Sometime in 2014, I received a database dump from a high profile industry site. I received the file from an anonymous file sharing site via a Twitter user that quickly disappeared. The database contained user names, mail addresses, password hashes (SHA1), the salt used, IP address used to access the site and the approximate geographical location (IP geolocation lookup – nothing nefarious).
I had canceled my subscription in January 2014, and the breach happened later than that. I don’t believe I received a notification of a breach of the database. Many others did, but I absolutely would remember if I had received one – in part because I discussed the breach with a former employee at the blog, and in part, because I was in possession of said DB.
A user reached out to me, seemingly puzzled as to why I would be annoyed by not receiving a notification – seeing as I was no longer a member, why would I care that my credentials were leaked. No-one would be able to log into the site using my account anyways.
Here’s the issue I have with that. I happen to have different passwords for different things – but a lot of people do not. A lot of people use the same password for many different things. Case in point, say you find a user with the email address email@example.com, and someone uses a rainbow attack and finds the password, do you think there’s a likelihood that the same password would work if they try to log into the mail account at Gmail? Sure, it’s bad to reuse passwords, but do people do it. You bet.
So, when your site is breached, I think you have an obligation to inform everyone affected by the breach – regardless of whether they are current members or not. I would imagine anyone in the security industry would know this.