However, in a mind-boggling turn of events, the app contained a password reset function that was incredibly poorly designed. It allowed anyone to request a password reset for other people's accounts, but have the password reset link sent to their email address, instead of the legitimate account owner. A hacker only needed to know a 7pay user's email address, date of birth, and phone number. An additional field in the password reset section allowed the hacker to request that the password reset link to be sent to a third-party email address (under the hacker's control), with no need to dig through the app's code or tamper with HTTP requests, like most of these hacks involve. Furthermore, if the user didn't enter their date of birth, the app would use a default of January 1, 2019, making some attacks even easier,
according to a report in Yahoo Japan. With so much data about Japanese users lying around the internet from the multitude of past breaches, a hacker only had to compile it and automate an attack.