2FA Bypass Techniques Repository

This repository contains various methods and techniques for bypassing Two-Factor Authentication (2FA) across different systems. It is intended for educational purposes and security research only, aiming to highlight potential vulnerabilities in 2FA implementations and raise awareness about the importance of security in authentication systems.

Table of Contents

1. Bypass Techniques
2. Misconfiguration Exploits
3. Advanced Bypass Techniques
4. Comprehensive Checklist

Bypass Techniques

1. Flawed Two-Factor Verification Logic

• Summary: Flawed logic allows attackers to manipulate cookies or session variables after the first authentication step to access another user's account.
• Example: Manipulating the account cookie to impersonate a victim after the first login step.

2. Clickjacking on 2FA Disable Feature

• Summary: Using iframes and social engineering to trick the victim into disabling their own 2FA settings.
• Key Steps:
  • Iframe the 2FA disable page.
  • Exploit user interaction through social engineering.

3. Response Manipulation

• Summary: Modifying server response values to trick the system into accepting an unsuccessful 2FA attempt.
• Example: Change success: false to success: true in the response payload.

4. Status Code Manipulation

• Summary: Changing the HTTP status code to bypass security checks.
• Example: Modify a 4xx error code to 200 OK to bypass 2FA.

5. 2FA Code Reusability

• Summary: Reusing old 2FA codes to bypass checks.
• Key Steps: Test code reusability over multiple sessions and across longer durations.

6. CSRF on 2FA Disable Feature

• Summary: Exploiting Cross-Site Request Forgery to disable 2FA without user interaction.
• Example: Use existing session information to disable 2FA through CSRF attacks.

7. Backup Code Abuse

• Summary: Using brute-force and response manipulation techniques to bypass backup code checks.

Misconfiguration Exploits

8. Lack of Brute-Force Protection

• Summary: The absence of rate-limiting allows unlimited attempts to brute-force the 2FA code.
• Example: Repeatedly sending 2FA code requests or brute-forcing code input fields.

9. Missing 2FA Code Integrity Validation

• Summary: Using a valid 2FA code from another account to bypass the victim's 2FA.

10. Password Reset/Email Change - 2FA Disable

• Summary: Exploiting password reset or email change functions to bypass or disable 2FA.

11. Re-sending Code and Reset Limit

• Summary: Resetting the brute-force limit by resending the same code repeatedly.

12. Leaked Token

• Summary: Identifying tokens that are inadvertently leaked in the response or logs.

13. Infinite OTP Regeneration

• Summary: Generating OTPs indefinitely until one matches the required code.

14. Subdomain Vulnerabilities

• Summary: Using outdated or vulnerable subdomains to bypass modern 2FA systems.

Advanced Bypass Techniques

15. Session Permission Attack

• Summary: Exploiting session vulnerabilities to pass 2FA checks on a victim's account using attacker session data.

16. Guessable Cookie Exploitation

• Summary: Exploiting weak cookie structures used in "remember me" features to bypass 2FA.

17. IP Address Manipulation

• Summary: Impersonating a user's IP address using headers like X-Forwarded-For.

Comprehensive Checklist

Main Test Cases

• Test email activation link for automatic 2FA bypass.
• Check if password reset functionality bypasses 2FA.
• Attempt response manipulation (e.g., changing parameter values).
• Try deleting or nullifying 2FA parameters in multi-step authentication.
• Access features without completing 2FA after initial login.
• Test API endpoints for user information retrieval without 2FA.
• Attempt user information updates without completing 2FA.

Advanced Techniques

• Exploit caching mechanisms related to cookie policies.
• Change request methods to bypass 2FA (e.g., GET to POST).
• Manipulate referrer headers to bypass 2FA checks.
• Test for missing 2FA code integrity validation.
• Attempt to use reset password endpoints to bypass 2FA.

OTP Brute Force Scenarios

• Time-based limited environment: Distribute OTP attempts across multiple instances.
• IP-based restrictions: Utilize IP rotation services (e.g., AWS).
• Rate-limited environment: Test case-sensitive variations in email addresses.

Additional Test Cases

• Test for race conditions in login requests.
• Check for session fixation vulnerabilities.
• Analyze the OTP generation algorithm for predictability.
• Verify 2FA enforcement across all API endpoints.
• Investigate potential 2FA bypass in mobile app versions.

Miscellaneous Checks

• Test backup code feature for potential abuse.
• Check for clickjacking vulnerabilities on 2FA disabling page.
• Verify if enabling 2FA expires previously active sessions.
• Attempt to bypass 2FA with null or 000000 as OTP.
• Test browser extensions' impact on 2FA functionality.

Miscellaneous Checks (Continued)

• Test for Session Sharing: Investigate if sharing the session cookies from an already authenticated user bypasses 2FA for another user on a different device.
• Analyze Third-Party Integrations: If 2FA is implemented through third-party services (e.g., Authy, Google Authenticator), verify the security of integrations.
• Verify Logout Behavior: Ensure logging out invalidates all active sessions, including those that bypassed 2FA.
• Inspect Audit Logs: Check if failed or successful 2FA attempts are logged accurately to identify exploitation attempts.

Tools and Techniques

Tools for Exploiting 2FA Weaknesses

1. Burp Suite: Used for intercepting and manipulating HTTP requests and responses.
2. OWASP ZAP: Useful for automated scanning of misconfigured 2FA systems.
3. AuthMatrix: Assists in testing authentication and authorization mechanisms, including 2FA.
4. Hydra/Medusa: Used for brute-forcing OTPs and login credentials.
5. Custom Scripts: Develop Python scripts using libraries like requests for automating specific bypass techniques.

Real-World Case Studies

Case Study 1: CSRF Vulnerability in 2FA Disabling

• Scenario: A financial website allowed disabling 2FA without verifying the current password or requiring additional security measures.
• Outcome: Exploited through a crafted CSRF attack to disable 2FA for victim accounts.

Case Study 2: Infinite OTP Generation

• Scenario: A mobile app allowed unlimited OTP regeneration, and the OTPs followed a predictable pattern.
• Outcome: Exploited by generating OTPs until the correct one was identified.

Case Study 3: Backup Code Leakage

• Scenario: Backup codes were visible in plaintext after a failed login attempt.
• Outcome: Attackers used leaked codes to bypass 2FA for multiple accounts.

Preventative Measures

Recommended Best Practices

1. Rate Limiting: Implement strict rate limits for OTP verification attempts.
2. Session Management: Invalidate sessions immediately after changes in 2FA settings.
3. Logging and Monitoring: Maintain comprehensive logs for all 2FA-related actions and monitor for anomalies.
4. Backup Code Management: Enforce strong, non-guessable backup codes with a single-use policy.
5. CSRF Protection: Apply anti-CSRF tokens to all sensitive actions, including enabling/disabling 2FA.
6. Regular Security Audits: Perform routine assessments to identify and patch vulnerabilities.

Advanced Security Techniques

• Hardened Authentication Flow: Use device binding or biometric-based 2FA for added security.
• Push-Based Authentication: Replace OTPs with push notifications that require user confirmation.
• IP Whitelisting: Restrict access based on trusted IP ranges, combined with 2FA.
• Token Expiry: Set short expiration times for generated tokens.

Disclaimer

This document is for educational and security research purposes only. Any misuse of the techniques described here for unauthorized access or malicious activities is strictly prohibited and may be illegal.

Please use this knowledge responsibly to improve security practices and help protect systems from potential 2FA bypass exploits.

Author: Maylo