I feel like this topic just keeps going around and around. Every time I'm in a room where someone needs to log into a computer that's not theirs, there seems to be a thing of "Oh, I know their password…", which makes me cringe.
I've written about this before, and even for a previous T-SQL Tuesday, about two years ago, but there's something that I want to stress, which is potentially a different slant on the problem.
A password is not just YOUR secret. It's also a secret belonging to the bank / website / program that the password is for.
Let me transport you in your mind, back to primary school. You had a club. You had a password that meant that you knew who was in the club and who wasn't (something I've seen in movies – I don't remember actually being in one). At some point you had a single password that was used by everyone, but then you found that other people knew the password and could gain entry, because you only needed someone to be untrusted for the password to get out.
You felt upset because that password wasn't theirs to share. It was the property of you, the club owner. Someone got access to your club when you hadn't actually granted them access.
Now suppose I'm an online retailer (I'm not, but there are systems that I administer). You've got a password to use my site, and I do all the right things to protect that password – one-way hashing before it even reaches the database, never even being able to see it let alone emailing it, and a ton of different mechanisms that make sure that your stuff is safe. You've decided to a password which you've generated as a 'strong password', and that's great. Maybe you can remember it, which doesn't necessarily make it insecure. I don't even care if you've written it down somewhere, so long as you're treating it as a secret.
Because please understand, it's MY secret too.
If the password you use gets out, because maybe someone gets into your LastPass account, or maybe someone steals the PostIt you've written it on, or maybe you use that same password at a different site which then gets hacked…
…then that other person has access to MY site as you.
If that other person buys stuff from me as you, I might need to refund you for the money / credit / points you didn't mean to spend. And if I've already sent the goods out, then that's going to hurt me.
If that other person does malicious things on my site because they're accessing it as a privileged user, then that's going to hurt me.
Someone knowing the secret that I've worked hard to keep secret… that's going to hurt me.
I have no control over the password that you choose to use. But please understand that it's not just YOUR password. Use something that is a secret between you and me. I will never know your password, but I want you to make sure that no one else ever does either. Don't reuse passwords.