DroidGuard: A Deep Dive into SafetyNet
summary
DroidGuard implements a 256-register VM that runs a unique bytecode downloaded per attestation (updated roughly every two weeks) to check for root, Magisk, emulators and even Pegasus indicators; values are MBA‑encoded and the native layer is obfuscated (MDA, qbdl, msint). Hardware attestation uses the device key/certificate chain to report bootloader state from TrustZone. Reverse engineering required about five weeks plus two for tooling, produced code‑lifting utilities, and enabled a working bypass of the basicIntegrity flag.
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chapters (22)
- 0:00Introduction
- 1:05Why SafetyNet developed
- 3:59SafetyNet history bypasses
- 5:03Integrity and CTS flags
- 6:28Magisk developer joins Google
- 7:30SafetyNet request flow
- 9:39DroidGuard obfuscation role
- 10:22DroidGuard process updates
- 11:28DroidGuard VM architecture
- 13:59Reverse engineering DroidGuard VM
- 17:13Debugging root detection
- 18:20Root detection checks
- 20:10Pegasus detection telemetry
- 21:58Hardware attestation chain
- 22:40DroidGuard data summary
- 23:22DroidGuard beyond SafetyNet
- 24:05Reverse engineering challenges
- 26:14SafetyNet design limits
- 27:39Magisk bypass reasons
- 28:00Bytecode easter eggs
- 28:46Hardware attestation work
- 29:29Conclusion Q&A
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