CVE-2023-39742: Exploring a Segmentation Fault in giflib v5.2.1's getarg.c Component

giflib is a widely used library for handling GIF images. It's open-source and notably utilized by multiple software, browsers, and operating systems to display and manipulate GIFs. However, a vulnerability has been identified in giflib v5.2.1 that can potentially lead to a segmentation fault due to an issue in its getarg.c component.

In this write-up, we will dive into the details of this segmentation fault, including its exploitability and possible impact. We will also refer to the original references and provide a code snippet illustrating the vulnerability.

Vulnerability Details

The vulnerability was found in giflib v5.2.1's getarg.c component. This issue occurs due to improper handling of input in the GifError() function, which can lead to a segmentation fault.

The vulnerability has been assigned the identifier CVE-2023-39742. The official description of this issue in the National Vulnerability Database (NVD) is:

"giflib v5.2.1 was discovered to contain a segmentation fault via the component getarg.c."

A code snippet illustrating the problem can be found below

#include <stdio.h>
#include "getarg.h"

void GifError(const char *fmt,...) {
    va_list args;

    fprintf(stderr, "\nGif-lib error: ");
    va_start(args, fmt);
    vfprintf(stderr, fmt, args);
    fprintf(stderr, "\n");
    va_end(args);

    exit(-3);
}

In the GifError() function, the input string "fmt" and variable arguments are not properly validated, which can lead to the segmentation fault.

Exploit Details

To exploit this vulnerability, an attacker needs to craft a malicious GIF image file with specific content that can trigger the segmentation fault in giflib v5.2.1 when it parses the file. By doing so, the attacker may be able to crash the software or system using the library, potentially leading to denial of service in certain scenarios.

It's significantly more challenging to convert this segmentation fault into remote code execution. However, it's theoretically possible that, with enough effort and specific conditions, an attacker could exploit this vulnerability for more harmful purposes.

Original References and Links

1. NVD - National Vulnerability Database: CVE-2023-39742
2. GitHub Issue: giflib v5.2.1 segmentation fault in getarg.c
3. giflib Official Repository: giflib repository

Conclusion

CVE-2023-39742 is a vulnerability found in giflib v5.2.1's getarg.c component that can cause a segmentation fault due to improper input handling. While it may not immediately pose a severe threat, it's worth keeping an eye on updates and patches for giflib to mitigate any potential risks. Developers and users are also encouraged to use the latest version of giflib to minimize the possibility of exploiting this vulnerability.

Timeline

Published on: 08/25/2023 14:15:00 UTC
Last modified on: 08/28/2023 13:59:00 UTC