CVE-2022-3153: Vim NULL Pointer Dereference Vulnerability

CVE-2022-3153 Overview

CVE-2022-3153 is a NULL Pointer Dereference vulnerability discovered in the Vim text editor prior to version 9.0.0404. This memory corruption flaw occurs when invalid arguments are passed to the assert_fails() function, leading to a crash condition. The vulnerability can be triggered locally when a user opens a specially crafted file or executes malicious Vim script code.

Critical Impact

Exploitation of this vulnerability can cause Vim to crash, resulting in denial of service and potential loss of unsaved work. While the vulnerability requires local access and user interaction, it poses a significant risk in environments where Vim is used for automated scripting or where untrusted files may be opened.

Affected Products

• Vim versions prior to 9.0.0404
• Linux distributions shipping vulnerable Vim packages
• macOS and Windows systems with affected Vim installations

Discovery Timeline

• 2022-09-08 - CVE-2022-3153 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-3153

Vulnerability Analysis

This vulnerability stems from improper pointer handling in Vim's internal function processing. When the assert_fails() function receives invalid or unexpected arguments, the code path fails to properly validate the pointer state before dereferencing it. This results in a NULL pointer dereference, causing the application to crash immediately.

The vulnerability requires local access to trigger, meaning an attacker must either have the ability to execute Vim commands on the target system or convince a user to open a malicious file. The attack does not require elevated privileges but does require user interaction to initiate the crash condition.

Root Cause

The root cause is a missing NULL pointer check in the code path handling the assert_fails() function arguments. When malformed or invalid arguments are provided, the function attempts to dereference a pointer that has not been properly initialized or has been set to NULL, triggering a segmentation fault and crashing the application.

Attack Vector

The attack requires local access and user interaction to exploit. An attacker could craft a malicious Vim script file (.vim) or embed malicious code in a modeline within an otherwise benign-looking file. When a victim opens this file in Vim, the invalid assert_fails() call is triggered, causing the application to crash.

The following patch was applied to address the vulnerability:

 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    404,
 /**/
     403,
 /**/

Source: GitHub Vim Commit Change

This patch introduces version 9.0.0404, which includes the fix for the NULL pointer dereference in the assert_fails() function handling.

Detection Methods for CVE-2022-3153

Indicators of Compromise

• Unexpected Vim process crashes or segmentation faults in system logs
• Presence of suspicious .vim files or files with unusual modeline configurations
• Core dump files generated by Vim crashes containing NULL pointer references

Detection Strategies

• Monitor system logs for Vim segmentation faults or crash events using journalctl or syslog
• Implement file integrity monitoring on Vim configuration directories (~/.vim/, /etc/vim/)
• Use endpoint detection solutions to identify anomalous Vim process terminations

Monitoring Recommendations

• Enable core dump collection to analyze crash patterns for potential exploitation attempts
• Configure audit rules to monitor execution of Vim with suspicious file arguments
• Review Vim plugin installations for unauthorized or malicious scripts

How to Mitigate CVE-2022-3153

Immediate Actions Required

• Upgrade Vim to version 9.0.0404 or later immediately
• Avoid opening untrusted files in Vim until the patch is applied
• Disable modeline processing by adding set nomodeline to your Vim configuration
• Review and audit any Vim scripts or plugins from untrusted sources

Patch Information

The vulnerability has been addressed in Vim version 9.0.0404. The fix is available through the official GitHub Vim Commit. Linux distributions have released security updates through their respective package managers. Gentoo users should refer to GLSA 202305-16 for distribution-specific guidance.

Workarounds

• Add set nomodeline to your ~/.vimrc or /etc/vim/vimrc to prevent automatic execution of embedded commands
• Use vim -u NONE to launch Vim without loading any configuration files when opening untrusted content
• Consider using alternative text editors for viewing untrusted files until patches are applied

# Configuration example - Disable modelines in Vim
echo "set nomodeline" >> ~/.vimrc

# Verify Vim version after patching
vim --version | head -1

# Launch Vim safely with no configuration
vim -u NONE suspicious_file.txt