CVE-2023-29539 - Firefox and Thunderbird Reflected File Download Vulnerability Discovered and Fixed

A new vulnerability has been discovered, affecting multiple versions of Firefox, Focus for Android, Firefox ESR, Firefox for Android, and Thunderbird. The vulnerability, dubbed as CVE-2023-29539, could potentially allow attackers to perform reflected file download attacks and trick unsuspecting users into installing malware.

The issue stems from the improper handling of the filename directive in the Content-Disposition header. If the filename contains a NULL character, it would be truncated, allowing attackers to manipulate the displayed filename and deceive users.

Exploit Details

CVE-2023-29539 primarily affects the way the filename directive is handled. To understand the potential impact of this vulnerability, let's examine the following code snippet:

\x00malware.exe

In this example, the NULL character (\x00) is inserted before the actual filename malware.exe. However, due to the truncation vulnerability, the filename directive will only display the text after the NULL character, causing the user to believe they are downloading a harmless file.

This could potentially lead to a reflected file download attack, where attackers would manipulate web applications to store malicious files with seemingly innocent filenames. Unsuspecting users who download and open these files may inadvertently install malware onto their systems.

Original References

- Official Mozilla Security Advisory
- Vulnerability Details from NVD

Mitigation and Remediation

Users running affected versions of Firefox, Focus for Android, Firefox ESR, Firefox for Android, and Thunderbird should immediately update their software to the latest, patched versions. The software updates are available via the following links:

- Download Firefox
- Download Focus for Android
- Download Firefox ESR
- Download Firefox for Android
- Download Thunderbird

In addition to installing the latest updates, users should exercise caution when downloading files from untrusted sources and pay attention to file extensions. Be especially vigilant when prompted to download files from unfamiliar websites.

Conclusion

The CVE-2023-29539 vulnerability highlights the importance of proper input handling in software applications and the potential security implications of neglecting to address these issues. Users and administrators should ensure that they keep their software up-to-date and remain cautious when dealing with unfamiliar files and websites.

Timeline

Published on: 06/02/2023 17:15:00 UTC
Last modified on: 06/21/2023 15:33:00 UTC