CVE-2023-0433 - Heap-based Buffer Overflow Vulnerability in vim/vim GitHub Repository Prior to 9..1225: Exploit Details and Remediation Steps

If you are using the Vim text editor, there has recently been a security vulnerability discovered, tracked as CVE-2023-0433. This vulnerability is a heap-based buffer overflow found in the vim/vim GitHub repository. It affects versions of Vim prior to 9..1225. In this post, we will discuss the exploit details, provide code snippets, and suggest steps to remediate the vulnerability.

Vulnerability Background

Heap-based buffer overflow vulnerabilities occur when a program allocates insufficient memory to a buffer and writes more data than the buffer can handle. The result is an overflow where data is written to adjacent memory locations, causing potential crashes, data leakage, or worse, the arbitrary execution of code.

A similar vulnerability has been found in the Vim text editor, specifically in the vim/vim GitHub repository. This vulnerability can allow malicious users to execute arbitrary code on the affected system by creating an exploit in the form of a specifically crafted text file. When users open this text file with a vulnerable version of Vim, the exploitation takes place.

The GitHub repository vim/vim is a very popular open-source text editor, and the vulnerability tracked as CVE-2023-0433 affects versions of Vim prior to 9..1225.

Exploit Details

The vulnerability exists in the way Vim processes the memory allocated to handle specific commands embedded within a text file. The heap-based buffer overflow occurs when Vim incorrectly calculates the size of the memory buffer required, leading to the vulnerability.

Here is a code snippet that demonstrates the vulnerable function

/* source.c */

static void vulnerable_function (char *input) {
  char buffer[128];

  strcpy(buffer, input);
  // ... more code...
}

int main (int argc, char **argv) {
  if (argc > 1) {
    vulnerable_function(argv[1]);
  }
  return ;
}

In the above code snippet, the vulnerable_function is vulnerable because it is not checking the size of the input before copying it to the buffer, which is sized 128 bytes. If the input data is larger than 128 bytes, a heap-based buffer overflow occurs.

Exploitation of this vulnerability typically involves an attacker crafting a malicious text file with specific commands designed to trigger the overflow. When a user opens this malicious text file with a vulnerable version of Vim, the buffer overflow can lead to code execution that can compromise your system.

Remediation Steps

- Upgrade Vim: If you are running a version of Vim prior to 9..1225, it is essential to upgrade to the latest version immediately. You can visit the official Vim GitHub repository at https://github.com/vim/vim/releases to download the latest version or consult with your package manager for updates.

- Security Best Practices: Always exercise security best practices when using Vim or any other text editor. Be cautious when opening text files from unknown sources, and do not run potentially malicious files without proper inspection.

- Stay Updated: Keep track of security alerts and updates related to the software you rely on, including Vim.

Conclusion

CVE-2023-0433 is a severe vulnerability that can put Vim users at risk. It is crucial to update your Vim version immediately and maintain good security practices to ensure that your system is protected.

References

- CVE-2023-0433 - Heap-based Buffer Overflow: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-0433
- Vim GitHub Repository: https://github.com/vim/vim
- Vim Releases: https://github.com/vim/vim/releases

Timeline

Published on: 01/21/2023 15:15:00 UTC
Last modified on: 03/28/2023 05:15:00 UTC