Here's an example of security FAIL at its finest.
I have an account for a service online, for which I have to manage things for the rest of my family as well. This service recently switched to another company, and I logged into the new website to find that their policy is that my oldest child is considered an "adult dependent," and I have to get permission to manage the service for her. This "permission" comes in the form of an "invitation" that she needs to send me, which sends me a magic code that I have to input from my account, and then my access is enabled, and everything is supposed to be hunky-dory.
The only thing is, my child is not set up with her own account, because up until now she was just set up as a dependent. So I asked Customer Service what to do, and they said, "Have her register an account and then send you an invitation."
To hell with that. I registered her account myself, which was linked to my own member ID anyway. I figured they would bounce a registration with a duplicate email address, so I used a second email address of my own. They didn't even send a confirmation link to that address; as soon as I registered with all the demographic information (which of course I know quite well), I was logged in to "her" account. And I just took care of business.
So here's where the security design fails, bigtime. I don't know whether someone bothered checking for a duplicate email address on registration, but it didn't matter, because they didn't even use it to confirm before finishing the account setup. And there is absolutely nothing to stop me, as a parent, from setting up the account myself. I can have more than one email address. I know all the demographic info. I can set up the challenge questions with answers that I know. So what is the freaking point of this whole "dependent" exercise?
The fact of the matter is, they have nothing in place to stop an impersonator. Short of reviewing the email address and guessing that it's not hers, there is no way to enforce this ridiculous policy. Drop a cookie to make sure the registering browser is unique? I can delete it. Same IP address? Of course; we live in the same house and she's using my computer. Send her some other individual magic ID number to the house? I get her mail.
This is one of these "paper tiger" security policies that simply annoys me for a span of 15 minutes.