue that existed within the macOS operating system prior to version 11.0.1. This type of flaw falls under the category of improper input validation, where the system fails to properly sanitize or validate file paths before processing them. The vulnerability allows for potential manipulation of file system operations through maliciously crafted path sequences that could exploit weaknesses in the path resolution mechanism.
The technical nature of this vulnerability stems from inadequate validation of file system paths within the macOS kernel or system libraries responsible for handling file operations. When a path is processed without proper sanitization, an attacker can potentially construct malicious path sequences that bypass normal security checks. This weakness creates opportunities for unauthorized file system modifications, potentially allowing an attacker to access, modify, or delete files that should normally be protected. The issue is particularly concerning because it affects core file system operations that are fundamental to system security and integrity.
Remote attackers can exploit this vulnerability from network-accessible endpoints without requiring local system access or elevated privileges. The impact extends beyond simple file access to potentially enable broader system compromise through file system manipulation. Attackers might leverage this weakness to place malicious code in system directories, modify critical system files, or create backdoors through carefully crafted path operations. The vulnerability represents a privilege escalation vector that could allow attackers to gain unauthorized access to system resources and potentially establish persistent access to affected systems.
The fix implemented in macOS Big Sur 11.0.1 addresses this issue through enhanced path validation mechanisms that properly sanitize and validate all file system paths before processing. This remediation follows established security practices for preventing path traversal attacks and similar file system manipulation vulnerabilities. Organizations should prioritize deployment of the macOS 11.0.1 update to mitigate this risk. System administrators should also implement additional monitoring for suspicious file system activities and ensure that file system access controls remain properly configured. The vulnerability aligns with CWE-22 Path Traversal and represents a typical example of how inadequate input validation can create security weaknesses in operating system components.
This vulnerability demonstrates the critical importance of proper input validation in system-level software components and highlights the potential for seemingly minor flaws to create significant security risks. The remediation approach focuses on strengthening the validation layer that processes file system paths, which is consistent with defensive programming principles and security best practices. Organizations should maintain awareness of similar vulnerabilities in other operating system components and ensure that their patch management processes effectively address these types of security issues. The attack surface for such vulnerabilities remains significant as they can be exploited by attackers with minimal privileges and can potentially provide access to critical system resources.