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Passwords remain the main means of authentication on the internet. People often forget their passwords and then they have to recover their access to the website services through some kind of mechanism. We try to make that so-called “password recovery” simple and automated, of course. There are several ways to do it, all of them but one are wrong. Let’s see how it is done.
Part 1 – Secret questions
A widespread mechanism is to use so-called “secret questions”. This probably originates with the banks and their telephone service where they ask you several questions to compare your knowledge of personal information with what they have on file. In the times before the internet this was a fair mechanism since coming up with all the personal information was a tough task that often required physically going there and rummaging through the garbage cans to find out things. Still, some determined attackers would do precisely that – dumpster diving – and could gain access to the bank accounts even in those times.
Right now this mechanism is, of course, total fallacy. The internet possesses so much information about you … It is hard to imagine that questions about your private life would remain a mystery to an attacker for long. Your birthday, your dog, your school and schoolmates, your spouse and your doctor – they are all there. It is hard to come up with a generic question that would be suitable to everyone and at the same time would not have the answer printed on your favorite social network page.
And even if it is not. Imagine that the secret question is “what’s your dog’s name?” How many dog names are there? Not as many as letter combinations in a password. And the most common dog names are probably only a handful. So it is by far much easier to brute force a security question than a password.
This mechanism of secret questions and answers is antiquated and should not be used.
There is a variation where you have to provide your own question and your own answer. This is not better. Most people will anyway tend to pick up the obvious questions. The attacker will see the question and can dig for information. The answer will usually be that one word that is easy to brute force. So, no good.
And, by the way, what should you do when you are presented with this folly on a website you use? Provide a strong password instead of the answer. Store that password in whichever way you store all the other recovery passwords. All other rules for password management apply.
So much for secret questions. In the next part, we will see how to do password recovery with a secondary channel.