Android Verified Boot 2.0 and its limitations

There are users who prefer older versions of Android to newer ones, such as Android Pie. And they also like to experiment by returning older versions, even though they are deprived of newer security patches. However, Google decided to put an end to this.

Phones that come pre-installed with Android 9 and later must have integrated Android Verified Boot 2.0. AVB 2.0 is also integrated in some phones pre-nstalled with Android 8, but OEMs have not yet been required to implement it in the Oreo version.

Android Verified Boot 2.0 prevents the phone from starting with an older rollback image, ie if the device is downgraded to an earlier version of the software that is considered vulnerable. In other words, a user with a phone running Android 8.1 and integrated AVB will not be able to reinstall 8.0.

On Meizu smartphones, the AVB 2.0 feature is implemented with Android 9. That is, users with an Flyme interface based on Android 8 and older can safely return older versions of Flyme if the current one does not suit them. They can also easily replace the global with Chinese firmware and vice versa. But owners of Meizu phones with Android 9-based Flyme (first of which is Meizu Note 9), can’t do that. And although the Android version is the same, the key here is the security patch date. For example, if you have switched to the Chinese firmware, you can return to the global one only when a global version comes out with a newer security patch than the current version in your phone.

Also due to Google’s phone security requirements the global Flyme 7 has removed the built-in root, which is considered to make the phone vulnerable. It is still available for the Chinese firmware, but for most models it is necessary to require approval from Meizu, stating the reasons for rooting.

Despite Google’s good intentions, this is likely to reflect on those wishing to become beta testers. If the beta you installed to test is causing problems on your phone for some reason, you can’t downgrade in any way, but you should hope that the next beta or stable version will be out soon.