It's not always as easy as you imply. All the attack vectors you mentioned, require root on the host, before you can make the change or install the trojan.
It's not always as easy as you imply. All the attack vectors you mentioned, require root on the host, before you can make the change or install the trojan.
The attack gives you ability to overwrite any cached page. So you don't need to be root to "edit" /etc/passwd.
Not of the host system, assuming we're talking about a compromised VM, running as a non-root user.