macOS Big Sur 11.2 beta 2, which was released yesterday, eliminates a feature that allowed Apple apps bypass third-party firewalls, security tools, and VPN apps, according to reports from ZDNet and security researcher Patrick Wardle.
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macOS Big Sur 11 included a ContentFilterExclusionList that let Apple's apps like the App Store, Maps, iCloud, and more to avoid firewall and VPN apps that users had installed. These apps were not able to filter or inspect traffic for some built-in Apple apps.
Security researchers believed that the feature, found last October, was a major security risk as malware could be designed to latch on to a legitimate Apple app and bypass security software. Users who had VPNs installed also risked exposing their real IP address and location to Apple's apps.
Omg we did it! 🤩 Thanks to the community feedback (and ya, bad press) Apple decided to remove the ContentFilterExclusionList (in 11.2 beta 2) Means socket filter firewalls (e.g. LuLu) can now comprehensively monitor/block all OS traffic!! Read more: https://t.co/GJXkRA31e7 https://t.co/BCPqdCjkV0 — patrick wardle (@patrickwardle) January 13, 2021
Apple told ZDNet last year that the list was temporary and the result of a series of bugs related to the deprecation of network kernel extensions in macOS Big Sur. Apple has been addressing those bugs, and in the second beta of macOS Big Sur released yesterday, removed the ContentFilterExclusionList from the macOS code.
When macOS Big Sur 11.2 sees a release, Apple apps will be compatible with VPN apps and will no longer be able to bypass firewalls and other security tools.
Top Rated Comments
<sigh>
Ha ha that cracks me up!
A security researcher example: they want to observe how an app communicates with the network, how its behavior changes when they limit some of that communication, etc. They weren't able to do that with some of Apple's apps. For example, if App Store or Find My had a security bug related to network communication, they would have a hard time finding out. Not only can they not control the traffic from those services, they can't even see it.
A more general-purpose example: you're on cellular (or some other metered connection), and use an app like Trip Mode to limit data usage. Well, you can't see the data some of Apple's stuff uses. App Store or Software Update download a large update in the background? Trip Mode won't be able to tell you.
There were probably some reasons Apple did all this in the first place (for example, one might argue that macOS needs to be able to download updates to Xprotect malware definitions no matter what), but there's also a fair bit of hubris involved. It feels like once they did decide to make that exemption list, all kinds of software teams internally signed up to be added, and that's just opening the floodgates for trouble.
Anyway, all this, it appears, is now resolved.
What an unfortunate “bug” this mustve been for Apple before it was found ;)