TOTP Brute Force in Planka Application

Executive Summary

PLANKA versions 2.2.0 to 2.2.1 do not properly restrict repeated attempts to submit incorrect TOTP codes via the POST /api/access-tokens/verify-totp endpoint. This allows attackers to brute force six-digit two-factor authentication codes within a ten-minute window if they already know the user's password. Successful guesses grant access to the user's full account.

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Detection Guidance

Monitor POST requests to /api/access-tokens/verify-totp for repeated failed TOTP attempts within a short timeframe. Check server logs for multiple six-digit code submissions from the same IP or user account.

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Impact Analysis

If you use PLANKA 2.2.0 or 2.2.1 and your password is compromised, attackers can bypass two-factor authentication by repeatedly guessing the TOTP code. This could lead to unauthorized access to your account, data theft, or further exploitation of the system.

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Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles and HIPAA's security requirements. Organizations may face compliance breaches, legal penalties, and reputational damage if user data is exposed due to insufficient authentication controls.

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Mitigation Strategies

Upgrade PLANKA to a version beyond 2.2.1 that fixes the TOTP verification flaw. Implement rate limiting on the /api/access-tokens/verify-totp endpoint to prevent brute force attempts. Consider disabling pending tokens after a single failed attempt.

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