📌 Lab Name

Authentication — 2FA Simple Bypass

🧠 Introduction

Two-Factor Authentication (2FA) is designed to add an extra layer of security by requiring users to verify their identity using something they know (password) and something they have (OTP, email code, etc.).

In this lab, the application implements 2FA, but it contains a logical flaw that allows attackers to bypass the second authentication step entirely. This write-up explains how the vulnerability was identified and exploited.

🔍 Understanding the Vulnerability

In a properly implemented 2FA system:

  • User must enter valid credentials
  • Then must verify identity using a second factor (OTP / code)
  • Access is granted only after successful verification

In this lab:

  • The application verifies login credentials
  • But fails to correctly enforce the 2FA verification step
  • The user can directly access authenticated pages without completing 2FA

This results in a 2FA bypass vulnerability.

🧪 Step-by-Step Exploitation

Step 1: Log in with Valid Credentials

First, I logged in using the provided username and password.

After login, the application redirected me to a 2FA verification page asking for a security code.

Step 2: Analyze the Application Flow

Instead of submitting the 2FA code, I manually navigated to a protected endpoint such as:

/myaccount or /account

Step 3: Bypass the 2FA Mechanism

Now we can go to login page again with the provided Credentail to solve this lab

First we on the burp suite proxy' Intercept and capture the request for login

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After the new request of the 2FA will appear . So we will simply delete or drop that request from the burp suite proxy and go to the broswer .

after drop the request we go to address bar and we can see like this

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Now we change the location to /login2 -> /myaccount . and we redirect to the account page.

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after write this in the address we will redirect to the my account page .

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This is how we can solve this lab and this how we can bypass the 2FA in web application .

🧠 Final Thoughts

This lab highlights how even well-known security mechanisms like 2FA can fail if implemented incorrectly. Understanding authentication logic is essential for any aspiring penetration tester.

Happy Hacking < 3 .