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Zero-day in Sign in with Apple

bhavukjain.com

21–30 of 280 posts

Re: Zero-day in Sign in with Apple

#21
post #17

Wow, I'm so glad that apple forced me to implement this broken garbage into my apps! For those not aware, some time ago apple decided it would be a good idea to develop their own sing in system, and then force all apps on their store (that already support e.g. Google Account login) to implement it. So they brought a huge amount of additional complexity in a large amount of apps, and then they fucked up security. Than…

I still trust Apple over a rando site or SaaS app. No system is flawless.

Re: Zero-day in Sign in with Apple

#22
> The Sign in with Apple works similarly to OAuth 2.0.

> similarly

I understand why they wanted to modify OAuth 2.0, but departing from a spec is a very risky move.

> $100,000

That was a good bounty. Appropriate given scope and impact. But it would have been a lot cheaper to offer a pre-release bounty program. We (Remind) occasionally add unreleased features to our bounty program with some extra incentive to explore (e.g. "Any submissions related to new feature X will automatically be considered High severity for the next two weeks"). Getting some eyeballs on it while we're wrapping up QA means we're better prepared for public launch.

This particular bug is fairly run-of-the-mill for an experienced researcher to find. The vast majority of bug bounty submissions I see are simple "replay requests but change IDs/emails/etc". This absolutely would have been caught in a pre-release bounty program.

Re: Zero-day in Sign in with Apple

#23

> The Sign in with Apple works similarly to OAuth 2.0. > similarly I understand why they wanted to modify OAuth 2.0, but departing from a spec is a very risky move. > $100,000 That was a good bounty. Appropriate given scope and impact. But it would have been a lot cheaper to offer a pre-release bounty program. We (Remind) occasionally add unreleased features to our bounty program with some extra incentive to explore…

Apple supposedly marks certain beta builds with a bounty multiplier. I say supposedly because like their "research iPhones" they mentioned it in a presentation once and I never heard about it again.

Re: Zero-day in Sign in with Apple

#24
post #17

Wow, I'm so glad that apple forced me to implement this broken garbage into my apps! For those not aware, some time ago apple decided it would be a good idea to develop their own sing in system, and then force all apps on their store (that already support e.g. Google Account login) to implement it. So they brought a huge amount of additional complexity in a large amount of apps, and then they fucked up security. Than…

I still trust Apple over a rando site or SaaS app. No system is flawless.

Fortunately some rando site or SaaS app doesn't have the leverage to force me to implement additional garbage! Apple does, and did. I'm still surprised that this didn't trigger an antitrust investigation like when Microsoft abused their monopoly to push internet explorer. This is exactly the same thing, if not worse.

Re: Zero-day in Sign in with Apple

#26
post #24

Earlier quoted context omitted.

I still trust Apple over a rando site or SaaS app. No system is flawless.

Fortunately some rando site or SaaS app doesn't have the leverage to force me to implement additional garbage! Apple does, and did. I'm still surprised that this didn't trigger an antitrust investigation like when Microsoft abused their monopoly to push internet explorer. This is exactly the same thing, if not worse.

[deleted]

Re: Zero-day in Sign in with Apple

#27
post #17

Wow, I'm so glad that apple forced me to implement this broken garbage into my apps! For those not aware, some time ago apple decided it would be a good idea to develop their own sing in system, and then force all apps on their store (that already support e.g. Google Account login) to implement it. So they brought a huge amount of additional complexity in a large amount of apps, and then they fucked up security. Than…

I still trust Apple over a rando site or SaaS app. No system is flawless.

I think I trust Apple over a random website too, but was adding an additional kind of sign in and forcing everyone to use it even needed in the first place?

Re: Zero-day in Sign in with Apple

#29
post #10

> I found I could request JWTs for any Email ID from Apple and when the signature of these tokens was verified using Apple’s public key, they showed as valid. This means an attacker could forge a JWT by linking any Email ID to it and gaining access to the victim’s account. Great writeup there. Looks like a Apple JWT bug and the verification went through despite it being 'signed' and 'tamperproof'. Clearly its footgun…

In the apps I write for my org integrating with the org SSO provider, I treat the JWT tokens mostly like a non-JWT token. Verify the token with the IDP, map the token to a specific user and never relying on the JWT payload user info for the resource auth. It takes additional 0.25s during the login process but has never let me down. As the SSO provider was issuing non-JWT tokens few years back, this was the way we went about making sure the user is who they are saying they are and just stuck with the same approach when they moved to JWT tokens.

Re: Zero-day in Sign in with Apple

#30
Perhaps slightly related that finding Apple zero days was less bounty award than finding Android zero days.

I think we can wrap up the security and anonymous part that Apple has been claiming for their overpriced devices.

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