Brute-Force Bypass in phpMyFAQ Two-Factor Authentication

Executive Summary

This vulnerability is a brute-force attack in phpMyFAQ versions before 4.1.7 affecting the two-factor authentication (2FA) mechanism. The failure counter for TOTP code attempts is session-scoped and resets when a user re-authenticates with a correct password or starts a new session. Attackers with a valid password can exploit this by repeatedly resetting the session or re-authenticating to clear the counter, allowing unlimited guesses of the 6-digit TOTP code.

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Detection Guidance

Monitor failed 2FA attempts in phpMyFAQ logs for repeated sessions with correct passwords but failed TOTP codes. Check for unusual session cookie generation rates or multiple new sessions from the same IP during 2FA attempts.

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Impact Analysis

If you use phpMyFAQ versions before 4.1.7 with 2FA enabled, an attacker who knows your password could bypass the 2FA protection. They could repeatedly guess the TOTP code by resetting sessions, potentially gaining full access to your account. This could lead to unauthorized data access, modification, or theft depending on your phpMyFAQ permissions.

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Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. GDPR requires adequate protection of personal data, while HIPAA mandates secure access controls for protected health information. Exploitation of this flaw may result in non-compliance, potential data breaches, and associated legal penalties.

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Mitigation Strategies

Upgrade phpMyFAQ to version 4.1.7 or later. Implement persistent rate-limiting tied to user accounts and IP addresses. Disable session reset on password re-authentication. Enforce one-time use of TOTP codes.

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