Duplicati v2.3.0.1 backup software gives Authenticated Users MODIFY permissions that propagate to all subdirectories. Installing the software outside of the Program Files directory, or on a custom path, creates a LocalSystem service running from a directory that any standard local user can write to. A standard local user can overwrite any DLL in the service directory. On service restart, the OS loads the attacker's DLL before any managed code runs, executing arbitrary code as SYSTEM.