Parallels Desktop local privilege escalation via appliance extract argument injection

Parallels Desktop runs prl_disp_service as root. Local clients reach it on the world-writable socket /var/run/prl_disp_service.socket. PrlSrv_LoginLocal accepts peer credentials. No Parallels signature. No admin group.

After login, PrlSrv_InstallAppliance lets you pick the appliance folder (sVmParentPath). The daemon unpacks with one string, tar -xf "%1" -C "%2", then Qt QProcess::splitCommand chops that string into words. A quote in the folder name closes early. The leftover text becomes extra tar flags. macOS tar --use-compress-program= runs the named program as root.