CVE-2023-5535 highlights a Use After Free (UAF) vulnerability that existed in the GitHub repository vim/vim before v9..201. This post will examine the vulnerability in detail, share a code snippet to demonstrate the exploit, and provide links to original references that discuss the issue at length.

Background

Vim is a powerful and versatile text editor widely used by developers and system administrators. This vulnerability was identified in the vim/vim repository, belonging to a popular open-source version of Vim, before the release of version 9..201.

Vulnerability Details

The UAF vulnerability occurs when the application releases a memory location without properly updating other parts of the code that reference the freed section. This issue can lead to unexpected results and application crashes.

An example code snippet to show the exploit

// Snippet: Use After Free Vulnerability Example
int *ptr = (int *)malloc(sizeof(int));
*ptr = 42;

free(ptr);  // Memory deallocation

// ... time passes ...

printf("%d\n", *ptr);  // Use after free (UB): ptr still points to the freed memory.

Original References

The following links contain the in-depth details of the CVE-2023-5535 vulnerability, including patches that resolve the issue:

1. Vim GitHub Repository Commit - This commit fixed the vulnerability in the main repository of vim/vim.
2. Vim Security Advisory - This resource provides details on various security vulnerabilities and their corresponding patches related to Vim.
3. National Vulnerability Database - The official entry of CVE-2023-5535 in the National Vulnerability Database (NIST).

A successful exploitation of the UAF vulnerability can lead to several potential impacts, such as

1. Application crashes or abnormal behavior due to the undefined state introduced when using freed memory locations.
2. Information disclosure, as an attacker might utilize freed memory to access sensitive data previously stored in that memory location.
3. Remote code execution (RCE) by exploiting the use of freed memory, which could allow an attacker to execute malicious code remotely on the affected system.

Mitigation

The vulnerability was fixed in Vim v9..201 by correcting the code responsible for memory management and ensuring that there were no instances of UAF. Users are advised to upgrade to Vim v9..201 or newer to protect against this vulnerability. Additionally, developers should be cautious about the proper usage of memory locations and avoid Use After Free vulnerabilities in their code.

Conclusion

The CVE-2023-5535 vulnerability highlights the importance of proper memory management in applications. It serves as a reminder for developers to be constantly vigilant against potential security risks and ensure code adheres to best practices to minimize vulnerabilities. By understanding the use and implications of Use After Free issues, we can build more secure and robust software applications.

Timeline

Published on: 10/11/2023 20:15:00 UTC
Last modified on: 11/03/2023 22:15:00 UTC