Alex booted the PC into Safe Mode with Networking and ran Sysinternals Autoruns and Process Monitor.
Filtering for *arm32*, they found a scheduled task named UpdateARM32Optimizer that ran an executable hidden inside:
C:\Users\Public\fonts\systemarm32aonly.img.xz
Decompressing the .xz file revealed a small Linux ARM32 root filesystem — designed to run in a Windows Subsystem for Linux (WSL1) or a hidden QEMU instance. The “extra quality” string was embedded in a config file:
extra_quality = 1 # enables GPU passthrough for crypto mining
In file‑sharing and modding communities, “extra quality” often tags: systemarm32aonlyimgxz extra quality
Legitimate firmware updates do not use “extra quality” as a version descriptor.
Android Go, older smartphones, and some IoT devices rely on ARM32. These devices have limited RAM and no 64‑bit support. System images for them are smaller and require careful memory management.
The correct term is .img.xz.
XZ compression reduces OTA package sizes dramatically. For example, a 2 GB system image may compress to under 600 MB.
How to extract .img.xz:
xz -d system.img.xz
After extraction, you can mount or flash the .img file. Alex booted the PC into Safe Mode with
xz -t system-arm32-a-only.img.xz
Step B: Decompression You must extract the image before flashing.
xz -d system-arm32-a-only.img.xz
# Output: system-arm32-a-only.img
Step C: Deployment (Flashing)
This image is flashed to the system partition of an Android device. xz -t system-arm32-a-only.img.xz
Step D: Wiping Data (Critical) Since this is likely a GSI (Generic System Image), a "dirty flash" (installing without wiping) often causes "Extra Quality" issues like crashes or battery drain.