content: It's not quite that simple, sudo install whatever only installs packages form your repositories.  Don't add untrusted repositories and everything will (probably) be fine.   I could see however, a soon to come rash of .deb files that are targeted at ubuntu users, just like malicious .exe files.   And of course, people will figure out how to exploit things like the steam platform, or chrome and firefox to execute root level commands via some vulnerability.  Being open source, this is less likely than say windows, but not impossible.       An 'idiot proof' version of linux is Android, where it is an arduous and difficult task to gain root access. However, due to its popularity and the cavalier nature of the average user, exploits and malware are abundant despite that you are essentially running a guest account. The google play store is mostly adware, spyware, malware, and garbage.    No system is invulnerable.