CVE-2021-45884 : Exploit Details and Defense Strategies

Brave Desktop versions 1.17 through 1.33 before 1.33.106 are affected by a vulnerability that leads to information disclosure when specific settings are enabled.

Understanding CVE-2021-45884

What is CVE-2021-45884?

In Brave Desktop versions 1.17 through 1.33 before 1.33.106, enabling CNAME-based adblocking along with a proxying extension using a SOCKS fallback can cause additional DNS requests to bypass the extension, potentially exposing sensitive information.

The Impact of CVE-2021-45884

The vulnerability can result in information disclosure due to DNS requests being issued outside of the intended proxying extension, exploiting the system's DNS settings.

Technical Details of CVE-2021-45884

Vulnerability Description

The issue arises from incomplete fixes related to other CVEs (CVE-2021-21323 and CVE-2021-22916), allowing DNS requests to bypass the proxying extension.

Affected Systems and Versions

Systems running Brave Desktop versions 1.17 through 1.33 before 1.33.106

Exploitation Mechanism

Enabling CNAME-based adblocking and a proxying extension with a SOCKS fallback

Mitigation and Prevention

Immediate Steps to Take

Disable CNAME-based adblocking and proxying extensions with SOCKS fallback in Brave Desktop
Monitor for any unauthorized DNS requests

Long-Term Security Practices

Regularly update Brave Desktop to the latest version
Implement network monitoring measures to detect unusual DNS activities

Patching and Updates

Apply the latest patches and security updates provided by Brave to address the vulnerability.