2FA Bypasses

Mindmap

Index	Technique
1	Response Manipulation
2	Status Code Manipulation
3	2FA Code Leakage in Response
4	JS File Analysis
5	2FA Code Reusability
6	Lack of Brute-Force Protection
7	Missing 2FA Code Integrity Validation
8	CSRF on 2FA Disabling
9	Password Reset Disable 2FA
10	Backup Code Abuse
11	Clickjacking on 2FA Disabling Page
12	Enabling 2FA doesn't expire Previously active Sessions
13	Bypass 2FA with null or 000000
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#### Response Manipulation
```
In response if "success":false
Change it to "success":true
```

Status Code Manipulation

If Status Code is 4xx
Try to change it to 200 OK and see if it bypass restrictions

2FA Code Leakage in Response

Check the response of the 2FA Code Triggering Request to see if the code is leaked.

JS File Analysis

Rare but some JS Files may contain info about the 2FA Code, worth giving a shot

2FA Code Reusability

Same code can be reused

Lack of Brute-Force Protection

Possible to brute-force any length 2FA Code

Missing 2FA Code Integrity Validation

Code for any user acc can be used to bypass the 2FA

CSRF on 2FA Disabling

No CSRF Protection on disabling 2FA, also there is no auth confirmation

Password Reset Disable 2FA

2FA gets disabled on password change/email change

Backup Code Abuse

Bypassing 2FA by abusing the Backup code feature
Use the above mentioned techniques to bypass Backup Code to remove/reset 2FA restrictions

Clickjacking on 2FA Disabling Page

Iframing the 2FA Disabling page and social engineering victim to disable the 2FA

Enabling 2FA doesn't expire Previously active Sessions

If the session is already hijacked and there is a session timeout vuln

Bypass 2FA with null or 000000

Enter the code 000000 or null to bypass 2FA protection.

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Articles

• Testing Two-Factor Authentication by NCC Group

Author

Harsh Bothra Vishal Saini