Analysisfirmware reverse engineeringwearablesjieli ac6958embedded security
Researchers Reveal Smartwatch Firmware Produces False Readings
6.2
In December, reverse engineers published a follow-up blog post detailing extraction and analysis of a 2‑MB firmware image from a JieLi AC6958‑based smartwatch, parsing JLFS headers and decrypting a scrambled FATFSI partition using a recovered root key (0x170f). Their analysis recovered app.bin and other files, exposed an LFSR‑based scrambler, and concluded the device's heart‑rate and blood‑pressure measurements are unreliable.
Key Points
- 1Extracted 2‑MB firmware and parsed JLFS headers to locate app.bin, FATFSI, and other partition files
- 2Decrypted FATFSI by recovering root key 0x170f and documenting the LFSR‑based ENC scrambler algorithm
- 3Advises practitioners to distrust this smartwatch's vital‑sign claims and audit firmware and sensor chains
Scoring Rationale
Detailed, reproducible firmware decryption with practical impact; limited scope to a specific JieLi SoC and single device model.
Sources
Public references used for this report.
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