Finding Serious ‘Sign In with Apple’ Hole Earns Security Researcher a $100,000 Bug Bounty

An anonymous reader quotes Forbes: When Apple announced Sign in with Apple at the June 2019 worldwide developers conference, it called it a “more private way to simply and quickly sign into apps and websites.” The idea was, and still is, a good one: replace social logins that can be used to collect personal data with a secure authentication system backed by Apple’s promise not to profile users or their app activity… Unsurprisingly, it has been pushed as being a more privacy-oriented option than using your Facebook or Google account.

Fast forward to April 2020, and a security researcher from Delhi uncovered a critical Sign in with Apple vulnerability that could allow an attacker to potentially take over an account with just an email ID. A critical vulnerability that was deemed important enough that Apple paid him $100,000 through its bug bounty program by way of a reward. With the vulnerability already now patched by Apple on the server-side, Bhavuk Jain published his disclosure of the security shocker on May 30.


It applied “only to third-party apps which used Sign in with Apple without taking any further security measures,” the article points out , adding that the researcher who found it “said Apple carried out an internal investigation and determined that no account compromises or misuse had occurred before the vulnerability was fixed.”

But they also quote an SME application security lead at ImmersiveLabs who said he “would have expected better testing around this from a company such as Apple, especially when it is trying to set itself a reputation as privacy-focused.”