~/bokkapig
hack the box machine writeups

MFA Bypasses

contents

Multi-Factor Authentication (MFA) is a security measure that requires users to provide two or more verification factors to gain access to a system, application, or network. It combines something the user knows (like a password), something they have (like a phone or security token), and/or something they are (biometric verification). This layered approach enhances security by making unauthorized access more difficult, even if a password is compromised. MFA Bypasses are techniques attackers use to circumvent MFA protections. These methods can include exploiting weaknesses in MFA implementations, intercepting authentication tokens, leveraging social engineering to manipulate users or support staff, or exploiting session-based vulnerabilities.

Summary#

2FA Bypasses#

Response Manipulation#

If response is "success":false Change it to "success":true

Status Code Manipulation#

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

2FA Code Leakage in Response#

Check the response of the 2FA Code Triggering Request for leaked code.

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 account 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 the 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 vulnerability

Bypass 2FA by Force Browsing#

If the application redirects to /my-account url upon login while 2FA is disabled, try replacing /2fa/verify with /my-account while 2FA is enabled to bypass verification.

Bypass 2FA with null or 000000#

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

Bypass 2FA with array#

{
    "otp":[
        "1234",
        "1111",
        "1337", // GOOD OTP
        "2222",
        "3333",
        "4444",
        "5555"
    ]
}