> For the complete documentation index, see [llms.txt](https://ganesha-hk.gitbook.io/cybersecurity-writeups/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ganesha-hk.gitbook.io/cybersecurity-writeups/port-swigger-authentication-labs/lab-7.md).

# lab-7

## 2FA Simple Bypass

**Difficulty:** Apprentice

### Lab Description

This lab's two-factor authentication can be bypassed entirely. You already have valid credentials for the victim's account but do not have access to their 2FA verification code.

**Your credentials:** `wiener:peter`\
**Victim's credentials:** `carlos:montoya`

**Objective:** Access Carlos's account page.

### Solution

**Step 1 — Map the authentication flow**

Log in as `wiener` and complete the full login process, including the 2FA step (retrieve the code from the email client). Observe the endpoint sequence:

| Step                  | Endpoint       |
| --------------------- | -------------- |
| Password verification | `POST /login`  |
| 2FA pin entry         | `POST /login2` |
| Authenticated page    | `/my-account`  |

**Step 2 — Bypass the 2FA step**

Log out and begin logging in as `carlos:montoya`. Intercept the traffic in Burp and forward the `POST /login` request normally — Carlos's password is valid, so this succeeds.

When the browser is redirected to `/login2` (the 2FA pin page), instead of forwarding that request, **drop it** and manually navigate the browser directly to `/my-account`.

The server grants access — Carlos's account page loads without a valid 2FA code ever being submitted.

**Step 3 — Why this works**

The 2FA is poorly implemented on the backend. After a successful password check, the server sets a partially-authenticated session that grants access to `/my-account` regardless of whether the 2FA step was completed. The 2FA page is essentially decorative — the backend never enforces that the pin was actually verified before granting access to protected pages.

### Conclusion

True 2FA requires the server to maintain state confirming *both* factors were successfully verified before granting access. Here the server only checked the password and ignored whether the security pin step was completed, making the second factor trivially skippable.


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