Authentication Bypass in TubeBuddy Chrome Extension

Executive Summary

This vulnerability affects the TubeBuddy for YouTube Chrome extension up to version 5.8.4. It allows an attacker to overwrite authentication tokens by manipulating URL parameters without proper validation. The issue occurs in the TBGlobal.GetToken function where the extension reads unvalidated query parameters t, c, and r from a redirect URL handler. This can corrupt the extension's authentication state and potentially disrupt functionality.

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Detection Guidance

Check for suspicious network traffic involving tubebuddy.com/redirect URLs with parameters t, c, or r. Inspect Chrome extension storage for unexpected token values under keys like tubebuddyToken-<channel ID>. Review browser logs for unauthorized redirects or token modifications.

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Impact Analysis

An attacker could craft a malicious URL that forces the extension to store an attacker-controlled token for your channel. This could disrupt functionality or cause denial of service for your channel. Additionally, the vulnerability enables open redirect attacks, which could be used for phishing by disguising malicious links as legitimate TubeBuddy URLs.

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Mitigation Strategies

Disable or remove the TubeBuddy extension version 5.8.4. Update to the latest version if a patch is available. Avoid clicking untrusted TubeBuddy links. Monitor for unusual authentication errors or channel access issues.

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