CVE-2019-12138 in MacDown
Summary
by MITRE
MacDown 0.7.1 allows directory traversal, for execution of arbitrary programs, via a file:/// or ../ substring in a shared note.
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Analysis
by VulDB Data Team • 09/21/2023
The vulnerability identified as CVE-2019-12138 affects MacDown version 0.7.1, a popular markdown editor for macOS systems. This directory traversal flaw represents a critical security weakness that enables attackers to execute arbitrary programs on affected systems. The vulnerability specifically manifests when the application processes shared notes containing file:// or ../ substrings, allowing unauthorized access to the underlying file system. The flaw stems from inadequate input validation and path resolution mechanisms within the application's handling of file references. Attackers can exploit this vulnerability by crafting malicious shared notes that contain directory traversal sequences, which when processed by MacDown, can lead to unintended file system access and arbitrary code execution. This type of vulnerability falls under the CWE-22 category, which encompasses directory traversal attacks, and represents a significant concern for applications that handle user-supplied file paths without proper sanitization. The attack vector is particularly dangerous in environments where users may share notes between different parties, as a malicious user could embed harmful path sequences in shared content that would be executed when other users open the note. When exploited, this vulnerability can allow attackers to access sensitive files, execute arbitrary commands, and potentially escalate privileges within the application's execution context. The impact extends beyond simple file access, as the ability to execute arbitrary programs opens doors to more sophisticated attacks including privilege escalation, data exfiltration, and system compromise. The vulnerability demonstrates poor input validation practices and highlights the importance of proper path sanitization in applications that handle file references. From an operational perspective, this flaw could affect any user who shares or receives notes containing malicious path sequences, making it particularly dangerous in collaborative environments where note sharing is common. The attack surface is broadened by the fact that MacDown is designed for note sharing and collaboration, making it likely that users would interact with potentially malicious content from other parties. Organizations using MacDown for documentation, collaboration, or note-taking activities face significant risk if this vulnerability remains unpatched, as it provides a straightforward path for attackers to gain unauthorized access to systems. The vulnerability aligns with several ATT&CK techniques including privilege escalation and execution through malicious file content, making it a valuable entry point for attackers seeking to establish persistent access. Security professionals should consider this vulnerability when assessing the security posture of macOS environments where MacDown is in use, particularly in scenarios involving user collaboration or shared document management. The flaw underscores the critical importance of validating all user-supplied input and implementing proper path resolution controls in applications that handle file references. Remediation efforts should focus on updating to a patched version of MacDown, implementing input sanitization measures, and establishing security awareness training for users who handle shared content. Organizations should also consider implementing network-based controls and monitoring for suspicious file access patterns that might indicate exploitation attempts. The vulnerability serves as a reminder of the importance of secure coding practices, particularly in applications that process user-generated content and handle file system operations. Proper implementation of input validation, path normalization, and access controls would prevent exploitation of this vulnerability and protect against similar attacks in other applications. The security community should view this vulnerability as an example of how seemingly simple input handling flaws can lead to significant security implications, especially in collaborative software environments where trust boundaries are blurred.