CVE-2001-0409 in VIM
Summary
by MITRE
vim (aka gvim) allows local users to modify files being edited by other users via a symlink attack on the backup and swap files, when the victim is editing the file in a world writable directory.
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Analysis
by VulDB Data Team • 11/12/2024
The vulnerability identified as CVE-2001-0409 represents a significant security flaw in the vim text editor implementation that affects local users who are able to manipulate backup and swap files through symbolic link attacks. This issue specifically manifests when a victim user is editing a file located within a world-writable directory, creating a scenario where malicious local users can exploit the editor's file handling mechanisms to gain unauthorized access to or modification of files being edited by others. The vulnerability stems from the editor's failure to properly validate file ownership and permissions when creating backup and swap files, particularly in directories where any user can write files. The flaw allows attackers to create symbolic links that point to sensitive files, which the vim editor then overwrites or modifies during normal editing operations, effectively enabling privilege escalation and unauthorized file access.
This vulnerability is categorized under CWE-59 as a "Improper Link Resolution" issue, specifically involving the improper handling of symbolic links in file operations. The technical execution involves a race condition where the malicious user creates a symbolic link with the same name as a backup or swap file that vim would normally create, placing this link in the world-writable directory where the victim is editing a file. When vim creates its backup or swap file, it follows the symbolic link and writes data to the target file instead of creating the intended backup file. This attack vector is particularly dangerous because it operates at the local privilege level, allowing users with minimal system access to compromise file integrity and potentially access sensitive data. The vulnerability is classified as a local privilege escalation issue under the ATT&CK framework as it enables an attacker to modify files that they would normally not have access to, effectively bypassing normal file permission controls.
The operational impact of CVE-2001-0409 extends beyond simple file modification capabilities, as it can lead to complete compromise of file integrity and confidentiality within shared environments. When users edit files in world-writable directories such as temporary directories or shared workspaces, the vulnerability becomes particularly exploitable. Attackers can use this technique to modify critical system files, configuration files, or sensitive user data without requiring elevated privileges. The vulnerability is especially concerning in multi-user environments where shared directories are common, such as development servers, shared workstations, or networked systems where multiple users have access to the same file systems. The damage potential includes data corruption, unauthorized access to sensitive information, and potential system compromise through modification of critical configuration files or binaries. The attack requires minimal technical expertise and can be executed automatically through simple shell scripting, making it a particularly dangerous vulnerability in environments where proper directory permissions are not enforced.
Mitigation strategies for CVE-2001-0409 focus on both immediate operational fixes and long-term security hardening measures. The most effective immediate solution involves ensuring that vim is not run in world-writable directories, as this directly eliminates the attack vector. System administrators should enforce proper directory permissions and avoid creating world-writable directories where sensitive file operations occur. The vim editor itself can be configured to disable backup and swap file creation, or to create these files with more restrictive permissions. Additionally, implementing proper file system permissions and access controls can prevent attackers from creating symbolic links in directories where they should not have write access. Regular system auditing should monitor for world-writable directories and ensure that proper security policies are enforced. The vulnerability highlights the importance of proper file system security practices and the need for editors and applications to properly validate file operations before executing them, particularly in shared or multi-user environments where security controls are essential for maintaining system integrity and protecting sensitive data from unauthorized access or modification.