This is a universal fix for SafetyNet on devices with hardware attestation and unlocked bootloaders or custom verified boot keys. It defeats both hardware attestation and the new SafetyNet CTS profile updates released on January 12, 2021. The only requirement is that you can pass basic attestation, which requires a valid combination of device and model names, build fingerprints, and security patch levels.
Passing basic attestation is out-of-scope for this module; this module is meant to defy hardware attestation, as well as reported "basic" attestation that actually uses hardware under-the-hood. Use MagiskHide Props Config to spoof your CTS profile if you have trouble passing basic attestation. This is a common situation on old devices and custom ROMs.
No device-specific features (such as the new Pixel-exclusive Google Assistant design or screen-off voice match) will be lost with this fix.
MagiskHide is required if the device is rooted.
Android versions 8–12 Beta 2 are supported. Heavy OEM skins are not officially supported, but they may work depending on your luck and the particular ROM in question. Please do not report problems on such ROMs.
In order to enforce SafetyNet security, Google Play Services is now using hardware attestation for CTS profile validation in all cases, even when basic attestation is selected. The SafetyNet API response from GMS will report that basic attestation was used, but under the hood, hardware attestation is always used regardless of the reported state. This results in SafetyNet failing to pass due to TrustZone reporting an unlocked bootloader (and a partially invalidated root of trust) in the key attestation result.
We can still take advantage of the fact that this usage of hardware attestation is opportunistic — that is, it falls back to basic attestation if key attestation fails to run — and prevent GMS from using key attestation at the framework level. This causes it to gracefully fall back to basic attestation and pass SafetyNet with an unlocked bootloader.
Key attestation is still available for other apps, as there are valid uses for it that do not involve SafetyNet.
The "not implemented" error code from Keymaster is used to simulate the most realistic failure condition to evade detection, i.e. an old device that lacks support for key attestation.
Ideally, this workaround should be incorporated in ROMs instead of overriding part of the ROM in a Magisk module.
There are 2 options for:
- Blocking GMS in the framework, which is more portable across Android versions and typically less intrusive for ROMs to integrate
- Blocking GMS in the native keystore service, which is slightly more future-proof but may require forking another repository
You only need one of the workarounds on the ROM side. Adding both is redundant.
Commits for the framework version of the workaround:
Commits for the native version of the workaround that modifies the C++ keystore service in system/security:
All of the above commits are also available in the form of patch files in this repository.
The keystore executables and libraries in this repository were built with the commits linked above. The target CPU was changed to generic ARMv8-A for all target devices.
- Android 12 Beta 2: Built from AOSP master for
aosp_arm64 - Android 11: Built from ProtonAOSP 11.3.1 (android-11.0.0_r24) for
redfin - Android 10: Built from LineageOS 17.1 (android-10.0.0_r41) for
taimen - Android 9: Built from AOSP android-9.0.0_r61 for
taimen - Android 8.1: Built from AOSP android-8.1.0_r81 for
taimen - Android 8.0: Built from AOSP android-8.0.0_r51 for
marlin
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