Almost any exchange uses 2-Factor Authentication with One Time Passwords (OTP) and that still isn't good enough against phishing.
That's why on 50x.com we have an optional additional withdrawal OTP with a separate private key to be used only for withdrawals. So, even if you log in via a villain's site with your primary OTP - nobody can withdraw your tokens with it because a separate OTP should be used in this case.
Most people do not realize that KYC is a huge security hole.
If you are able to restore access to your account by providing your ID, passphrase etc., that also means that hackers can do the same. Once they got access to your email account (a protection level is much lower for emails) - they got all your communications, documents, they know all about you - and therefore can provide necessary private data to bypass 2FA on your exchange.
Master Key is a one-time access tool to activate emergency tokens withdrawals from your account to your Emergency Withdrawal Addresses (EWA).
In case the regular authentication method with password and OTP is lost or not working for any reason, Master Key will help you to withdraw your funds and re-open the account with a new password/OTP.
What if someone found out your Master Key somehow? Do not worry!
The worst thing that may happen is an unexpected withdrawal of your tokens to your EWA
Someone got your account details and logged in? Having problems accessing your account? Need to override a security withdrawal delay?
Emergency Withdrawal Address (EWA) is the address in each blockchain for all tokens you have on your account, where your tokens will be sent automatically if you activate Emergency Account Termination. Ideally, your own cold wallet address.
You may say some people can manage to lose all their access details including the Master Key, but even in this case there is a way to recover your tokens.
The bullet-proof recovery option on 50x.com for those who lost all their access keys is an option to withdraw all your tokens to your EWA by entering no more than a login.
You can set your own delay for withdrawal orders and for change requests of your Emergency Withdrawal Addresses (EWA). Received orders will be put on hold for a specified time and executed upon delay expiration. You can increase delay period any time you want, but reducing or canceling the delay will be implemented with the same delay as was set before for withdrawal orders.
You will be able to cancel any withdrawal order on hold during the delay period.