A recent breach at Humble Bundle, marketer of discount computer games, exposes some interesting subtleties about what “data breach” should mean. You can get full details at the link below.
In this case, an attacker entered Humble Bundle’s system but was not able to carry off information wholesale. They did, however, exploit a flaw in Humble Bundle’s code that allowed them to answer a number of yes-or-no questions about Humble Bundle’s customers. The attackers essentially worked their way down a list of emails extracting information for each on whether that email was attached to an active subscription.
This provides a good illustration of a general principle: the more information the bad guys have, the more they can get. Absent other information, the hacker’s exploit of Humble Bundle is pretty useless… given a good guess at all the emails that might have a Humble Bundle subscription, the hacker’s exploit is as good as making off with the full list.
Every little bit of information that can be kept out of the hands of criminals is meaningful.