SYSTEM code execution via writable service executable

Incorrect permission assignment in Acer Planet9 allows local authenticated users to gain SYSTEM code execution via a writable service executable. The PLANET9DAService background service runs as SYSTEM while an executable it uses grants excessive write access to non-administrative users, so modifying or replacing that file causes attacker-controlled code to run on the next service start or system reboot. Exploitation requires local authenticated access to the host and results in full Windows SYSTEM privileges, with no published indication of remote reachability or required user interaction.