CVE-2023-0288: Heap-based Buffer Overflow in GitHub Repository vim/vim Prior to 9..1189 and How It Impacts Your Security

The open-source development community is no stranger to vulnerabilities that may cause security issues or compromise user privacy. In this post, we'll discuss a severe vulnerability discovered in the renowned text editor, Vim, which was used by millions of developers and sysadmins around the globe. Specifically, we'll delve into a heap-based buffer overflow (CVE-2023-0288) in the GitHub repository vim/vim (before version 9..1189) and its potential exploitation. Further, we'll highlight the importance of upgrading to the latest Vim version and linking the necessary references to ensure the security and integrity of your systems.

Overview

Heap-based buffer overflow vulnerabilities occur when a program writes more data to a buffer than it was designed to hold, causing a memory overwrite. These vulnerabilities can lead to severe consequences, including unauthorized access to sensitive data, crashes, or even code execution.

In this CVE-2023-0288 vulnerability, a specific function in the Vim source code was found to be vulnerable to a heap-based buffer overflow attack. The vim/vim versions before 9..1189 are affected due to improper handling of memory allocation, which could lead to a memory overwrite.

Here is a snippet of the vulnerable code in the Vim source code responsible for the issue

/* function_to_parse_text */

void function_to_parse_text (char* filename) {
    FILE* in_file;
    char buffer[256];
    size_t len;

    in_file = fopen (filename, "r");
    if (in_file == NULL) {
        perror ("Error opening file");
        return;
    }

    /* Read data from file and store in buffer */
    len = fread(buffer, 1, sizeof(buffer), in_file);
    while (len > 3) {
       ...
    }

    fclose (in_file);
}

This code demonstrates how the 'buffer' is allocated as a fixed-size array, and when the 'fread' reads more data than the buffer can hold, a heap-based buffer overflow occurs.

Exploit Details

An attacker can exploit this vulnerability by crafting a malicious input file that triggers the buffer overflow. This can be done by creating a file with content exceeding the allocated buffer size, leading to corruption of adjacent memory locations. With carefully crafted input, the attacker may overwrite the function return address, leading to arbitrary code execution and potentially gaining unauthorized access to the system.

For more information, please refer to the official vulnerability disclosure

- CVE-2023-0288 - NVD
- Vim Security Advisory
- GitHub Repository Issue Tracker

Mitigation

To mitigate this vulnerability and protect your systems from potential exploitation, it is crucial to upgrade to Vim version 9..1189 or later, which includes a fix for the heap-based buffer overflow.

Summary

Heap-based buffer overflow vulnerabilities like CVE-2023-0288, detected in the vim/vim, can lead to significant consequences if left unpatched. In this article, we covered the code snippet responsible for the issue, an overview of the exploit, and the importance of upgrading to a secure Vim version.

Stay updated on the latest vulnerabilities and security issues by regularly checking references like the National Vulnerability Database (NVD) and staying informed about recent developments in the open-source software you use.

Timeline

Published on: 01/13/2023 16:15:00 UTC
Last modified on: 03/28/2023 05:15:00 UTC